f: IV "r tj^JD',u;:l' H-'lOtDs- -^ >* ^- Surgeon General's Office iJf/L A. H. Xj , Js/L. ID., ACTUOB OF " A TREATIBK OF INFLAMMATORY DISEASES," ETO. --------------------.■■■ '. i BO S T ON: '«■-•' D K (r I-i X AXD K 8 T K S , No. 2'i CORMIILL. 1864. P) yy nX.y- Eutt-icd, according to Act of Congress, in the year 1863, by E. SMALL, In the Clerk's Ollicu of the District Court of the Di>nict of Massachusetts PREFACE. The origin of this work may be briefly stated. Within the last ten years the author has been requested, at various times, to address assemblies, particularly Sabbath Schools and Lyceums, upon the subject treated on in this book. The thought and study necessary to the preparation of these lecture?, has impressed him with the belief that the numerous works on Anatomy and Physiology, designed for the use of schools and for popular reading, have been essentially deficient, inasmuch as reference is seldom made in them, to the proofs that stand out so prominently in every part and organ of the humaji body, of the wisdom and goodness of God in its formation. This, perhaps, should not be expected in purely scientific works upon these subjects, designed solely for the Student of Medicine; yet, even in these, an occasional reference to the abundant proofs of creative goodness, would not be out of place. But in works designed for popular instruction, such deficiency is certainly a defect. 1V PREFACE. The inhabitants of the forest—the aboriginese of this conti- nent, may pass unnoticed, or gaze with stupid indifference, upon the stately specimens of artistic skill which adorn large cities; and in them it is excusable. But educated and Christian com- munities, with works of science in one hand, and in the other the book of inspiration, which asserts that "our bodies are temples of the Holy Ghost," are certainly without excuse, if, while they admire the works of art, they fail to observe in this livhvj "temple" the exquisite workmanship of the divine Architect, and to trace out the benevolent designs in its struc- ture, the proofs of which are so abundant. Yet, if authors fail to bring these impressive proofs of divine goodness promi- nently before the public eye, it cannot be expected that they will be discovered and appreciated by the young, or by the popular mass. But no such work has ever fallen under the observation, or come to the knowledge of the author; and being impressed with the belief that benefit would accrue to the public, especially to the young, from such a work, morally as well as in a literary sense, has prompted the effort, the result of which is here pre- sented to the public, whether for its approval or condemnation, will be subsequently seen. The author has deemed it proper to present what to him appears incontestable proofs of the existence, and wonderful capacities, of the human soul. He has also attempted to show, what, perhaps, none will deny, and yet what few fully appreciate, PREFACE. y that all things, animate and inanimate, mind and matter, are under the control of established law; that health and vigor of body and mind, depend upon strict obedience to laws which control animate nature; and that all suffering is the result of violated law. The laws of health have been carefully considered, what constitutes their violation pointed out, and directions given for their observance. After due deliberation the author decided to adopt the collo- quial or conversational style, not, however, without being aware of the objections to, as well as the advantages of, such a style. The author has endeavored so to present the subject as to combine pleasure with the acquisition of knowledge, and render study and reading at once agreeable and instructive. In most works of this character, technical terms constitute a serious obstacle to the common reader. In this, their use has been avoided as far as is deemed profitable. Anatomical words have been divided into syllables, and those accented, marked. While this work is not offered as a complete treatise upon the subject, it is believed to embrace all the leading and prominent facts, leaving out only the minute and abstruse, which could be of no benefit to the popular reader or young student, and could interest only the professional man. The author is fully aware that this little work is open to criticism. That it is free from faults he cannot indulge a Vi PREFACE. hope; and all he asks is, that the public will exercise candor, and award to him the credit of an honest intention, and a desire to contribute his mite to the general good, and especially to that of the young. If it shall serve in any degree to excite thought, and give additional interest in the study of Man, physically, mentally and morally, and impress upon the young the conviction of God'a goodness in their formation, and awaken stronger desires for greater knowledge upon this subject, the labor bestowed will not have been in vain. It will be seen that this work is fully illustrated with beau- tiful engravings. These illustrations are taken from a valuable work recently published, entitled « The Household Physician," by Dr. Ira Warren of this city, to whom the author's acknowl- edgements are due. Boston, Mass., Sept., 1863. TO TEACHERS AND PARENTS. The author believes he states a fact from which few will dissent, when he asserts that Anatomy,* Physiology, and Hy- giene, in the manner in which they have been presented to the public, particularly to the young, have been dry and uninter- esting subjects, and to many, absolutely repulsive. But the author has long been satisfied, that it is not the nature of the subject, but the mode of presenting it, which has produced this impression upon the mind. Few subjects can be proposed for the study of the young, or persons of any age, which contain so many facts of thrilling interest, when properly presented, as the sciences I have named. The importance of correct and familiar knowledge relative to the structure of our physical system, the various functions performed by its numerous organs, the laws which control these functions, and the means best adapted to preserve them in a healthy condition, every thoughtful person will admit. Deeply to be regretted, then, is the fact, that a subject of such vast moment to man's best interests, and capable, when rightly pre- sented, of affording pleasure and delight, as well as valuable vii Aiii To TKAiJHKRS AND PARENTS. instruction, should be presented in such a manner as to fail to secure these important ends. The present work, to which your attention is most respect- fully called, is an attempt,—how successful others must judge —to remedy the evils here referred to. The colloquial style, the author is aware, is a novel one in which to present such a subject, but he ventures to hope that it will be interesting to the young, and that the book will be found in some good degree, to fill the desideratum which has so long existed, and has been so deeply felt. An important advantage in the colloquial style is, that to answer the interrogations, renders it proper and necessary to explain in the most familiar manner, and to descend to minute particulars to an extent that could not, with propriety be done in any other style of writing; thus not only allowing, but rendering it necessary to use familiar language and the most natural mode of expression in explaining the numerous topics dwelt upon. The division of technical words into syallables, with the accented ones marked, as has been done in this work, will enable even the ordinary reader to give a correct pronuncia- tion, to acquire which is of great importance. On account of the familiar style, the author has not deemed it necessary to append questions. If, however, it should be found on trial that questions would aid the teacher and parent and facilitate the progress of the pupil, they will be added b future Editions. TESTIMONIALS. A Treatise on Physiology, by E. Small, M. D.—I have .ork with great interest, and think it admirably adapted to the use of schools and families—particularly, with perhaps some abridgement, to the Sunday School Library. It presents a correct system of Anato- my, Physiology and Hygiene, in a style to gain the attention of the young; and in language simple, flowing and easy of comprehension. Every person who reads the work carefully will be struck with the vast number of ways in which it sets forth the Divine Wisdom and Goodness in the structure of the human system. Into the heart of every child, who becomes familiar with its contents, will sink the lesson that he is the workmanship of a Father, who seeks only benevolent ends by wise and benevolent means. IRA WARREN, M. D. Boston, Dec. 7,1863. Bigelow School, Boston, July 7, 1863. I have thoroughly tested a manuscript work on Physiology, by E. Small, M. D., in my class of fifty pupils,—the first class of the Bigelow Grammar School, and I regard it as a work for the young, above praise. It fills a vacuum in that science which every earnest teacher has so often realized. Some of the chapters explore a new field—one which no other author has ventured to enter. Most happily has the author revealed the divinity of the human sys- tem. I know of no work so admirably adapted to teach, not only Phys- iology, but a pure Theology to the young, as this. I long to see it in print, and again avail myself of its able assistance in teaching that in- teresting science. This work is full of " object lessons" for schools, lessons divested of the stiffness and formalities which too often charac- terize school books. Physiology in this work is presented to the mind in an attractive manner, the conversational style, which is peculiarly suited to the tastes of children. Some of my pupils who thought Physiology and Hygiene to be dry studies, have learned by the aid of this manuscript, to love them, and look forward with eagerness to the recitations. TESTIMONIALS. While I regard this work as admirably prepared for a text book in teaching Physiology in schools, it is equally well adapted to instruct and interest families and the common reader. I know of no work for chddren that so beautifully portrays the divine character. In every topic the All-Wise Father is so revealed that the heart of the child spontaneously flows forth in devout gratitude and affection to the Author of his being. R. C. MATHER, Head Assistant in the Bigelow School. [From Rev. L. D. Barrows, D. D.] Nearly all our text-books on Physiology, being prepared for the medi- cal profession or the high schools, are so scholastic and technical that they are altogether above the comprehension of the common masses of our youth. How then shall they become informed on this subject ? It seems an absolute necessity that some work should be prepared for them, divested, as far as possible, of technicalities, and whatever else renders the study of the subject dry. This is the precise demand which the author of this work has most happily supplied. A child with ordinary common school intelligence, at ten or twelve years, will understand every para- graph of it. And being put in the conversational form, renders it still more attractive to the young. Thus it will be found, whether this volume is used as a text-book in the schools, or for family reading, it will not fail to tiike a deep hold of all inquiring minds. Something also must be done to clothe science and useful literature with more attraction, or we can never compete with the intoxicating excitement of romance. This book is a step in the right direction! Another impressive fact is,—the author has made it cardinal in this work to keep God before his readers and pupils, both in his wisdom and good- ness. There is also, a loud call for some treatise on Physiology quite different from anything now before the people, which shall be more practical in character. It is well to know how many bones we have, and how they are put together; but how much more health and happiness depend on our knowledge of the proper care and use of the stomach; and what rekuon diet, exerci,,, clothing bathing, rest, etc., sustain to helltn Th,s, perhaps, 18 one of the crowning excellences of this book. Full and unportantdetadsare found in it of practical instruction for preven ion of disease, suffering and prematura AM+\, tu prevention suggests are worth moiTZfEl co1 \ tfese ™m™ unitary be without it It will wove s, „ w ,?g" amily can afford to Boston, NovemW,^^ CONTENTS. Conversation Page I. INTRODUCTORY...................................... 17 II. THE BONES AND JOINTS ........................... 21 HI. JOINT3 OF THE BODY (Continued).................. 45 IV. THE MUSCLES ......................................- 57 V. THE MUSCLES (Continued)........................... 71 VI. THE NERVOUS SYSTEM:............................. 82 Vn. THE NERVOUS SYSTEM (Continued)................. 98 Vni. DIGESTION AND NUTRITION......................... 108 IX. DIGESTION AND NUTRITION (Continued) .......... 132 X. THE BLOOD-VESSELS AND LUNGS................... 140 XI. THE CIRCULATION OF THE BLOOD................ 155 XII. THE CIRCULATION OF THE BLOOD (Continued) .... 170 Xin. THE SECRETORY ORGANS OR GLANDS............. 187 XIV. ABSORPTION......................................... 199 XV. THE SKIN ......................................... 214 XVI. THE TEETH........................................... 228 XVn. THE SPECIAL SENSES-THE SENSE OF VISION..... 243 XVHI. SENSE OF HEARING................................. 235 XIX. THE SENSE OF SMELL............................... 280 THE SENSE OF TASTE............................... 284 THE SENSE OF TOUCH............................... 291 XX. MISCELLANEOUS .................................... 293 XXI. THE SOUL............................................ 312 XXII. LAW.................................................. 327 XXUI. HYGIENE—THE PRESERVATION OF HEALTH----34G XXIV. HYGIENE............................................3G1 XXV. DIET................................................382 XXVI. HYGIENE............................................ 413 ANATOMY AND PHYSIOLOGY, CONVERSATION I. INTRODUCTORY. The Creator's power demonstrated by his works—His good- ness AS CLEARLY PROVED BY HIS WORKS AS HIS POWER. Father.—My deaf children, I am happy to meet you again in our study, where we have often conversed with so much pleasure, and, I trust, with profit. Frederick.— vYe are all here, Father, waiting with much interest to hear what you will say on the new subject about which you promised to speak at the next meeting. Frank.—I feel sure we shall be delighted. Mary.—I am anxious for you to commence at once. Father.—You must be patient, my children, if you would be profited; to attain which, we must be sys- tematic, and proceed in the order due to such a subject. Fred.—I know, Father, you are always for reducing every thing to system and order. I feel desirous to 17 18 ANATOMY AND PHYSIOLOGY The earth's velocity. know what proof you can give of God's goodness in the formation of our bodies. I should be glad to have proof that God is good, for in our last conversation we were alarmed at what you told us of the power of God, so that I am really afraid to pray. Father.—What did I say, my son, that frightened you? Fred.—You said that this earth on which we live, which is more than twenty-five thousand miles in circumference, is moving in its orbit round the sun at the rate of more than one thousand miles a minute. Fa titer.—That is so, my son; and that you may be able to form a better estimate of such amazing velocity, I will hear state what I then neglected to say, that the speed of the earth in its annual revolution round the sun, is more than one hundred times greater than that of a ball shot from a cannon, which is about six hun- dred miles an hour, or ten miles a minute. In other words, while a cannon ball travels one mile, the earth goes one hundred. Frank.—Is that possible? Father.-lt is not only possible, but it is a fact which may be easily demonstrated. The earth is not only moving at this prodigious rate, but the moon which revolves round it at the distance of two hundred and forty thousand miles, is also carried along with t At the same time the earth revolves on its own ax s from west to east, every twenty-four hours; and aU RENDERED ATTRACTIVE. 19 Creator's power and goodness. these wonderful and complicated movements are so uniform and regular, that not a jar is produced, nor can we realise that the earth moves at all. Frank.—I am startled, Father, at your statements ! Father.—As startling as this appears, it is still a more thrilling fact, that there are countless millions of worlds, some a thousand times larger than our earth, which are flying through infinite space with a surprising degree of velocity, and wTith the utmost exactness and order. It is certainly very proper that we should feel the most profound awe when we contemplate the works of God ; and could we not discover proofs of goodness as well as power in them, we might well fear and tremble. Frank.—That is just what I have been thinking, Father, since our last conversation. For, if such power is not controlled by goodness, how do we know that it will not be exerted for our destruction? It seems to me that it would be cause for terror, rather than love. Mary.—It appears to me just as Frank says. I cannot doubt the power of the Creator—his works prove it. But do his works prove his goodness as clearly as his power? Father.—I think so, my daughter. And by a careful study of his works, especially in the structure of our bodies, we shall see that his goodness is as fully demonstrated as his power. And what can be more 20 ANATOMY AND PHYSIOLOGY.________ God's impress on our body.___________- ennobling than such a study? Or what can inspire a greater degree of devout adoration to the God who made us. At the close of our last interview I promised to commence a series of conversations at our next meeting, in which I was to prove the wisdom and goodness of the Creator by the structure of the human body, which promise I shall now attempt to redeem. And if the display of power impresses us with a feeling of awe, the manifestation of goodness should certainly inspire us with love. Fred.—So it seems to me. And I have sometimes thought, when reading the book of Exodus, that could I have stood with Moses on Mount Sinai and heard God speak,—or could I have seen the tables of stone on which he wrote the ten Commandments, I should ever after have felt the most profound awe and ado- ration. Father.—But, my son, let me assure you that the finger of God has left its impress upon your own body, as clearly traced as were the ten commandments upon the tables of stone ; nor should the adoration be less profound in the one case than the other; for it is the finger of God in both; and where God is seen, or leaves his impress, "let man adore." CONVERSATION II. THE BONES AND JOINTS. Anatomy, Physiology and Hygeine defined—Name and defini- tion OF PARTS OF WHICH THE BODY IS COMPOSED—OSTEOLOGY-- Number, name, and location of the bones—Uses of the bones —Joints of the body—Sinotial fluid, or joint water. Children.—We are again waiting very impatiently, Father, hoping that this time you will tell us something of what you say is so wonderful in the formation of our bodies. Father.—I am pleased, my dear children, to find you so much interested in the subject upon which we are to converse, and I hope you will not be disappointed in the pleasure and profit you anticipate. But I must again check your impatience, before I commence to give the description of our bodies that I have promised. System and "order is Heaven's first lawT," in all His works, and it should certainly be ours in attempting to investigate them. I must here state, at the begin- ing, that I do not intend, in these conversations which I have promised you, to go into the minutias of the Anatomy and Physiology of the human body; yet, to talk intelligibly, we must have some knowledge of these subjects. I am well aware that Anatomy, Phy- 21 22 ANATOMY AND PHYSIOLOGY Organs of the bodyi siology and Hygiene, are usually regarded by young people as dry subjects, and destitute of interest, if not a i >so iutely repulsive. But this is an erroneous view, and is the result of a wrong presentation of the subject to the youthful mind. Of the truth of this statement I hope to convince you, before we close this series of conversations. Of the importance of such knowledge, no thoughtful person can indulge a doubt. In what I intend to say I shall pursue the following course :—I shall first briefly describe the Anatomy and Physiology of each part and organ of the body upon which we speak, as the bones, muscles, nerves, stomach, heart, lungs, eyes, ears, teeth, skin, lymphatics, arteries, veins, capillaries, &c, after which I shall explain the laws which control the health of the various organs and parts of the body. Mary.—I did not suppose, Father, that you were going to talk to us about the bones, the heart, the veins, and such things, for it always frightens me to hear about them. ,1 thought you would tell us some wonderful things about the formation of our bodies, and show us that God is good to make us as we are.' Fred.—So I thought. Father.-So I will; but in order to do so, I must first describe the parts of which our bodies are com- posed. Should you see a machine in operation which indicated great wisdom and skill in the one who in vented and constructed it, the complicated movements RENDERED ATTRACTIVE. 23 What Anatomy and Physiology is. of which you felt desirous to understand, but which you could not comprehend without a careful study of all its parts separately, that you might see the connec- tion and influence each part has with, and upon the other, in producing the results you witnessed, what would you do ? Fred.—I should examine and study the parts sepa- rately, of course. Father.—If, then, to understand a complicated ma- chine, made by man, you would examine the parts separately, how much more necessary is it, in order to comprehend the infinitely more complicated piece of mechanism God has made—our bodies—to study its numerous parts and organs, and their movements, separately ? Fred.—I suppose it must be so, and to this I have no objection. But you said you would describe the anatomy and physiology of the numerous organs of the body. Father.—So I did; and a study or description of the numerous organs of the body I have named, and their functions, is the study of Anatomy and Phy- siology. Frank.—Why, Father, I thought Anatomy and Physiology was something more than that! Father.—No, it is just that. But it would be well, perhaps, to express it in a little more exact and scien- tific manner. 24 ANATOMY AND PHYSIOLOGY Definitions of terms. Anatomy, in its primary meaning, is the art of dissecting, or artificially separating the different parts of an animal body. But the term is more commonly applied to a description of the structure, mechanism and organization of living beings. Physiology is the science of the functions of all the diflerent parts or organs of animals while in a state of health, or the office which they perform in the economy of the individual. Hygiene is the art or science of preserving health, upon which I shall speak at some length in the closing conversations of the series. All bodies or substances are either organic or inor- ganic. Organic bodies have organs, upon whose action their growth depends. Animals and plants are includ- ed in this division. Inorganic bodies are devoid, both of organs and of life. Earths and minerals are of this class. All organized bodies possess a power which we call vitality, by which they are developed from within by a process called nutrition, which consists in converting certain substances to their own nature by the action of then* organs. AH animal bodies derive their origin from parents, or pre-ex.sring bodies of the same kind, and have a period of growth, maturity and deeav, and a limited RENDERED ATTRACTIVE. 25 Parts defined. period of life, wdiich varies with different species, from a day to a century. Animal or organic life is under the control of law, the violation of which shortens the period of life alloted to man ; a fact upon wThich I shall speak more fully in a future conversation. The various parts of the human body are arranged into what are called Fil'-a-ments, Fi'-bres, Tis'-sues, Or'-gans, Ap-pa-ra'-tus-es, and Sys'-tems; which terms I will explain, or define. A Filament is a fine thread of which flesh, nerves, skin, etc., are composed. A Fibre is a slender thread, composed of several filaments united, and enclosed in a sheath. It con- stitutes a part of the form of animals. A Tissue is formed by a particular union, or inter- lacing of fibres. An Organ is an arrangement of tissues forming an instrument designed for action. The action of an organ is called its, function. To illustrate. The lungs are organs of respiration, and breathing is one of their functions. The liver is an organ, and its function is the secretion of bile. An Apparatus is a union of several organs for the production of certain results. Tne digestive apparatus 26 ANATOMY and physiology Name and use of parts. affords a good example. It consists of the teeth, salivary glands, stomach, pancreas, liver, eta, all uniting to aid in the digestion of food. "The term, System, is applied to an assemblage of organs arranged according to some plan, or method; as the nervous system, the respiratory system." Mem'-brane, or Tissue, is a thin, white, flexible skin, formed by fibres interwoven like a net-work. There are several kinds of membrane, as the Mw- cous, Se'-mus, Cell'-u-lor, Ad'-i-pose, Mus'-cu-lar, &c. The Mucous Membrane lines the mouth, nose, stomach, bowels, lungs; in short, all cavities which communicate with the air. The function of the Mucous Membrane, or the small glands situated in its substance, is to secrete a viscid, slippery fluid caUed mucous, the object of which is to lubricate the surface, and thereby prevent chafino- and irritation. The Serous Membrane lines an closed cavities which have no communication with the air, such ps the skull, chest etc. It secretes a watery fluid which lubricates the organs or parts it envelopes. This membrane, when diseased, sometimes secretes too great an amount of water, which constitutes dropsy of the brain, chest, and other organs. RENDERED attractive. 27 Membranes. The Cellular Membrane is a net-work of cells, varying greatly in size and shape. It is composed of small fibres, running in every possible direction, and extending throughout the entire body. These cells communicate with each other, and the fluid they contain flows from cell to cell, and in consequence of disease, often becomes too great, producing general dropsy. The Adipose Membrane, or Tissue, forms distinct bags or cells, which contain a substance called fat. There is, in many instances, a great deposit of this substance in personswho are corpulent. This material, is deposited chiefly around the heart and kidneys, and under the skin and muscles of the abdomen. Persons may become enormously enlarged by an increase of this tissue without any increase in the size of their muscles. " Such a condition," as an interesting writer justly remarks, " is to be deplored; the body having become merely the store-house or depot of myriads of pots of fat." " The Muscular Membane is composed of many filaments, that unite to form fibres, each of which is enclosed in a delicate layer of cellular membrane. Bundles of these fibres constitute a muscle." Muscles are designed for hard labor, as I shall explain at a future time. They have much lifting and pulling to do. They are therefore composed of minute fibres. Mary.__Why are they made of small fibres ? 28 anatomy and physiology Tissues. Father.—That they may have the greatest possible strength in the smallest compass. Fred.—lhive they any greater strength for being composed of small fibres ? Father.—Certainly they have. Popes, you know, are made of small cords or threads, for the reason, that, in no other way can they be made of the same diameter to possess the same strength. The four cables which support the Suspension Bridge at Niagara Falls, are each composed of 3659 small wires, for the reason that no solid iron of the same diameter (10^ inches) could sustain such an immense weight. So the muscles, made up of vast numbers of hair-like fibres, possess a degree of strength truly astonishing, and almost incredible, as I shall show when describing them. The Nervous Tissue consists of two substances. The one, is of a gray color, and of a pulpy character. The other is white, and of a fibrous character. Both these substances are united in every part of the nervous system. "The Fibrous Tissue consists of longitudinal, parallel fibres, which are closely united. These fibres in some situations, form a thin, dense, strong mem- brane, like that which lines the internal surface of the skull, or invests the external surface of the bones In -ther instances, they form strong, inelastic bands rendered attractive. 29 Tissue. called lig'-a-ments, which bind one bone to another. This tissue also forms ten'-dons, (white cords,) by which the muscles are attached to the bones." The Cartilaginous Tissue, or Cartilage, is smooth, firm, and highly elastic. The ends of the bones which come together to form joints, are covered with it. Its color is a pearly white. The Osseous, or Bony Tissue, varies in arrange- ment of matter and density of structure, in different bones, and at different periods of life. The arrange- ment of bony matter is such as to give a cylindrical form to some bones, while others are disposed of in plates, or are flat. Some bones are dense and compact, others porous and spongy. A space in the center of Ions' bones is filled with a substance called mar'-row, the design or use of which has long been a subject of controversy among physiologists. But I fear, my children, that you are beginning to feel disappointed, and have already come to the con- clusion, that after all that has been said, I have intro- duced to your attention only a dry subject, one in which you can never feel any interest. Frank.—I have no such feeling, Father. It is true, I feel desirous to know what there is in the formation of our bodies to prove God's goodness. But I know it is necessary that we should have knowledge of the anatomy and physiology The human skeleton Fig. 1. THE HUMAN SKELETON. .vFiC1- Ll* rePresents the spinal column; 2, the skull; 3. the lower iaw-4 the breast bone (sternum); 6, the ribs: 7, the collar bone; 8, the bones of the H?i>eJiKrin(-h"mer^); ?' the shoulder joint; 10, the radius; 11, the ulna; 12, the elbow joint; 13, the wrist; 14, the hand; 15, the haunch bone- 16 the sacrum; 17, the hip joint; 18. the thigh bone 19. the knee pan (patella)' 20 the knee jomt;21, the fibula: 22, the tiSia; 23, ankle joint; 24^ the foot K 28' 2Mhe ligamente of the shoulder, elbow, and wrist; 3J, tie large arterv o 'the MM^fX'T °f0!,heoKhiLjoi.nt: 82',he large bloid vessel of the* thigh* 83, the artery of the leg: 34, 35,36, ligaments of the knee pan, knee, and anile RENDERED ATTRACTIVE. 31 Osteology. different parts and structures of which our bodies are composed, else we could not understand your expla- nations. Father.—That is true, my son. And I must be- speak your patience a few moments longer while I give a very brief description of the bones of which our bodies are composed, which by Anatomists is called osteoloo-tz-. There are, in the human body, two hundred and forty bones, including the teeth, which are usually reckoned at thirty-two. Fig. 2. THE HEAD. Fi2 2 1,1, the front and upper part of the skull and coronal suture: 2, the sagittal suture on the top of the skull: 3, 3 the lambdoidal sutures running down on each side of the back part of the skull. 32 anatomy and physiology Frank.—Why, Father, your first statement sur- prises me ! Can it be possible that there are two hundred and forty bones in our body? I did not suppose there was a tenth part of that number. I should like to know where they all are. Father.—I will tell you where they are, and will also present to you these fine engravings to illustrate the bones I describe, which I wish you to study care- fully. And that you may the better understand, I will divide them into four parts. 1st. The bones of the head, including the teeth, are sixty-two ; eight in the skull, four in each ear, and fourteen in the face. Fred.—I can see but four bones in the skull. Father.—The skull bones are double; that is, they are formed of two tablets or plates, one underneath the other, with a porous, spongy layer of bone between. These two plates of bone give very great protection to the brain, the outer one being tough and fibrous, and the other very hard. The bones of the skull are united by what are called sut'-ures, which are ragged edges, interlocking each other somewhat in the manner of what by carpenters is styled dove- tailing. These bones are quite open in early life, but in old age the sutures close and the bones are firmly united. The bones of the ears will be described in a future conversation when we come to speak of that oro-an. rendered attractive. 33 Bones of the Trunk. The bones of the Face serve for the attachment of the powerful muscles by which the jaw is moved in masticating food. They also sustain the soft parts of the face in place. 2d. The bones of the Trunk—fifty-four—twenty- four in the Spi'-nal Col'-umn, (back bone) ; twenty- four Ribs, four in the Pel'-vis ; one at the base of the tongue called the Os-hy-oid'-es; and the Ster'-num, (breast bone). These bones are so arranged as to form the two Fig. 3. THE THORAX OR CHES Fi> 3 1 is the spine: 2, 2, the collar bones: 3,3, the seven upper, or true ribs-S4 4 the five lower or false ribs: 5, the breast bone^to which the true ribs'"are united-6 the sword-shaped cartilage which constitutes the lower end of the breast b'or/e called cnsiib.xn cartilage: 7, 7, the upper part of the two hinrrs 8 8 theVi-ht lung, seen between the ribs: 9, 9, ihe left lung: 10,10, the heart:' U il, tie 8 faphragm, or midriff; 12 12, the liver; 18.18, fte stomach; 14 14 the second stomach, or duodenum; 15, the transverse colon; 16, the upper part I,f the colon on the right side; 17, upper part of colon on left side. 34 ANATOMY AND PHYSIOLOGY Bones of the Trunk._____________________ great cavities of the body: the Tho'-rax (chest) and the Ab-do'-men. The Thorax is formed by twelve bones of the spinal column posteriorly, or on the back part, the sternum in front, and the ribs at the sides. The sternum in ehildhood consists of eight pieces of bone, which in adults are so united as to form but three. The seven upper Bibs, called the true ribs, are united in front to the sternum, and in the rear to the spinal column. The next three, called false ribs, are united to the spine, and in front are united to each other by eartilage. The other two are connected only with the spine, and are called floating ribs. The SrixAL Column is composed of twenty-four bones, each of which is called a ver'-te-bra. Each bone has seven projections called pro'cess-es, to four of which, muscles are attached for the purpose of bind- ing the bones together, while the other three serve as attachments for the muscles of the back. The vertebra are so arranged that a tube is formed, in the spinal column, in which the spinal cord is placed. The Pelvis. The four bones which form the pelvis are the two in-nom-i-na'-ta (nameless bones), the sa'-crum, and the coc'-cyx. In childhood, the innomi- nata consists of three bones, which in adults are united and become one. In these bones is a deep cup-like RENDERED ATTRACTIVE. 35 The Pelvis. depression, or socket, called the ac-e-tab'-u-lum, in which the head of the thigh-bone is placed to form the hip joint. Fig. 4. THE PELVIS. Fig. 4. 1,1, the innominata: 2, the sacrum: 3, the coccyx: 4, 4, the acetabu- lum : a, a, the pubic portion of the nameless bones: d, the arch of the pubis: e, the union of the sacrum and the lower end of the spinal column. The Sacrum. Between the right and left innomi- nata is a wedge-shaped bone called the sacrum, to which the two innominata are firmly bound by liga- ments. The sacrum forms the base of the spinal column, to which it is attached by the lower vertebra. The Coccyx is the lower extremity of the spinal column. In infancy it consists of several small bones, which, in youth unite and become one. 3d. The bones of the upper extremities—sixty-four. These are the Clav'-i-cle, (collar bone) ; the Scap'-u- la, (shoulder blade) ; the Hu'-mer-us, (first bone of 36 ANATOMY AND PHYSIOLOGY Bones of the upper extremities. the arm) ; the Rad'-i-us and W'-na, (bones of the fore-arm) ; Car'-pus, (wrist) ; Met-a-car'^pus, (the hand) ; and the Pha-lan'-ges, (fingers and thumbs). The Clavicle is attached at one end to the scapula, Fi-. r>. Fist 7. THE HUMERUS.-THE ULNA & RADIUS. J^t\ha\\il thfsh£ft of ,the bo°?:u2, the large round head which fits into the glenoid cavity ; 3. the surface which unites with the ulna. . Fi? 6. 1, is the body of the ulna; 2, the shaft of the radius; 4, the articulat- Yr'u,'fa" w 'th which the lower eiid of the humerus unites; 6, the upper ex- «Ma«tM,br^Sb f0,m8 tbC elbow^ 6. *• Po-t where ffeufna 1V 7. 1 he eight bones of the wrist or carpus, are arranged in two rows aii.l I emg hound close together, do not admit of very freemot on S L C 1 , boi.es of the Inst row, 1', T, M. U. the second row of the carpal bones'll 11 r e .l.u metecarpal bones of the hand; 2, 2, the first ranee of filler boneV'i k fcf'^=S.^f b0M" * 4>tbe tb^ «"«• of fingSho^eftife RENDERED ATTRACTIVE. 37 Bones of the upper extremities. and at the other to the sternum. Its use is to keep the arms in their proper place. The Scapula is a thin, flat bone, of a triangular form. It is located upon the upper and back part of the chest, and is kept in its position by muscles, by the contraction of which, it is moved in various di- rections. The Humerus is the largest bone of the arm. Its form is cylindrical. The upper extremity is attached to the scapula by the glenoid cavity or socket, forming the shoulder joint. At the other extremity it is con- nected at the elbow with the ulna of the fore-arm. The fore-arm is the part between the wrist and the elbow. The Ulna is connected with the humorus and forms the elbow joint. It is situated on the inner side of the arm. The Radius is joined to the bones of the carpus and forms the wrist-joint. It is placed on the outside of the fore-arm. These two bones of the fore-arm,—the ulna and ra- dius, at their lower extremities, articulate with, or are joined to each other, by which means the hand is allowed to rotate. The Carpus is composed of eight bones bound firmly together by strong bands or ligaments. 38 ANATOMY AND PHYSIOLOGY Bones of the lower extremities. The jNIetacarpus consists of five bones. Upon four of them the first bones of the fingers are placed, and the first bone of the thumb upon the other. Fig. 8. Fig. 9. THE FEMUR OR THIGH-BONE. THE TIBIA AND FIBULA r- a , • fc B0NES OF THE LEG ir^ter'Mn^^h^^; &r,i 6' * a p]°Jection "ailed the of the femur which fitsnto th£acetabulumt I T attached : 3 the union of the niotor and sensitive roots. After the union, the nerve, wMi its motor and sensitive filaments, divides and subdivides as it passes on, and is distributed to the tissues of the several organs. color, and is contained in the cavity of the cranium or skull. It is divided into two parts, one called Cer'-e-bimm, • the other Cer-e-bel'-lum, or the great and little brain ; the cerebrum being about seven times greater than the cerebellum. The cerebrum occupies all that portion of the skull which lies above the level of the ears, and is the seat of intellect. The cerebellum, or little brain, occupies the lower and back part of the head, and is separated from the cerebrum by a membrane. It is supposed to be the seat of the animal propensities. RENDERED ATTRACTIVE. 87 Cranial nerves. Fig. 22. THE BRAIN. Fig. 22. The skull bones and membranes being removed. The scalp turned down is represented by A, A; E, E, E, show the cut edge of the bones; C, ia the dura mata, drawn up with a hook; F, the convolutions of the brain. There is also the Me-dul'-la Ob-lon-ga-ta, Avhich is the top of the spinal cord. It is regarded as a portion of the brain, being enclosed within the skull. It is made up of three pairs of bodies, being so united as to form a bulb. The brain is invested or covered Avith a firm mem- brane called Du'-ra Ma'-ta, and also with the Pi'-a Ma'-ta, which is a broad net of blood-vessels that ex- tend through the different parts of the brain to supply it Avith blood. Enveloping the brain, and reflected upon the inner surface of the dura mata, is a serous membrane called the A-rach'-noid. 88 ANATOMY AND PHYSIOLOGY Spinal cord and nerves. The brain is divided into right and left hemispheres, and each hemisphere into three lobes. All the surface of the two hemispheres is divided into convolutions, varying in size, and more or less projecting, each of which is siq)posed to be the seat of some faculty or quality of the mind, (See Fig. 22, page 87). The convolutions are separated from each other by winding furrows, into which the pia mata descends, while the arachnoid coat, and the dura mata envelope the whole brain. The spinal cord is contained in the cavity of the spinal canal. It consists of both sensitive and motive filaments, distinct in the cord, but united after leaving it, forming mixed nerves, which 1 shall soon explain. The nerves which proceed from the spinal cord, supply the muscles of at least nine-tenths of the Avhole body, and are distributed upon the neck, trunk and extremities. They are called the motor and sensitive nerves, or the nerves of motion and sensation. The cranial nerves, which proceed directly from the brain, are distributed mostly upon the head and upper part of the body ; as the optic nerves to the eye, giving vision or sight; the auditory nerves to the ears, giving hearing; the olfactory nerves to the nose, giving the sense of smelling; the gustatory nerves to the mouth, giving the sense of taste. Fred.—O, Father, I now understand what you mean by seeing, hearing, tasting and smelling with RENDERED ATTRACTIVE. 89 the nerves. You mean that the eyes, ears, etc., are supplied Avith nerves Avhich give them the poAver of seeing and hearing. Father.—That is correct, and I Avill explain it more fully in future conversations. The nerves are white cords. They divide and sub- divide into branches so minute as to be invisible to the naked eye, and form a network over the whole "body, so perfect that the point of the finest needle cannot be introduced under the skin, Avithout touching and Avounding one or more. They form a medium of communication between one organ and another, and connect all organs and parts of the body Avith the brain, which may be regarded as the origin and center of the nervous system. Frank.—You say, Father, that the spinal nerves are nerves of motion and sensation. Are not the nerves which extend from the brain to the eye, ear, nose and mouth, capable also of feeling or motion? Fattier.—No ; these nerves can perform no function but the special one for which they were designed ; the optic nerves, that of seeing, the auditory nerves hearing, the olfactory nerves smelling, and the gustatory nerves tasting. Should these nerves be touched with the point of a needle, or irritated in any other Avay, it would cause no pain nor any convulsive motion, as it does in the motive and sensitive nerves. But the effect of the irritation and injury of these nerves, would 90 ANATOMY AND PHYSIOLOGY Nerves in pairs'. be to injure or destroy the function of the organ for which they are specially designed—the eyes, ears, etc. Three pairs of the cranial nerves, hoAvcver, are capable of sensation, and of some degree of motion. The fifth pair is capable of very intense pain. It is the sensitive nerve of the face, and is the seat of that painful disease called neuralgia, or tic douloureux. Frank.—I think, Father, Ave understand your ex- planation of the action of the nerves Avhich proceed * from the brain, and I feel very thankful to you for it; but I do not quite understand about the spinal nerves, which you say are nerves of motion and sensation. I wish you would explain to us how these nerves pro- duce motion and feeling. Father.—I will do so, my son, with pleasure. You recollect I told you that the nerves were in pairs— that is, a pair consists of tAvo distinct nerves, and each nerve of a pair is totally different in its action or function, from the other nerve of the same pair; one being a sensitive nerve, whoso function is to pro- duce feeling, the other a motive nerve whose function is to produce motion. The sensitive nerve conveys to the brain and mind, any impression made upon that part of the body upon which the nerve is dis- tributed ; and the motive nerve conveys from the brain to the surface or extremities of the body, the intention of the mind; the action of one being from the surface and extremities of the body inward to the brain, the RENDERED ATTRACTIVE. 91 _______Action of the nerves._______________The nerves a telegraph! other outward from the brain to the surface and ex- tremities. To illustrate. If I place my hand upon a hot iron, the effect,—the sensation of pain—is con- veyed from the hand to the brain and mind, by the sensitive nerve ; and the intention of the mind is con- veyed from the brain to the hand by the motive nerve. In this case, the sensitive nerve conveys to the brain and mind, the intelligence that something is injuring or destroying the hand. This information is conveyed to the mind, that it may decide what shall be done to save the hand from threatened destruction; and the mind sends back the order to the muscles, through the motive nerve, to remove the hand from the iron. The muscles instantly obey the command, and thus the hand is saved. The action of these nerves is with the speed of light- ning. If you have any doubts about it, I will tell you hoAv you can remove them, and also prove the truth of what I here state. Just touch a finger to a hot iron, and see how long a time Avill be required to con- vey the fact to the brain, and receive back an order to remove it. And yet, all I have here stated of the action of the nerves, must take place, before the finger can be removed from its painful contact with the iron. This is the first, and most perfect telegraph line ever established; one set of wires (nerves) to convey intelligence from the surface and extremities to the 92 ANATOMY AND PHYSIOLOGY Action of the nerves. brain; and another set to carry back the order or in- tention of the mind, to the surface and extremities. In this Avay, the condition and Avants of every part and organ of the body are made known to the mind. The sensation in the stomach, Avhich Ave call hunger, which is simply a demand of the system for nutriment, is transmitted to the mind through the sensitive nerves, and the mind sends back to the stomach, through the motive nerves, the order to take food, and obedience to the order at once removes the sen- sation of hunger. I step upon a pointed nail Avhich pierces the foot, and the fact is instantly transmitted, or telegraphed to the brain, and the brain, as quick as thought, sends back a dispatch, ordering the mus- cles Avhat to do. An interesting fact which I must not fail to mention in this connection, is the following:—The sensitive nerves not only convey to the mind the fact that a part of the system is in danger of being injured or destroyed, but it conveys also the particular nature of the injury; or, in other words, the sensation or pain produced by the injury, informs the mind what the injury is. Otherwise, the mind could not act intelligibly in re- turning an order to the part, what to do to avert the threatened injury. Fred.—Hoav can that be, Father? Father.—You know, my son, that different sensa- tions are produced by different causes. If you should RENDERED ATTRACTIVE. 93 Cause of different sensations. :---- ----»— place the hare foot upon a hot iron, or live coal, the sensation would be very different from that produced by stepping on ice, or into the suoav. In like manner, different diseases, and different locations of disease, produce very different sensations, and thus suggest the proper remedy. The headache is a very different pain from that produced by gout or rheumatism, and that caused by neuralgia is totally unlike that pro- duced by fever. If painful sensations from Avhatever cause were the same, when the causes producing them are so various, how could the mind be informed of the true cause? and if not informed of the cause, how could it direct to the remedy ? Fred.—O, Father ! I feel deeply interested in the information you are giving us in regard to the action of the nerves. It is new to me, although I have read something about them. But there is one thing I Avish you would explain to us—not that I doubt the truth of it, but I wish to know Avhat proof there is. I refer to the statement you made, that one nerve of each pair is a sensitive nerve, and conveys impressions to the brain ; and the other a motive nerve, conveying back the intention of the mind. Now I Avish to knoAv how that fact can be proved ? Father.—Your queries are very proper, and I intended to explain the interesting fact, and give the proof, if you had not asked it. In explaining this, I must first state, that nervous 94 ANATOMY AND PHYSIOLOGY Nervous fluid—its existence proved. action is produced by the transmission through the nerve, of what is called the nervous fluid, or nervous force, Avhich some suppose to be identical with, or to strongly resemble the electric fluid. What the exact nature of the nervous fluid is, has not yet been fully decided; but one thing is certain, to prevent or in- terrupt its circulation, utterly destroys the tiction of the nerves, both of the sensitive and motive. For example :—If a ligature or thread be tied around the sensitive nerve that is distributed upon the hand, so as to cut off the communication betAvccn it and the brain, the sensation of the hand would thereby be entirely destroyed. In that condition, if the hand should be burned off, no sensation or pain would bo produced. If the motive nerve should be tied, all power of motion would cease. In that case, if the hand should be placed in fire, one Avould writhe Aviththe pain, but could no more remove the hand than they could re- move a mountain. These facts have been proved in numerous instances by experiments on animals. Mary.— This is Avonderful, Father. I am interested and surprised at what you have told us about the nerves. Father.—My daughter, I have many facts yet to state, iu regard to them, not less interesting and im- pressive than those I have been describing. I have stated that the spinal nerves Avere in pairs, RENDERED ATTRACTIVE. 95 Union of motive and sensitive nerves. each pair consisting of a sensitive and a motive nerve. These nerves arc separate as they leave the spine ; one, the motor, proceeding from the anterior or front, and the other, the sensitive, from the posterior or back side of the spinal column, (See Fig. 21, page 86) ; but they soon unite, and the nervous fibres or filaments of each nerve commingle so as to form, apparently, but one nerve. Frank.—Well, Father, if they unite and form one nerve, I suppose that nerve can be neither a sensitive nor a motive nerve ; and \>vay, Avhat is it? Fred.—I think you will find it difficult to answer Frank's question; for I recollect you said that the spinal nerves were the sensitive and motive, and now you say they unite and form one, and that the fibres of each mingle and commingle together. I thought it very fine, Avhen you had tAvo distinct sets of nerves, but uoav you have mingled them all together, and, it seems to me, have just spoiled the Avhole, and I do not see AAdiat you arc going to do with them. I suppose, however, you will find some Avay to explain, and bring it all right. Father.—In tracing out and explaining the Avorks of the Creator, avc shall never become perplexed, if our explanations and deductions arc truthful. In the fact I have stated, and which you seem to think so perplexing, Ave shall see the wise design and goodness of our heavenly Father. You recollect I told you 96 ANATOMY AND PHYSIOLOGY Union of motive and sensitive nerves. that the nerves divide and subdivide into branches so minute as to be invisible to the naked eye, and form a network over the whole body. Fre I.—Yes, Father, I recollect that, but I cannot sec that that ansAvers Frank's question, or explains the matter in the least. If, after uniting near the spine and forming one nerve, they do divide into .small branches, I suppose the fibres of each branch are .the same as the nerve Avas before it divided—part sensi- tive and part motive nerves. Father.—Yes, Frederick, that is the fact, and in (his i;3 to be seen the Avisc design of the Creator. Each branch, however minute the division, contains fibres of both the sensitive and the motive nerve, and the peculiar, and distinctive quality or character of each nerve still remains; that is, the fibres of the sensitive nerve are still sensitive, and those of the motive nerve arc still motive, (Sec Fig. 21, B, and the explanation, page 86). Now with this arrange- ment, suppose I prick'a linger, and touch one of these nerves containing fibres of both the sensitive and 1 'otive nerve, the sensitive conveys the fact to the mind; but if there were no motive nerve connected with the sensitive which I had touched, how could the mind convey back its order to the point from which the sensation or pain proceeded? That avc may sec the more clearly the wisdom and goodness of this aiTangement, we will suppose that RENDERED ATTRACTIVE. 97 Motive and sensitive nerves. the sensitive nerves of one pair is distributed to the right hand, and the motive nerves of the same pair to the left hand. In that case I accidentally place my right hand upon a hot iron. The sensitive nerves convey the fact to the mind, and the mind sends back the order to remove the hand; but as the brain or mind is not in communication by the motive nerves, with the right hand, but is with the left, the order goes off to the left hand, and I raise the left, but let the right remain on the iron. It is as if one residing in Boston, should receive a telegram from Providence, R. I., and should attempt to return an answer, but by some disarrangement of the wires, the answer goes off to New York. CONVERSATION VII. THE NERVOUS SYSTEM—CONTENDED, Sensation of an organ or part, in proportion to the number of nerates distributed upon it—the sensation greatest where most needed—objections answered—every nerve a sentinel to guard from danger, etc. Father.—At our last conversation I made you acquainted with several interesting facts in regard to the nervous system. There are others not less im- pressive, which I ha vie reserved for the present inter- Aiew. Mary.—You told us so many wonderful things about the nerves, at our last meeting, which I had neArer known before, that I thought you had said all. But I am pleased to find there are other facts yet to learn; I feel so deeply interested in the subject. Father.—In those parts of the body where sensation is most needed, the nerves are most abundant; for the sensitiveness of any part or organ is in proportion to the number of nerves distributed upon it. Frank—What need is there, Father, that one part of the body should be more sensitive than another ? Father.—For the reason, my son, that some parts or organs are used more frequently, and are more im- 98 RENDERED ATTRACTIVE. 99 Nervous sensation greatest when most needed. portant in their use than others. For example:— The inside and ends of the fingers are far more sensi- tive than any other part of the hand, because Ave need to use the fingers to ascertain the quality or condition of bodies or things, as to their being soft or hard, cold or hot, rough or smooth, etc. And this sensi- tiveness of the fingers, is precisely where it is needed —where our convenience requires it should be. For who ever thinks of feeling an article with the back of the fingers to ascertain its quality ? This sensitive- ness is very acute and accurate. By it, the blind may be taught to read, and they may also be taught many of the mechanic arts. But its great value is seen in the hourly duties of life. The mind reaches out, as it were, through the ends of the fingers and makes itself acquainted with the form and quality of every thing within reach, and appropriates the knowledge thus obtained, to the safety and welfare of the system. Frank.—Since our last conversation, Father, I have been thinking over what you told us about the sensi- tive nerves—how they were made to convey painful sensations to the mind, and that all the pain Ave ever suffer, from AAmatever cause, is on account of our having sensitive nerves, and that if we had no such nerves we should never have any pain. And you speak of this fact, as proof of the goodness of the Creator. I know that the most you have told us since we com- 100 ANATOMY AND PHYSIOLOGY Erroneous views relative to pain. menced conversing upon this subject, has been, to my mind, the clearest proof that God's goodness has caused him to make us as Ave are; but I cannot see how it can be so in this case. If God is so good, I do not see Avhy he could not have made us so that we should never have been liable to suffer pain. O ! hoAv de- lightful that Avould have been. Then, if I should burn, freeze or bruise my fingers, or flesh, I should have no pain, and if I Avere ever so sick it would cause no suffering. But noAv, if I burn my fingers, or if I freeze them, I am in such distress for hours that I don't know what to do. Or, if I am sick, I have such pain in my head, or stomach, or some other part of my body ! Or, if I get the smallest mote into my eye, the distress is dreadful. O, Father, hoAv I Avish that I had been made with- out sensitive nerves. Then, if I should go a little too near a hot stove, it would not burn me, and if I should go into the cold air on the most freezing day, I should feel nothing of it; and no matter how sick I might be, I should have no pain, and even gravel thrown into my eyes, would cause no distress. O, hoAv de- lightful it would be to live if we could have no suf- fering ! Sometimes I cat hot bread, or good mince pie, or nice, rich preserves, and it causes me such pain in the stomach, that I am sick for two or three days after. But if I had no sensitive nerves I could 'oat just what I like, and it would never give me pain. RENDERED ATTRACTIVE. 101 • Erroneous views in regard to pain. "Why, it seems strange to me, Father, that you never thought of this ! for if you had, I think you Avould not have said so much about the value of the sensitive, nerves, in our last conversation. Father.—My dear son ! you seem not only to have discovered a great improvement upon the Avorks of our heavenly Father, in the formation of our bodies, but you appear very jubilant over your supposed discovery. But do you really think, Frank, that it Avould have been an improvement in our condition, had Ave been made so as to be incapable of suffering pain ? Frank.—Why yes, Father, hoAv could it be other- wise ? Can any one be as happy Avhile suffering pain, as Avhen free from it ? You knoAv you sometimes give AA-hat you call opiates to your patients, to relieve their pain. Now, how much better it would have been if they were incapable of feeling pain. I do not knoAv, Father, but you can show that it is a good thing to suffer; but I choose to be free from it, if I can. It is true that you have cleared up some other things that looked dark, and reconciled them with your theory of goodness, but I cannot see hoAv you can do so in this case. Fred.—I have been listening, Father, to the conver- sation betAveen you and Frank, and I must say with him, that I cannot see that it proves any goodness in the Creator, to make us capable of so much pain and sufferino-, when he might have made us incapable of it by just leaving out the sensitive nerves. 102 ANATOMY AND PHYSIOLOGY Results of the incapacity for nervous sensation. Mary.—And so it seems to me, Father. Father.—Well, my dear children ! Then you have all given your verdict against me, and not only against me, but against the goodness of our Creator. Now let us examine this subject. You say that in case you had no sensitive nerves, if you should go a little too near a hot stove it would not burn you. Let us suppose that after being in the cold, you go to a stove to warm yourself; not that you feel cold, for you are incapable of feeling, but supposing your hands may be cold, you approach the stove—but not knowing whether the heat is moderate or intense—for you cannot feel—you hold out your hands to warm them, and your attention is taken from them by enter- ing into conversation with some one standing by, until you look upon your hands, and to your utter horror, you see the flesh is broiling upon the bones! Now, Avas it a favor to you, in this case, or was it kindness in the Creator, that you were made incapable of feeling either cold or heat ? Again, you say, that if you should go into the cold on a very freezing day, you would feel nothing of it. Let us suppose that on such a clay you are skating on the ice, or coasting down the hill on your sled. Beino- busily engaged in your sport, and not feeling the cold* you continue in high glee, until you find that your fingers are stiff—you cannot bend them, and soon the wrist and elbow are stiff; still, you feel no pain. But RENDERED ATTRACTIVE. 103 Want of nervous sensation and its results. what is the matter ? Why your hands and arms are frozen stiff, and when they thaw the flesh will fall off and leave the bones bare. Now, had you been capable of pain, you would not have remained at your sport in the cold. The painful sensation produced, would have driven you into a warm room, before your limbs had been frozen, and thereby you would have saved them, and perhaps your life.- Again, you say, if I had no sensitive nerves, no matter how sick I might be, I should have no pain. But if sickness caused no distress, we should feel no alarm, and of course should neglect the remedy until the disease became fatal. You say that the smallest mote in the eye causes severe suffering. But did you never think of the fact, that the eye is one of the most important, as well as most delicate organs of the body? that a very slight injury may cause its utter ruin, and that for its safety it was necessary that it should be endued with a high degree of sensitiveness,v to enable it to give the alarm of the first and slightest approach of danger? The more precious the treasure, the more carefully should it be guarded. Every pain we feel, from whatever cause, is a friendly warning of danger. It informs us that the organ or part of the body where the pain exists, is invaded by a foe, and is in danger of being destroyed. 104 ANATOMY AND PHYSIOLOGY Every nerve a sentinel.________________________ You recollect I told you that the nerves form a perfect network over the entire surface of the body. Well, every nerve is a sentinel, placed there by God himself, to guard the body from danger and death. Not a particle of the surface of the body as large as the point of a needle remains unguarded. Let a foe approach any part of the body, Avhether in the form of fire or frost, the sting of a bee, or the cut of a knife, and the sentinels (nerves) instantly convey the fact to the mind; thus, every particle of the body is guarded from the incursions of an unknoAvn foe. In sickness of every form, the pain produced, is a Avarn- ing that something is destroying the vitality or life of the part where the pain exists, and which must be removed or death will be the sure result. Thus timely warned, the proper medical treatment is applied, and death is averted. Now tell me, my dear children, whose way do you think best, yours, or the Creator's? Frank.—O, Father! I do wish that I had never said a word about it. It does seem so strange that I could not have looked ahead a little and seen the lia- bilities you have described. I will never again be guilty of thinking that I am wiser and better than the Creator. Fred.—I am ashamed, Father, that I gave approval to all that Frank said. I hope I shall some time learn my OAvn ignorance, and be more careful how I expose it. RENDERED ATTRACTIVE. 105 Nerves most numerous on the surface—the reason why. Mary.—I did not say so much, as Frank and Frederick, but I sec, with shame, that I was just as stupid and wicked as they were. Father.—We may well be ashamed, my children, when we express, or even indulge a thought, that we can make improvement on the Avorks and Avays of God. It is true, that in studying his Avorks, we shall often find what, to us, looks dark and mysterious, and what, perhaps, Ave shall find difficult to reconcile with our notions of wisdom and goodness. But let it ahvays be a sufficient answer to such thoughts and queries, that we are ignorant, and God is infinite in knoAvledge, as well as goodness. As we advance in knowledge and goodness ourselves, Ave shall see more clearly the truth of the inspired declaration—w As for God his ways are perfect." Fred.—If you please, Father, I would like to ask a question. You say the nerves form a network over the surface of the body. Are they more numerous on the surface than in other parts of the body ? Father.—Yes, my son, very much more abundant on the surface than elsewhere. Fred.—Why is that? Father.—Evidently, because the surface is the part of the body principally exposed to injury. No injury from Avithout could be inflicted upon the internal parts, Avithout affecting the external first. It was therefore necessary that the external surface should be the 106 ANATOMY AND PHYSIOLOGY The sympathetic nerves. principal seat of sensation, so as to give warning on the first approach of danger, that deep and dangerous wounds, to Avhich all, especially the laboring classes, are ahvays exposed, might be avoided. Besides the nerves I have described, there is another important system called the sympathetic or ganglionic system. It consists of a series of Gan'-gli-a, or knots, which are small masses of nervous matter, and are situated on each side of the spinal column. They are connected with both the spinal and cranial nerves. The ganglia are nervous centres, from which branches pass off and communicate Avith other ganglia situated in different parts of the body. The head, neck, and trunk, receive branches from the sympathetic, which control the circulation of the blood, the action of the arteries, veins, capillaries, lymphatics,—the function of absorption and secretion,—indeed, most of the functions of the internal organs, are carried on by these nerves, without the knowledge or control of the mind. By these nerves, all the organs of the body are connected, and such is the poAver of nervous sympathy that a healthy organ often becomes diseased, in consequence of its connection with a diseased organ by the sympathetic nerves. Thus, my dear children, we have taken a very brief and rapid view of the nervous system, by which we see that it is the nerves which connect the mind with the external world, and give us all the knowledge we RENDERED ATTRACTIVE. 107 The nerves the medium of all knowledge. have of the universe around us. Had we no nerves, we could never see the light of the sun, but total darkness would brood upon us forever. Nor should we ever hear the sweet music of the human voice, or the varied harmonies of nature. Nor should we ever have tasted the delicious products of earth, which God has provided in such profusion. All the knowledge we have of the earth around us, or of the heavens above us, is obtained through the nerves. Were it possible for the powers of the human mind to be what they now are, without the nerves, we could know nothing—either of God or his works. Shut out from the universe of God, we could have no conception of anything but our oavu isolated self, and that would be a consciousness of little Avorth. Fred.—We feel very grateful, Father, for the knowledge you have given us about the nervous sys- tem, and we have passed you a vote of thanks. CONVERSATION VIII. DIGESTION AND NUTRITION. The digestive organs—The process or function of digestion, how performed—The digestive fluids, saliva and gastric juice—Chyme and chyle, how formed—The lacteals, their function—The thoracic duct—Chyle poured into the venous blood—Review of the subject—Mastication or chewing the food, the first act of the digestive process—The act of swallowing, how performed—The glottis and epiglottis. Father.—In the previous conversations I have given you a, brief description of the bones, muscles, and nerves; or, rather, I have given some particulars in regard to them—for it can hardly be called a descrip- tion, it is so brief. These constitute the principal bulk of what is called the solids of the body. But as yet I have said nothing of the manner in which the body is formed, or what sustains it in existence. The body is made up of a great number of organs and parts, differing greatly in their functions, yet all acting harmoniously, and each contributing to form the most wonderful and perfect piece of mechanism ever produced. But how is this machinery formed ? Whence comes the materials? And what power moulds them into 108 ANATOMY AND PHYSIOLOGY. 109 How the body is formed. form? Why is one part solid bone, another muscle, another nerve, another membrane? and all in due proportion. The question to which we are to give particular attention at the present time, is,—What are the mate- rials out of which our bodies are made, and by what process they become bone, muscle, nerve, and the great variety of parts which compose the system? If we enter a cotton mill, we look with pleasure and surprise, at the thousands of spindles and looms, and other machinery, moving with great rapidity and accuracy. But a careful examination will show that every part is made, or formed, by mechanical means, and upon well known mechanical principles. But not so with our bodies. The knife, the plane, the hammer, have never been brought into use in forming this wonderful structure. Fred.—Why no, we knowihat our bodies are not made with tools, the same-as you would construct a house, or a cotton mill. Our bodies grow. Father.—But how do they grow, my son? Fred.—Why I don't knoAv how, but I know they prow, for boys grow up to be men. And you know that I am a great deal taller than I Avas when Mary was born. I suppose we grow because we eat good food. You know you have often told us that neAV milk and bread made us grow finely. I don't think I should grow much if I did not eat. You know that 110 ANATOMY AND PHYSIOLOGY Uow the body is formed. ___________________ John Scott, who was so sick all last summer, and could not eat anything, did not groAv at all, and be- came very thin. Father.—It is true, my son, that we live by eating food. But how can food, such as bread and milk, rice, and toast, make bone, muscle, etc. Is there any similarity betrween bread and bone, or milk and muscle ? Fred.—I cannot see that there is, Father. I never thought of that before. I have always been eating and growing, and ahvays thought that somehow good food made me grow, but I do not know how; I wish you would tell us. Father.—The food we eat, such as bread, meat, fruits, and vegetables, is converted into living human bodies, by the wonderful process called digestion. Fred.—But, Father, how can food be converted into living human bodies ? Father.—I do not mean to say that food, itself, becomes living bodies, but it contains Avhat is called elementary principles, out of which our bodies are formed. Fred.—Will you explain to us hoAv it is done ? Father.—I will give you, briefly, the substance of what is known about it. But this, like all the Avorks of God, has limits beyond Avhich human investigation cannot go. You must always bear in mind, my chil- dren, that when we study the works of the Creator, RENDERED ATTRACTIVE. Ill The digestive organs. we see only a few of the plainest and most obvious facts, and that beyond all that can be discovered by the most profound scrutiny, lie mysteries as incom- prehensible as the Deity himself. And yet, strange to say, these mysteries are so common that we seldom or never think of them; constantly before our eyes, yet we never see them; in every part of our bodies, but we never contemplate them. But I Avas about to say, that there is a set of organs,. or an apparatus, in our bodies, the office or function of which is, to produce the changes in our food, of which I have spoken, and without which, food could no more nourish us, and cause us to grow, than saw- dust or gravel. They are called the digestive organs. Frank.—Will you please tell us what the digestive organs are? Father.—They are the Mouth, Teeth, Sal'-i-va-ry Glands, (E-soph'-a-gus, (Gullet—passage to the stom- ach) ; Stom'-ach, In-tes'-tines, (Bowels) ; Lac-te-als, Tho-rac-ic Duct, Liver, and the Paii-cre-as. The Mouth is the cavity which contains the organs of taste and the instruments of mastication. It is bounded on each side by the cheeks ; in front by the lips ; above by the hard palate, (roof of the mouth) ; and the teeth of the upper jaw; below, by the teeth of the lower jaw and the tongue ; behind, by what is called the soft palate, Avhich may be elevated or de- pressed at pleasure, so as to close, or leave open, the passage to the stomach. 112 ANATOMY AND PHYSIOLOGY The stomach, liver, bowels, etc. Fig. 23. A GENERAL IDEA OF THE STOMACH, LIVER, BOWELS, ETC. Fig. 23. 9, the stomach; 10,10. the liver; 1, the gall bladder; 2, the duct which conveys the bile to 4,4 which is the duodenum; 3. the pancieas; 5, ihe ces-ophasus; A, the duodenum; B, the bowels; U, the junction of Ihe i-mall mtexliues with the colou; D, the appendix vcrmiformis: i\, the coecunv F the ascenumg colon; G, the transverse colon; 11, the descending colon • I ihe si"- noid flexure; J, the rectum. ° As I intend, at some future time, to give you a someAvhat lengthy description of the teeth, I shall say nothing here in reference to them. RENDERED ATTRACTIVE. 113 The salivary glands. Fig. 24. A VIEW OF THE SALIVARY GLANDS IN THEIR PROPER SITUATION. Fig. 24. 1, the parotid: 2, its duct: 3, the submaxillary gland: 4, its duct. 5, the sublingual gland. There are six salivary glands—three on each side— called the pa-rot'-id, the sub-max'-il-la-ry, and the sub-lin'-gual. Several small ducts, connected with these glands, open into the mouth, for the passage of the saliva. The (Esophagus is a large tube extending from the back part of the mouth, or the pharynx, to the stomach. It is situated behind the trachea, heart and lungs. Its function is to convey the food to the stomach. The Stomach has been compared in form, to a musical instrument called the bag-pipe. It is situated at the upper part of the abdomen, or bowels, a little to the left of the medial line, just below, and in im- 114 anatomy and physiology The stomach and bowels, a description of._______________ mediate contact with what is called the diaphragm. It has two openings, one for the reception of food, connected with the oesophagus, called the cordiac orifice; the other connects Avith the duodenum—the first portion of the intestine—and is called the pyloric orifice. These two orifices are at the opposite ends or extremities of the stomach. The stomach is composed of three coats or mem- branes. The exterior, is very strong and tough, and by its connection Avith surrounding parts, keeps the stomach in its proper position. The middle coat is composed of two layers of muscular fibres, one set of which is arranged lengthwise, the other circularly. The inner is called the mucous coat, and is arranged in folds. The stomach is abundantly supplied Avith small glands which secrete the gastric fluid, which is the great agent, or instrument, in the process of digestion ; a description of Avhich, I shall soon give you. The Boavels.—Connected Avith the stomach, is a long tube, called the intestine, or boAvels, divided into two parts—the small and large. The small in- testine is about twenty-five feet in length, and is diA'ided into three parts, called the Du-o-de'-num, the Je-ju'-num, and the Il'-e-um. The large intestine is short, compared Avith the small, being about five feet in length, and like the small, is divided into three portions, namely, the Cce'-cum, the Co-Ion, and the Rec'-tum. RENDERED ATTRACTIVE. 115 The small intestine. Fred.—You surprise me, Father ! The intestines thirty feet long? What need is there of such length, and how can they be kept.in place ? Father.—These are questions of interest, my son, and Ave will duly consider them, after I have given a description of the different parts. The Duodenum is connected Avith the stomach at the pyloric orifice, as I before stated. It is larger than the other small intestines, and in length, is about the breadth of twelve fingers. It terminates in the jejunum. Ducts from the pancreas and liver open into it about six inches from the stomach. Frank.—You say the small intestine is divided into three parts. Is there any mark to distinguish the termination of the one, and the commencement of the other ? Fathar.—There is not. The one is continuous with the other. The Jejunum is continuous with the duodenum. It is someA\mat thicker than the other small intestines, and different in color, having a pinkish hue. The Ilfxm is paler than the jejunum—it is also smaller, and thinner in texture. It terminates by a valvular opening into the colon, forming an obtuse angle. By this arrangement, substances are prevented from passing from the colon to the ileum. 116 anatomy and physiology Uow the bowels are kept in place. The Ccecum is merely a pouch, a few inches in length, at the commencement of the large intestine. The Colon is an important part of the large intes- tine. It is divided into three parts—the ascending, transverse, and descending. It terminates at the rec- tum, Avhcre it makes a cuiwe upon itself, called the sig'-moidflex-are, Avhich, in the function of the bowels, is of great importance. The Hectum is the termination of the large intes- tine, Avhich, like the smaller, and the stomach, has three coats, or is formed of three membranes. The mouth, gullet, stomach, and intestine, consti- tute Aviiat is called the alimentary canal. I Avill iioav ansAver your queries in regard to the length of the intestine, and hoAv it is kept in place. I must first state, hoAvevcr, that there is a thick sheet of membrane, called the mes'-en-ter-y, formed of several folds of the peritoneum—(lining mem- brane of the abdomen), spread out from the vertebra, like a fan. The boAvels arc attached to the edges of this membrane, and held by it in their place. As to the length of the intestine, it does seem a wonder- ful thing that it should be about six times the length of the body. But a careful study of the subject, Avill, I think, reveal to us, both the object and necessity of such an arrangement. rendered attractive. 117 Length of the intestine—why so long. Comparative anatomy reveals the fact, that the length of the intestinal tube, in different species ol animals, is governed by the kind or quality of food upon Avhich they subsist; the intestine of the carniv- erous, or flesh eating animals, being the shortest, and the herbiverous the longest. In some birds of prey, the intestinal canal is but a little longer than the body of the bird. In the wild-cat it is about three times its length, Avhile the intestine of a sheep is thirty times the length of the body. The longest is in the deer kind, measuring, in some cases, ninety-six feet. But man, being omniverous, living upon a mixed diet composed of both animal and vegetable, holds a medium position, and in him, therefore, we find it of medium length. Fred.—But why does the land of food upon which animals subsist, render it necessary that the intestine should vary so greatly in length ? Father.—For the reason that it requires a much greater bulk, and consequently a much longer time to digest, and obtain the nutriment from herbs and grass, than from flesh, and therefore the former require to be retained longer in the alimentary canal, to per- fect the digestion, and allow time for the absorption of chyle by the lacteals. But, Avhen the food is readily digested, and the chyle or nutriment is soon elaborated and made ready for absorption, as animal food is, its long retention is 118 ANATOMY AND PHYSIOLOGY Uow the intestine is held in place. unnecessary, and might be injurious ; consequently a long alimentary canal is not needed. Fred.—I think I understand it now. But I cannot imagine hoAv the small intestine, of such length, can be kept in place. Father.—It would seem a difficult matter, as it is a soft substance, yielding readily to pressure ; some portions of which are laid in folds from side to side, others in oblique and circuitous directions ; it must, Avithout some extra precautionary measure for its safety, be constantly liable to displacement by the numerous, violent", and abrupt motions of the body; or be bruised and Avounded by every fall; or it would become entangled with itself, or shaken out of its proper position; and the order which is necessary to enable it to carry on its important functions. Now all this danger, so serious in its nature, and which might be fatal in its results, is provided against in the following manner, which is as admirable as it is beneficial. Throughout its Avhole length, the intestine is firmly attached to the mesentery, being "gathered on" to it as a ruffle to a garment; it being not more than one- fourth the length of the intestine. The mesentery not only keeps the intestine in its proper place and position, but sustains the numerous small arteries, veins, lymphatics and lacteals Avhich lead to and from every part of the coats and cavity of the intestinal RENDERED ATTRACTIVE. 119 Functions of the liver. Fig. 25. THE LIVER. Fig. 25. 1. the right lobe; 2, left lobe; 3, 4, small lobes; 10, gall bladder; 17, the notch into which the spinal column is fitted. canal. This membrane, which thus supports the ali- mentary apparatus, is itself supported by being firmly attached to several of the spinal vertebra. The Liver is the largest gland, and, indeed, the largest organ in the system. It weighs about four pounds. It is situated below the diaphragm, in the right side, and has several lobes. It is concave on the under, and convex on-the upper surface, and is retained in its place by several ligaments. Its office or function, is tAvo-fold,—the secretion of a fluid called bile—important in the digestive process,—and the separation of impurities from the venous blood. There is a membranous sac, called the gall cyst, or bladder, on the under side of the liver, Avhich acts as a reservoir for the bile. A duct, from it, through Avhich the bile is discharged, opens into the duodenum. 120 ANATOMY AND PHYSIOLOGY Function of the pancreas, diaphragm, etc. THE PANCREAS. " The Pancreas is a long, flattened gland, analogous to the salivary glands. It is about six inches in length, weighs three or four ounces, and is situated trans- versely, or across the posterior wall of the abdomen, behind the stomach." Like the liver, it is connected to the duodenum by a duct, whose mouth opens on its inner surface, through which the pancreatic juice flows. The Omentum, (call), is formed of four layers of serous membrane, connected Avith the stomach and transverse colon. It contains adipose matter. Its function is to protect the intestines from cold, and facilitate their movements upon each other. The Spleen, (milt), is an oblong, flattened organ, of a dark, bluish color, situated in the left side, under the diaphragm, and in contact with the stomach and pancreas. It Avas supposed, by the ancients, to be the seat of melancholy. What function it performs is not known, but there are various conjectures, in regard to its office in the animal economy. RENDERED ATTRACTIVE. 121 Process of digestion described. The Diaphragm, or Midriff, is a muscular mem- brane, which separates the thorax from the abdomen. The oesophagus, aorta, and vena cava pass through it. Its functions are various ; the most important of which, perhaps, is the aid it affords the lungs in the act of respiration or breathing. The Thoracic Duct commences in the abdomen, in front of the lower portion of the spine. It passes through the diaphragm, and rises to the neck. It lies in front of the spine, by the side of the oesophagus and aorta,—a location which protects these important vessels from injury. It is formed by a union of the lacteals, and is about the size of a goose-quill. It terminates at the point where the principal vein of the left arm, called the subclavion, unites Avith a large vein in the neck, called the jugular. At this point, there is a pair of semilunar valves, the object of Avhich is, to prevent the venous blood from flowing into the thoracic duct;—another proof of the kind care of our Creator. Having given a brief description of the principal organs concerned in the digestive process, I will now describe the function itself. Digestion, strictly speaking, is that process by Avhich food is converted into blood. It commences Avith the mastication and insalivation of the food in the mouth. Frank.—What do you mean, Father, by mastica- tion and insalivation ? 122 ANATOMY AND PHYSIOLOGY Mastication, insalivation, saliva. Father.—Mastication is the cutting, or grinding of the food by the teeth. The process is necessary in order to prepare the food for the action of the digestive fluids. Insah\'ation is the admixture of the food in the mouth, during mastication, with a fluid called saliva. It is the first of the digestive fluids, and is secreted by the salivary glands, which I have already described. Mary.—What are glands, Father? Father.—They are bodies or organs situated in dif- ferent parts of the body, the function of which is to secrete, or separate from the blood, peculiar fluids, some of which fulfil very important offices in the ani- mal economy. But as I intend to give you a more detailed account or description of these organs, I will here only say, that the salivary glands secrete saliva, or spittle, the object of which is to moisten the food in the mouth. A fact worthy of note is, that the saliva is not secreted with uniform rapidity at all times. While the tongue and jaAvs are at rest, and while fasting, the quantity secreted is but small. But the action of the jaws in masticating the food, increases the flow, par- ticularly if the food has a decided taste. The secre- tion of saliva is great also Avhile masticating dry food, as a cracker, and little or none is secreted while eating fluids, as broth or milk. After mastication and insalivation, the food passes RENDERED ATTRACTIVE. 123 The lacteals and their function. into the stomach, where it meets with a powerful and penetrating fluid called the Gastric juice. This fluid mixes with, and disolves the food, forming it into a soft, pulpy mass, called chyme. It then passes out of the stomach, through the pyloric orifice, into the duodenum. It there meets and mixes with the bile, or gall, which is a yellow, or deep green, and very bitter fluid, secreted by the liver, and poured into the dnodenum through a large tube or bile duct, as I have already explained. While in the duodenum the chyme is also mixed Avith another fluid called the Pancreatic juice, secreted by the pancreatic glands. By the action of these two fluids, the nutritious portions of the food are separated from -the innutritious. The nutritious portion is called Chyle, and in color and consistence, resembles thin cream. The Lacteals. As the chyle passes along the in- testine, it is absorbed, or taken up by vessels called Lac'-te-als, whose mouths open on the inner surface, or mucous membrane, of the small intestine. The lacteals pass between the membrane of the mesentery, and through successive ranges of small bodies called mesenteric glands. A large number of the minute lacteals enter the first range of these glands, and a less number of larger ones pass from the first to the second range, and after passing through several successive ranges of these glands, diminishing in 124 ANATOMY AND PHYSIOLOGY Mesenteric gland and lacteals. Fig. 27. THE MESENTERIC GLANDS, WITH THE LACTEALS PASSING THROUGH THEM. Fig. 27- 1, is the intestine; 2, 3, 4, the mesenteric glands through which the lacteals pass; 6, the thoracic duct; 7, the spinal colamn; 8, the diaphragm. number and increasing in size, they finally enter, and pour their contents into the thoracic duct, (See Fig. 27, which, study carefully). The lacteals are very numerous, there being mil- lions of them, and are less in size than the smallest hair, being invisible to the naked eye, and can be seen only Avith the aid of the microscope. They run to- gether, as I have said, and form tubes larger and larger, until they all concentrate in one large tube, the Thoracic Duct, which I have already described. The quantity of chyle taken up by the lacteals in a healthy man, is estimated at from tAvo to three quarts per day. Frank.—If you please, Father, I wish to ask why RENDERED ATTRACTIVE. 125 Why the lacteals are so small. the lacteals are so very small, when the quantity of chyle which passes through them is so great. Father.—To answer your question, I must first state, that their are millions of blood-vessels in our bodies, so small that three thousand can lay side by side and not extend more than one inch. Now, as the chyle is to be poured into the blood, as I shall hereafter explain, were not the lacteals as minute as these blood- vessels, they might absorb, or take up particles of food so large as to choke up these small blood-vessels, and thus prevent the circulation of the blood, which would cause immediate death. Our Maker knew this, as he made both the lacteals and the blood-vessels, and therefore formed the lacteals so small that they can take up no particles that can obstruct the circulation. Frank.—Your answer is very interesting, and gives me information of what I knew nothing about before. How clearly it shows the goodness and Avisdom of the Creator, and the perfection of his work. Father.—-It does. But I Avas going to say that the chyle taken up by the lacteals, is poured into the thoracic duct, which conveys it into the veins, where it mingles with the venous blood, and with it is conveyed to the heart, and by the action of the heart and lungs, which I shall hereafter explain, becomes blood, en- dowed with all the qualities of life. But this is a very brief description. Let us now review, and enlarge upon what we have been saying 126 ANATOMY AND PHYSIOLOGY Mastication and digestion upon the subject of digestion, and see if we can dis- cover anything in it that speaks of the goodness and careful kindness of the Creator. The first act in the digestive process, as we have seen, is the mastication or cheAving of the food, so that the digestive fluids can act upon it. This renders it necessary that a suitable apparatus for the purpose, should be provided. And Avhat can be more admira- bly adapted to the purpose than the teeth, tongue, cheeks, etc. The large, broad teeth, on each side the mouth, do the grinding, while the tongue on the inside, and the cheeks on the outside, serve to keep the food upon, or between the teeth until the grinding is accom- plished. At the same time, the movement of the jaw in chewing, stimulates the salivary glands to secrete, and pour into the mouth, a quantity of saliva, for the purpose of moistening the food. That we may see the value of this apparatus, and the goodness of the Creator in providing it, let us suppose that we are made Avithout teeth, or any thing as a substitute. Without nutriment from food Ave should soon pine away and die. That we may obtain nutriment from it, it must be digested. That it may be digested, it must be masticated; but how can it be masticated without teeth ? Again, Avere it possible to eat food without teeth, the great pleasure which people enjoy in eating, Avould be principally lost; for the rich, delicious taste of RENDERED ATTRACTIVE. 127 How food is conveyed to the stomach. food, is obtained mostly by chewing it. But how could we cheAv without teeth ? Frank.—I think, Father, that I shall value my teeth more than ever, and I trust that I shall be more grateful to my heavenly Father for them. Father.—I hope you will, and will love him more and more. Another very interesting fact, is the manner in which food is conveyed from the mouth to the stomach by the act of swallowing. It is as follows :—There are two passages from the mouth to the thorax, or chest,—one for the food, called the cesophegus or Fig. 28. A SIDE VIEW OF THE FACE, (ESOPHAGUS, AND TRACHEA. Fiff 28 1 is the trachea; 2, the larynx ; 3, the oesophagus; 4,4, 4, muscles of^thge pharynx ;o! the muscles of the/cheek; 6 the muscle which surrounds the mouth; 7, the muscle forming the floor of the mouth. 128 ANATOMY AND PHYSIOLOGY The act of swallowing, how performed.__________. gullet, which I have before described, the other, for the passage of air into the lungs, called the trachea, or windpipe. These passages are so arranged, that the windpipe is placed in front of the gullet,—the passage to the stomach. It is, therefore, necessary, that every particle of food and drop of liquid, that passes from the mouth to the stomach, should, by some means, be conveyed over the upper end, or mouth of the windpipe ; and it is also necessary that the Avindpipe should be kept open to admit the free passage of air into, and from the lungs, in the act of breathing. Now, how can these two important objects be ac- complished, without interfering with each other? If the windpipe is kept open, how can food and liquids pass over it into the stomach, without going into it? If it is not kept open, how can the air pass freely to and from the lungs ? Fred.—I cannot answer that question, Father, for I cannot think of any way by which it can be done. But I have seen enough, in what you have told us, to assure me, that our Maker can do any thing that is necessary, hoAvever impossible it appears to us. Will you please tell us how it is done ? Father.—You are right, my son. God can do whatever he pleases, and will do Avhatever is necessary. The plan he has adopted in this case, and the apparatus he has made for its accomplishment, is a wonderful piece of mechanism, Avhich I will attempt to describe. RENDERED ATTRACTIVE. 129 The epiglottis a safety valve; its mode of action. The upper end, or mouth of the windpipe, called the Glot'-tis, is covered by a cartilage, called the Ep1- i-glot-tis, Avhich is a sort of valve, or lid, fitted to the glottis so perfectly, that Avhen closed, it is impossible for a particle of food, or a drop of fluid to pass into the windpipe. Fred.—It is certainly a good way to have a valve to close over the mouth of the windpipe, but what closes and opens the valve at just the right time ? Father.—This valve is hung, or connected with the- parts, by springs made of cartilage, and in its natural condition, is open, and admits the free passage of air to the lungs. These springs are so arranged, that the act of sAvalloAving presses down the valve before the food or fluid gets to it, perfectly closing the passage to the lungs, and leaving the passage to the stomach free and clear, and as soon as the food is passed over the epiglottis, or valve, it opens again of its own accord, and remains open until closed again by the act of swaUoAving. This is a perfectly self-regulating safety valve, being closed by the same action of the muscles that carry the food into the stomach in the act of swallowing. Now is not this a wonderful arrangement? And just think, this perfectly safe action of the epiglottis, upon AA'hich our safety depends, takes place without the least thought on our part. Had its action been left to our care, how long do you think we should 130 ANATOMY AND PHYSIOLOGY Perfect action of the epiglottis. __________________ live* How often we should attempt to swallow, and forget to close the passage to the lungs, and thus pro- duce strangulation, by allowing food to pass into the lungs. Life and death are suspended upon the timely closing and opening of the epiglottis. Fred.—How impressive this fact! It seems to me, that no one can become acquainted with such proofs of God's kind care for us, without feeling sincere and fervent gratitude. But, does not the food sometimes get by this valve, into the windpipe ? I have sometimes heard people say that the " food went dovni the wrong way." And I recollect that once little sister was crying while eating, and some food was drawn doAvn the windpipe with the breath, as mother said; and it caused such coughing and strangling that we feared she would die. Now did not the food go by the valve ? Father.—I think that food never passes into the windpipe in the act of swallowing. But if people talk and laugh, and children cry, with the mouth full of food, particles of it may be drawn in with the breath. But this proves no fault in the structure of the valve, nor does it show any imperfection in its action; it simply shoAVs the imprudence of talking and laughing while eating. And this leads me to speak of another interesting fact. To draw particles of food, or any other solid RENDERED ATTRACTIVE. 131 Sensitiveness of the windpipe. substance into the lungs^ endangers life. But our Maker, knowing that we might accidentally, as I have just described, inhale irritating substances, hasjiro- vided a safe-guard, which is this :—The lining mem- brane of the windpipe is endowed with the most acute sensitiveness, so that the presence of particles of food, or any other substance, causes the most violent cough- ing and spasm, and thus gives warning of the presence of an enemy that endangers life. And yet this same sensitive membrane is totally insensible to the pres- ence of air, which is constantly passing over it to and from the lungs. There must certainly be a wise design in this, and it is as good as wise. This sensitive membrane may be regarded as a sentinel, placed there by the Creator, to give instant warning of danger. And hoAv well he performs his duty, every one knows who has had the misfortune to draw a particle of food into the windpipe. But Ave must now close this conversation which has already been too long, and resume the sub- ject at our next meeting. CONVERSATION IX. DIGESTION AND NUTRITION--CONTLNUED. Quantity of gastric juice secreted—Its power to dissolve food—Peristaltic motion—Office of the bile and pancre- atic juice. Father.—As I have before said, the gastric juice is the great agent or instrument in the process of diges- tion. This fluid has the power of dissolving food of all kinds with which it comes in contact. It is not found in the stomach at all times, but is secreted at the time of taking food; the food, as it comes into the stomach, acting as a stimulant to the secreting glands. The quantity of gastric juice secreted daily in a man's stomach, is supposed to be not less than fourteen pounds. Frank.—How can that be ? Can the stomach con- tain fourteen pounds of fluid? Father.—No, it can hold but two or three pints at a time. Frank.—What then becomes of fourteen pounds? Father.—The gastric juice does not accumulate in the stomach in large quantities, but each portion, as 132 ANATOMY AND PHYSIOLOGY. 133 Peristaltic motion of the stomach. soon as it has produced its effect upon the food, is re- absorbed and taken into the circulation, and thus gives room for new secretions of the fluid to continue its action upon the remaining undigested food; and this process goes on until the food is all dissolved, when there will be found but little gastric juice in the stom- ach, and but little or none will be secreted until food is again taken. The digestive process is greatly aided by what is called the per-is-tal'-tic motion of the stomach. This motion is produced by the alternate contraction and relaxation of muscular fibres running both lengthwise and around the organ. This motion of the stomach brings the food in contact with the mucous membrane, and each portion is mixed Avith, and is dissolved by the gastric juice, and forms a soft pulpy mass called chyme, as I have before stated. The food is not all dissolved at once, but as fast as it is changed into chyme, it passes out of the stomach, by the pyloric orifice, into the duodenum, and this process continues until the food is all dissolved, after Avhich the stomach rests until another meal is taken. As I have before stated, the chyme in the duode- num is mixed-with the bile from the hver, and the pancreatic juice from the pancreas, and by the action of these fluids, the nutritious portions of the food are separated from the innutritious. Fred.__How can these fluids produce this effect? 134 ANATOMY AND PHYSIOLOGY Action of digestive fluids. Father.—I cannot tell. It is one of those acts of the Creator Avhich is beyond the comprehension of man. It is knoAvn that the gastric juice in the stomach dissolves the food—that the bile and pancreatic juice in the duodenum, separate the nutriment from the gross portions, that the chyle is taken up by the lac- teals, and, by a process which I shall hereafter ex- plain, becomes blood. But how it is done I cannot tell. Why these different fluids act with such power upon the food, and Avith such different results, each pro- ducing precisely the effect needed, can be explained only by saying, that the Creator knew these effects must be produced, that our bodies might obtain the nutriment upon Avhich, not only our groAvth, but our life depends; and, therefore, endowed these organs with the necessary power to secrete the fluids adapted to produce the results I have named. Now all this action of the digestive process Avhich I have been de- scribing, like the action of the epiglottis, and other organs, which I have before explained, is no more under our control, and depends no more upon our will, or any effort we can make, than the rising and setting of the sun. All that we can do, from begin- ning to end of the process of digestion, is to select, chew and swallow our food. These are voluntary acts of ours. All else is zVivoluntary, and is governed by the laws that control all involuntary action. RENDERED ATTRACTIVE. 135 '_______________ Digestion, its abuse. And how seldom we think of what is going on within us, and the momentous consequences depend- ing upon the faithful performance of the digestive function. We take our supper, and retire, and while our bodies are being refreshed with quiet slumber, and our senses are locked in sleep, the digestive organs are busily at work, and before waking in the morning, the nutri- tious portions of the food taken for supper, are formed into blood, and are coursing through our veins, giving life and vigor to our bodies. Fred.—I feel very thankful, Father, for the infor- mation you have given us upon the subject of diges- tion ; and I think we all have great cause to be thankful to our heavenly Father, that he has so formed the digestive organs, that they do their labor Avithout our care. It seems so strange to me, that I have never seriously thought of these facts before ! I wonder if every one is as stupid, in regard to these things, as I have been. Father.—I do not know, my son, how that is. But from what we see of the community, it would not, perhaps, be harsh judging to say, that most persons are chiefly desirous to get good food—that which is rich and delicious in taste, and after it is swallowed, they think no more of the change that must be pro- duced upon that food by the digestive process, before it can nourish the system,—of the labor that is going 136 ANATOMY AND PHYSIOLOGY Hunger explained. on within their own bodies, to prepare that food to nourish and sustain, rather than destroy life, than they think of Avhat is going on in the moon. The most that many seem to think in regard to their food is, whether it has a good flavor, and rich taste ; not whether it is such as can be digested, and contains healthy nutriment. Mary.—I think it is so, Father. But how thankful we should be, that our Maker has so formed the diges- tive organs, that they perform their duty whether we think of it or not. Father.—There is another fact, in regard to diges- tion, that I must name. The digestive apparatus not only digests the food, but it gives due notice when the supply is out and more is needed. The sensation that we call hunger, is simply a demand of the system for food. Without it we could never know when our bodies were in real need of nutriment. How kind it was, then, in our Maker, so to form these organs, that they give timely notice when food is needed. For the appetite would always be a safe guide in regard to both the quantity of food and the time of taking it, had it not been perverted by vicious indulgence. When food is needed, the stomach sends up a tele- gram to "head-quarters," giving information that something is needed " down here,"—thus calling atten- tion to the subject. RENDERED ATTRACTIVE. 137 Facts about digestion. The mind not only perceives that something is needed, but the telegram (sensation) informs the mind what is needed, and food is at once ordered. Frank.—This is all very interesting and instructive. But I wish to ask if the digestion of food ever causes pain in the stomach ? Father.—No, indeed ! Digestion, on the contrary, produces a pleasurable sensation throughout the sys- tem. Why did you ask that question, Frank? Frank.—Because I have heard people complain of pain in the stomach, and I wished to know what caused it. Father.—When there is pain, in the stomach, it is usually caused by indigestion. Frank.—What causes indigestion, Father. I rec- ollect you told us that the gastric juice had the power to dissolve all kinds of food. Father.—And so it has. But here is a fact that you should know, and should never forget. The stomach secretes just enough of gastric juice to dissolve the quantity of food the system requires for nourish- ment, and no more. Now, if a man requires but one pound for a meal, and eats two, what will be the result ? Frank.—I suppose one pound will be dissolved, and pass out of the stomach, and the other will remain in the stomach, undigested. 138 ANATOMY AND PHYSIOLOGY Excessive eating. Father.—That is correct. Now, suppose ho eats two pounds more at the next meal. . Frank.—He would then have three pounds in the stomach. Father.—"When the system required but one, and when there was gastric juice sufficient to dissolve or digest but one. Do you wonder the man had pain in the stomach? And this is the course that thousands pursue, year after year, eating double the quantity of nourishment the body demands, or the digestive fluids can dissolve. Not only is the quantity twice what it should be, but the same meal is often composed of a great number of different articles, so compounded as to render them extremely indigestible. But as I intend, at some future time, to speak at length upon the subject of diet and digestion, I will here just add, that the only part God has permitted man to take in the process of digestion,—that of selecting, chewing and swallowing his food, is often so grossly abused, that lingering and painful sickness, and sometimes even death, pays the penalty of the abuse. Frank.—But what becomes of the food in the stomach that remains undigested ? Father.—It either becomes acid or putrid, and passes off in a crude, acrid state, proving a som-ce of irritation to the whole alimentary canal. And all this, because our Maker, in great kindness, RENDERED ATTRACTIVE. 139 Pleasure of eating. has connected the eating of food, with a great degree of pleasure; and man, in base ingratitude, has well nigh forgotten that food was designed for any other purpose than to please the taste. But we will leave this subject for the present and resume it at a future conversation. CONVERSATION X. THE BLOOD-VESSELS AND LUNGS. The heart—The arteries—The capillaries—The veins—Changes in the color of the blood—tlie organs of respiration or breathing, description of, function of—oxygen taken up BY THE BLOOD—CaRBON THROWN OFF BY THE LUNGS—QUANTITY of air inhaled and oxygen absorbed—quantity of carbon exhaled—Carbon, how generated—Carbon the food of veg- etables, ETC. Father.—At our last meeting I made you acquainted with some facts relative to the very interesting process of digestion, commencing Avith the mastication of the food, and speaking very briefly, of all the changes that take place, until the chyle is poured into, and mixed with the venous blood. I Avish iioav to say, that this laborious process of digestion of which we have spoken, has done nothing as yet, towards supplying the system with nutriment. Were it to stop here, Ave should as surely and as quickly die of starvation, as if we had not tasted a morsel of food. All that has been done by the entire process which I have described, is to form the blood. And the blood now contains all the elements of nutri- tion which existed in the food previous to digestion. 140 ANATOMY AND PHYSIOLOGY. 141 Vessels for circulating the blood Now, an entirely new, and totally diflerent process must take place, before the body can receive nourish- ment, Avhich consists in the conversion of blood into bone, cartilage, muscle, nerve, membrane, etc., and also the repairing the waste of the body, which is going on in every part of the system during every moment of life. That the blood may nourish the whole system, it must be conveyed to every particle and fibre of the entire body. And this requires ducts or channels, in which the blood can flow ; and some effectual means of driving it through them, all of which are provided, and Avhich I will proceed to describe. The apparatus for circulating the blood, consists of four parts, each differing greatly from the other, viz: 1st. The heart;—a large, hollow, muscular organ, which receives the blood from the veins, at one orifice, and drives it out at another, at the opposite side, into the arteries. 2d. The arteries;—tubes which convey the blood from the heart to all the different organs and parts of the body. 3d. The capillaries ;—extremely small vessels which intervene between the minute arteries and veins, and form a connection betAveen the two. 4th. The veins ;—a set of vessels which collect the blood from the capillaries, and convey it back to the heart. 142 ANATOMY AND PHYSIOLOGY Organs of respiration. In the arteries, capillaries, and veins, the blood varies greatly in quality and color. In the arteries it has a bright scarlet color, but in passing through the capillaries, it loses its bright color, and becomes darker, and in the veins it is a deep purple, and in some parts of the body, nearly black. Fred.—What causes these changes in the color of the blood, Father? I thought that blood was ahvays red. Father.—That you may understand the cause of the changes which take place in the quality and color of the blood, as it circulates through the system, you must knoAv the structure and function of the respira- tory organs; and this I shall make the subject of the present conversation. The organs of respiration, or breathing, are the Lungs, (lights), the Tra'-che-a, (windpipe), the Bron'- chi-a, (divisions and sub-divisions of the windpipe), and the Air-cells at the extremities of the bronchia. The Lungs are situated in the chest or thorax. They are conical in form, and are divided into right and left, the heart being situated between them. The right lung is divided into three lobes, and the left mto two. The right is larger than the left. The lungs are separated from each other by a mem- brane, or partition, called the Me-di-as-ti'-num. They are of a pinkish grey color, mottled. RENDERED ATTRACTIVE 143 The lungs. Fig. 29. THE LUNGS. Fio- 29 111 the rieht lung; 2, 2, 2, the left lung; 4, the windpipe; 5, the righfbfonchiai tube? efthclett bronchial tube; 7, small bronchial tu'bes; 9, 9, 9, 9, 9, 9, air-cells. Each lung is enclosed with a serous membrane, called the Pleu'-ra, which is reflected upon, and lines the chest. When this membrane is inflamed, the dis- ease is called "pleurisy." The lungs are formed of minute divisions of the bronchial tubes, the air-cells, lymphatics, arteries and veins, connected by cellular tissue, which constitute the Pa-ren'-chy-ma. 144 ANATOMY AND PHYSIOLOGY Air-cells, very numerous. The lungs are retained in place by the pulmonary arteries and veins, bronchial tubes and vessels, and pulmonary nerves. The Trachea extends from the larynx, (which is, indeed, the upper part of the trachea)—to the third dorsal vertebra. At this point, it divides into two parts, called bronchia. I will describe the structure of the trachea and bronchia, when I explain their functions. The number of air-cells in the lungs is almost in- conceivable. They have been estimated as high as one thousand seven hundred millions. Were the inner surface of these cells spread upon a plain, or level surface, the aggregate, or whole extent, would be more than thirty times greater than the surface of the whole body. Fred.—Why, Father, you surprise me by such a statement, as you have often done before ! But what benefit is such a great number of air-cells, and such an extent of surface ? Father.—This structure of the lungs is as benefi- cial as it is Avonderful, and I Avill explain it at the right time. But that you may the better understand it, I must first acquaint you with other facts. * The Trachea, or Windpipe, is made up of rings formed of cartilage, and placed near each other, form- rendered attractive. 145 The windpipe, why made of cartilage. ing a continuous tube which is kept open by the hard and firm nature of the cartilage. You can feel the hard, bony structure of the windpipe by placing the fingers on the throat. Noav tell me, my children ; can you assign any good reason Avhy the windpipe is made of hard, bony rings, and the gullet, which conveys the food to the stomach, is soft and yielding, and is always closed, or collapsed, only when it is opened by the passage of food ? Fred.—I suppose it was made in this fashion that we may breathe and talk easily. • Frank.—I cannot think why it was made so, unless it was that we might laugh heartily. Mary.—Well, Father, I think it was so that we might sing, clearly. Father.—Do you not see, if the windpipe was soft and yielding, like the gullet, that when we draw in breath, the sides of the pipe would be drawn in, or Avould fall together, so as to prevent the air from passing into the lungs ? The windpipe was made of the firm, unyielding cartilage, for the very purpose of keeping the passage for air to the lungs constantly open. Had it been made otherwise, life would be in danger every moment. How clearly we can trace in this, the thoughts of the Creator Avhen he designed and made the lungs. Fred.—I never before thought why the windpipe was made so hard. How kind it was of God to make 146 ANATOMY and physiology ___^________ Bronchial tubes and air-cells. it so that it could not close up when we drew in breath. Frank.—/never thought any thing about it. Mary.—Nor I, neither, but I shall, in the future, think much about it. Father.—Bronchial tubes. The windpipe divides into two branches, called bronchial tubes, one of which passes into the right, and one into the left lung; and these branches continue to divide, and subdivide into tubes, smaller and smaller, until they become invisible to the naked eye, each ending, as before stated, in a minute air-cell. Fig. 30. bronchial tubes and air-cells. Fig. 80. 1, a bronchial tube, divided into three branches; 2,2,2, air-cells; 3, branches of the pulmonary artery winding around the air-cells with the dark blood to be reddened. In the act of breathing, every time we inhale the air, or take in breath, these air-cells are filled with air, which is immediately exhaled, or thrown out of the lungs, and a fresh supply is again inhaled, and then exhaled, and thus the process of breathing goes on from the first to the last moment of life. Now can you tell me what benefit there is in con- rendered attractive. 147 Oxygen and nitrogen. stantly drawing air into the lungs, and throwing it out again, or, in other words, inconstantly breathing? Frank.—We could not live without breathing ! Father.—But why could we not live without breath- ing? Frank.—I do not know, Father, how it is, but I know that I should not live long, if I did not breathe. But how breathing keeps me ahve, I cannot tell. I wish you would explain it. Do we live upon air? Father.—Yes ; we live upon air, as much as we live upon food. And the demand for air is much more constant and urgent, than for food. We can live weeks without eating, but we cannot live minutes without breathing. Frank.—I know it is so, Father; but how can the lungs, drawing in, and blowing out air, like a great bellows, support life ? Father.—The lungs are one of the most important organs of the body, and there are no others, if Ave except the heart and brain, upon the function of which, life so immediately depends. Do you recollect that St. Paul, in Ins memorable speech to the Athenians on Mar's hill, says, " He giveth us life and breath, and all things !" Here, St. Paul speaks of breath as one of the peculiar gifts of God. I will now explain the manner in Avhich air, taken into the lungs, sustains life. The air we breathe, called atmospheric air, is com- 148 ANATOMY AND PHYSIOLOGY Uses of oxygen and nitrogen._____________________ posed of two gasses, called oxygen and nitrogen gas, in the proportions of about twenty-one parts oxygen, and seventy-nine nitrogen, with the addition of a small percentage of carbonic acid and vapor. Oxygen is the vital principle of the air, and supports all animal and vegetable life. The oxygen is taken up by the blood in the lungs, and conveyed through all parts of the body. Frank.—Father, how does the oxygen get into the blood? Father.—You recollect what I told you relative to the minute air-cells of the lungs,—that the inner sur- face of these cells, if spread out, would be thirty times greater than the surface of the body, or would be larger than the floor of a room, twenty-five feet square. Frank.—Yes, I recollect that, but what has that to do with the oxygen of the air getting into the blood ? Father.—It has a great deal to do with it, as I was about to explain. Oxygen has a greater affinity for, or is more dis- posed to unite Avith blood, than to remain united Avith nitrogen ; and as the blood passes through the minute blood-vessels of the air-cells, which are very thin membranes, the oxygen separates from the nitrogen, passes through this membrane, and is absorbed by the blood; and this large extent of surface of the lungs, or air-cells, is to bring and keep a large amount of air rendered attractive. 149 How breathing sustains life. in contact with the blood. The blood, you recollect, loses its bright vermilion color, while circulating in the capillaries, and in the veins it presents a dark purple color, or is nearly black. The cause of this dark color of the blood is as fol- low8 :—A poisonous agent, called carbonic acid, is formed in the system, and is taken up by the blood, while passing through the capillaries, and this renders the blood unfit for further use until the carbonic acid is, in some way removed; and this is accomplished in the following manner. The dark venous blood, containing the carbonic acid, is carried to the heart by the veins, and, by the action of the heart, is conveyed to the lungs; and the carbonic acid, having a greater affinity for, and being more disposed to unite with atmospheric air, than to remain with the blood, passes out through the sides of the air-cells and mingles with the air in the lungs, and is thrown off from them with the breath. These two important objects are accomplished by every breath of air taken into, and expelled from the lungs,^-the vital principle of the air—the oxygen, is absorbed, or taken up by the blood, and the poisonous carbonic acid is thrown off. And this process is going on during every moment of life, asleep or awake, —absorbing oxygen with every breath inhaled, and throwing off carbon Avith every breath exhaled. In this way, the dark colored, impure blood, is 150 ANATOMY AND PHYSIOLOGY Carbon, how generated. relieved of its impurities, and by absorbing the oxygen of the air, again assumes the bright scarlet color, and is endowed anew wTith the principle essential to life. Fred.—How wonderful are the ways and works of God ! But I AA'ish to ask, how much air is taken into the lungs at each breath, and how much oxygen is taken up by the blood ? Father.—A common sized man inhales about forty cubic, or solid inches of air, at each inspiration, and the blood absorbs tAvo cubic inches of oxygen, Avhich is thirty-six cubic inches a minute, or tAventy-one hundred and sixty per hour, or thirty cubic feet per day. Fred.—Does the blood absorb all the oxygen of the air taken into the lunjrs ? Father.—No, only about one-fourth of it is taken up by the blood at the first inspiration. But if we inhale the same air several successive times, addi- tional portions of the oxygen Avill be absorbed each time. Frank.—And how much carbonic acid is throAvn off? Father.—There is a less quantity of carbon exhaled, or thrown off, than oxygen inhaled, there being about twenty cubic inches per minute, or over sixteen cubic feet per day. Miry.—Father, how does the poisonous carbon get into the blood? rendered attractive. 151 The blood, how purified. Father.—It is generated or produced by the changes that take place during the process of nutrition. And had there not been some way provided by the Creator, by Avhich it could be throAvn off, it would cause death in a feAv moments. In proof of this, I need only cite the'fact, that if one ceases to breathe, or " holds the breath," for only a few seconds, the carbon retained in the blood, which should have been thrown off with the breath, causes the face to turn purple or black. I will now repeat, in a few words, that you may the better understand it, the substance of what I have said in regard to the blood. In the arteries, it is of a bright scarlet color, con- taining all the elements of nutrition obtained both from the food and from the air while passing through the lungs. While circulating through the capillaries, the nutriment is absorbed, or taken up by the tissues, or parts through Avhich it Aoavs, and at the same time, the blood is filled with carbonic acid,—a poisonous o-as which renders the blood unfit for further use until it is relieved of the carbon. It is then returned by the veins, to the heart and i mo-s, where the carbon is taken up by, or unites with, the air in the lungs, and is thrown off with the breath. fc And this process is going on during every moment of life. The blood is absorbing, with every breath, the vital principle from the air in the lungs, 152 ANATOMY AND PHYSIOLOGY Carbon, food for vegetables. and carrying it to, and depositing it, in every part of the body, giA'ing life and vigor to the system; and is also, with every breath, throwing off the poison, Avhich, if retained in the blood, would instantly cause death. We might in truth say, that Avith every breath we inhale life, and exhale death. And what kindness it was in our Maker, so to form the lungs, and all the parts concerned, that this vital process goes on Avithout a moment's cessation, by day and by night, without a thought, or a moment's care of ours. Fred.—Hoav stupid and thoughtless I am,—always to have been breathing, and never before to have known, or even to have thought, of the wonderful facts you have told us ! But I Avish to ask Avhat becomes of the carbon that is constantly thrown off by the lungs ? I should think the air Avould become poisonous in the course of time, and unfit for use. Father.—-It certainly would, had not God, in the arrangements of his works, appointed a beneficial use for Avhat otherwise would have been destructive in its effects. Carbon, that is poisonous to man and beast, is the food upon which vegetables live. It is the nutriment of trees and plants, as oxygen is of man and beast. And Avhile all vegetables absorb carbon, which is exhaled or thrown off by animals, they, in turn, exhale RENDERED ATTRACTIVE. 153 Oxygen, support of animal life oxygen for the support of animal life ; and thus the balance is preserved between the amount of oxygen required for man, and carbon for vegetables, and the air is thus kept in a condition to sustain both animal and vegetable life. There is another fact to which I wish to call your attention,—a fact, of which, perhaps, you have never thought. To sustain life, we must breathe every moment; but we need food but two or three times in twenty- four hours. Now think of the goodness manifested in providing for these Avants. The air, Avithout which Ave could scarcely live one minute, surrounds, envelops, and presses upon us, as the water does upon the fish in the ocean. We could not get away from it if avc Avould. It is ever present with us, and always ready for use. It surrounds the whole earth, and rises forty or fifty miles above its surface. But food, which Ave need to use but seldom, is pro- vided in small quantities, and we keep it laid by to be used when needed. Were a man obliged to travel where he could get no food, he could easily take with him a supply for two or three days. But if he were obliged to take a supply of air for two days, it would require more than sixty hogsheads—a rather cumber- some load. 154 ANATOMY AND PHYSIOLOGY. Moral reflection. Let us now close this social interview, impressed with the wonderful provision our heavenly Father has made for our physical, or bodily wants, and for the continuance of life, and the enjoyment of health. CONVEESATION XI. THE CIRCULATION OF THE BLOOD. The heart, a description of—The heart a d