INTRODUCTORY ESSAY 
ON THE 
HUMAN ORGANISM AND ITS FORCES. 
WITH 
REMARKS ON DR. LEHMANN'S DOCTRINE OF VITAL FORCES. 
BY 
SAMUEL JACKSON, M.D., 
PROFESSOR OF THE INSTITUTES OF MEDICINE IN THE UNIVERSITY OF PENNSYLVANIA. OF THE 
HUMAN ORGANISM. 
GENERAL RELATIONS. 
The organism of man, in its physiological, pathological, and 
therapeutical relations, is the subject and object of medical science. 
A comprehensive view of its general nature, and of its varied 
phenomena, will facilitate the investigations indispensable for a 
perfect understanding of them, by which alone medicine can be 
constituted a science. Without this knowledge, it cannot rank 
above an art or empiricism. 
Regarded in its completeness, it is an organic mechanism, the 
last and the most marvellous of the works of God; the fulfilment of 
the Creative thought in this world. In its structure, it is in the 
highest degree complicated ; in its nature, it is compound: it com- 
prehends within itself all organic nature. As in every mechanism, 
its phenomena are divisible into statical and dynamical. 
The first embraces its material structure and forms: the second, its 
varied movements and its forces, or causes of its actions. It includes 
three distinct natures, or spheres of existences-vegetable, animal, 
and spiritual, or psychological. They form three separate classes 
of phenomena, or branches of science; vegetability, animality, 
spirituality, or psychology. The first is characterized by growth, 
development, nutrition, and secretion: the second, by sensibility, 
general and special; contractility or irritability; spontaneous and 
voluntary movements and locomotion : the third, by consciousness, 
perception, ideality, causality, moral sentiments, and instincts. 
The actions belonging to the first, are vital, chemical, and physi- 
cal; to the second, mechanical, physical, and dynamical; to the last, 
psychological and metaphysical. 20 
OF THE HUMAN ORGANISM. 
The special or organic instruments of the first are germs, 
cells-epithelial, nWcousA and glandular - fibres, and the gan- 
glionic or sympathetic nervous system: of the second, muscular 
fibres, muscles, and the spinal nervous Vystem, and nervous organs 
of the special senses; of the third, the qerebral lobes, hemispheres, 
or brain. , k » 
The above phenomena blend together, are interdependent, closely 
associated; and are the most intricate that exist in nature. They 
can be understood only when subjected to an accurate analysis, by 
which each component of a complex phenomenon may be sepa- 
rately demonstrated. This indispensable process for the acquiring 
a reliable knowledge of organic phenomena, necessitates a compe- 
tent acquaintance with each science of which the elementary phe- 
nomena are subjects. 
A deficiency of this requisite has been, and continues to be, 
a source of error in observation, and of fallacy in interpretation. 
Properly to comprehend a complex phenomenon, it must be 
recognized as such; it must be viewed in each of its aspects, in 
each of its separate attributes; the action and influence of each 
component part must be appreciated in the production of the gene- 
ral result, the object of research. A partial view, however complete 
it may be; the determination of a single property, or of a single 
component, however accurate, cannot explain the attributes, actions, 
or nature of the compound. Errors of this kind have abounded in 
medicine. It is only within a few years that the means of correctly 
analyzing the phenomena of living beings was possible. 
The unstableness of all former theories and doctrines in medicine 
arose from this defect. They were based on a partial view, or on a 
single fact of life, mostly dynamical, as vital force, and irritability, 
or sensorial power; or on chemical views. Most of the organic 
chemists of the present day neglect all other components of a 
phenomenon except the chemical; and the inferences are conse- 
quently incorrect, although the chemical fact they establish may be 
of great value when taken in conjunction with others. The chemi- 
cal view presented of the blood in most works of organic chemistry, 
gives no adequate idea of that fluid as circulating in the vessels, 
and of its relations to vital phenomena. The pure physiologists 
who discard chemistry and physics as the leading characteristics of 
organic or vegetative functions, are nearly as remote from the truth 
as are the chemists. A just appreciation of the complex phenomena OF THE HUMAN ORGANISM. 
21 
of the human organism can be obtained in no other mode than by 
viewing and treating them by the lights of the collateral, physical, 
chemical, and other sciences, to which their elementary phenomena 
belong. 
The material substance, the basis of the structure of the organism, 
is plastic, or organizable matter. The elementary plastic matter is 
albumen, which becomes transformed into various proximate plas- 
mata, of which the different s^X elementary tissues and organs are 
formed. 
CHEMICAL RELATIONS. 
Organic matter has for its constituents the common chemical 
elements of inorganic bodies. Four of these, carbon, nitrogen, 
hydrogen, and oxygen, may be regarded as the special chemical 
elements of organic matter. They alone, of all the chemical ele- 
ments, possess the power of forming almost unlimited series of com- 
binations with each other, and those series again are endowed with 
similar powers of combination. 
This attribute adapts them to the purposes of organic nature: 
without it, organic matter and organic bodies could have no exist- 
ence. The chemical elements that constitute organic matter, are 
not divested of their special nature, properties, or relations, when 
they enter into its composition: they do not cease to be chemical 
substances any more than when they form inorganic compounds. 
The older physiologists were firmly convinced that chemical actions 
and vitality were essentially incompatible; and many physicians of 
the present day adhere to the same opinion. From the imperfection 
of chemistry, the chemical actions of living beings could not be 
recognized or understood, and were denied. So far are these 
opinions from the truth, that vital actions and organization are 
impossible without chemical action. Organic matter is not, like 
inorganic, an originally created, self-existing, and indestructible 
substance, as it was supposed to be by Bufibn. The vegetable 
kingdom is the great chemical laboratory of nature, in which are 
effected the decompositions of carbonic acid, water, and ammonia, 
in order to obtain the four essential chemical elements of organic 
matter, and to combine them along with sulphur, phosphorus, &c., 
into an infinite number of organic matters, vegetable and animal. 
These are the materials for the organization and development of the 22 
OF THE HUMAN ORGANISM. 
plants themselves, and animal organic substances, for the construc- 
tion of animals. The albuminoid organic substances, named by 
Liebig vegetable albumen, vegetable fibrin, and vegetable casein, 
are the primary or crude organic substances, elaborated by chemical 
action in vegetable cells, destined to the production of animal albu- 
men, fibrin, and casein, the crude organic plasmata, or substances 
from which are formed the immediate organizable or plasmatic 
matters of the different animal tissues. These last organic sub- 
stances are produced in The formative act of nutrition or assimila- 
tion, at the n^ment-the organic form;pl$he special animal structure 
•is generated. Thus, musculin, a chemical modification of albumen, 
does not exist in the blood. It is known only as forming the or- 
ganic material composing the solid portion of the muscular fibrillae: 
the transformation of the albumen must take place in the muscular 
fibrilla simultaneously with the production of its form. The or- 
"ganic matter of animal tissues is not permanent. From the great 
number of its chemical equivalents, or atoms, it is highly mutable. 
This character is most striking in some structures, as in mucous, 
glandular, muscular, and nervous tissues. The functional actions 
of organs cause waste and destruction of organic material propor- 
tioned to their activity. This is a result of chemical action, indis- 
solubly connected with vital action. In vegetables, the predominant 
chemical action consists in the deoxidation of organic substances, 
the oxygen being chiefly discharged into the atmosphere, while new 
organic substances are produced, as wax, oils, acids, &c., from 
the deoxidation of starch. Oxidation is the predominant chemical 
process in animals. The oxygen introduced into the blood by the 
function or act of respiration, combines with the carbon and 
hydrogen of the organic matters of the blood and the tissues. 
The whole chemical arrangement is broken up, and a reduction 
of the complex plastic substance into simpler bodies takes place, 
from successive processes of oxidation. They are creatin, creatinin, 
inosin, inosic acid, uric acid, urea, and, in addition, lactic, sulphuric, 
and phosphoric acids, and other unknown substances that lie con- 
cealed in the extractive matters enumerated by the chemists as 
existing in the blood and urine. 
Independent of these normal chemical actions, consisting in the 
molecular changes and transformations of the plastic organic 
matter, there are other chemical changes, some therapeutic, some 
abnormal or pathological, belonging to the relations of the plastic OF THE HUMAN ORGANISM. 
23 
or organizable substances with other bodies. Albumen, fibrin, and 
other proximate organic bodies, unite chemically with many of the 
chemical elements, as with additional quantities of oxygen, or with 
acids, metallic oxides, and earthy, alkaline, and metallic salts. 
Through this combination some of these substances are absorbed 
into the blood. Doubtless many other bodies possess chemical 
relations with the plastic organic substances of the blood and 
tissues, some entering into combination with them, others exciting 
molecular action and evolving new compounds, or transforming 
them into new matters, by causing new molecular arrangements 
and production of new organic matters. In this mode, abnormal 
contagious animal poisons are generated in the organism, when in- 
troduced into it by inoculation or otherwise. A minute quantity of 
smallpox matter inserted in the skin, or an invisible miasm of it 
inhaled from the atmosphere, acting as a kind of ferment, will give 
rise to the production of some ounces of an identical matter, in a 
case of confluent smallpox. The inoculation of a small quantity 
of putrid organic matter by a slight wound or scratch in dissection, 
will so destroy the crasis of the blood as to cause death. Absorption 
of sanious discharges from the uterus, it is probable, gives rise to 
some of the fatal forms of what is called puerperal fever. And 
again, the normal chemical changes attending the organic actions are 
accelerated by some bodies, as acetate and nitrate of potash, iodide 
of potassium, and the mercurial preparations. It is this that con- 
stitutes an alterative action. Those substances are organic altera- 
tives. Other substances retard those changes and diminish the 
waste of the tissues; such are alcoholic liquors, caffein, thein, and 
the narcotics. To a certain extent, it may be the action of some 
vegetable tonics. 
The whole history of organic matter, it is apparent, is essentially 
chemical. Itself a chemical product, it is incomprehensible in its 
infinite, endless forms, and incessant changes, without a knowledge 
of chemistry. It is the elaborated product of the chemical labora- 
tories of nature-vegetable organic cells. But the immediate plastic 
material of each tissue of an organized being, always a special 
organic material, is generated or assimilated from a crude plasma 
of the nutritive fluid, in the tissue itself, by the organizing or germ 
force of the tissue. The formation of organizable plastic matter, 
necessitates a living organism, independent of which it can have no 
existence. In this necessity, we have the scientific demonstration 24 
OF THE HUMAN ORGANISM. 
of a creation, and the direct primary agency of a Creator, the first 
cause of the organized world. 
Organic chemistry is identified with physiology and medicine. 
No absolute progress can be made by either without it. The 
future progress of both those departments must depend, to a great 
extent, on the development of its principles and higher perfection 
of its methods of investigation. The present work, principally a 
translation of Lehmann's Handbook of Physiological Chemistry, is 
believed to be the best adapted to initiate the student in a know- 
ledge of physiological or organic chemistry, indispensable to a 
scientific medical education. 
STATICAL RELATIONS. 
The animal is an organism, a complicated living mechanism. In 
carrying on its numerous and diversified operations, it presents a 
great variety of phenomena, and possesses numerous subordinate 
instruments, each appropriated to a special office. They are termed 
organs and apparatuses of organs. Each organ and apparatus 
possesses a special organization, is endowed with a special vital 
activity and properties, performs a special function, and manifests 
special phenomena. To be thoroughly known, they must be sub- 
jected to exact analysis, be investigated by experiment, as are 
inorganic bodies, and be assigned to the natural class to which their 
actions and phenomena show them to belong. A chemical, physical, 
mechanical or dynamic fact does not lose its proper nature and 
attributes, or cease to be subject to its proper laws, because it 
occurs in a living organism, and is associated with special vital 
facts or phenomena, or controlled and directed by vital force. 
In the living organism of man are found to concentre all the 
actions and phenomena, chemical, physical, and mechanical, that 
exist in the exterior inorganic world, combined with those peculiar 
to organized or living beings. This may be expressed in the formula: 
inorganic phenomena, plus organic and psychical phenomena. 
The chemistry, physics, and mechanics of the human organism 
are transcendental; they are each the development of the highest 
possible conception in each branch of knowledge; the instruments 
that execute them are inimitable by any of man's invention, for the 
purpose of exemplifying the phenomena and principles of the 
natural sciences. Such, for example, is the eye as an optical instru- OF THE HUMAN ORGANISM. 
25 
ment, the ear as an acoustic instrument, the larynx as a phonetic 
and musical instrument, the vascular system as a hydrostatic appa- 
ratus, and the muscular system as a mechanical mechanism. 
The organism of man in action is a locomotive engine, in the 
perfection of its machinery and adaptation to its purposes, infinitely 
beyond any similar engine that man ever can devise. It is com- 
posed of a number of distinct mechanisms, or machines and instru- 
ments, by which it is self-formative; by which it procures and 
prepares the materials for its repair and renovation, conveys them 
to every part of its structure where they are required, generates its 
own temperature and the forces that work its machinery, and brings 
its mechanical powers into action. 
The intelligence for whose use this engine exists, whose will it 
obeys, whose work it performs, that rules and controls it for the 
purpose of accomplishing the objects of life, resides in and is a com- 
ponent part of the machine itself. The intellect is to the human 
locomotive, what the engineer is to the steam locomotive. It em- 
ploys the extraordinary powers of this wonderful and magnificent 
mechanism to mould exterior material nature, after the ideal crea- 
tions of its own interior and spiritual nature, evolved in ideas and 
thought. The state of society of any country, its institutions, its 
works, its science, its arts, the meliorating features impressed on 
the rude face of nature by its industry and labors, are the reflec- 
tion and manifestation of the intelligence, knowledge, and moral 
character of its people. 
By his locomotive machinery, aided by his inventions, that ren- 
der it more efficient, that augment his powers, man overcomes all 
the barriers and obstacles of nature. No mountain is so lofty as 
to be inaccessible to his footsteps, no valley into whose depths he 
cannot penetrate; he mounts into the upper regions of the air to 
gratify his curiosity; he perforates the earth and descends into its 
bowels thousands of feet below its surface, to bring forth its buried 
treasures; the wide expanse of ocean he has made his highway; 
and he circumnavigates the earth in the pursuit of pleasure, science, 
or wealth. These extraordinary powers he owes to his inventive 
faculties and the knowledge acquired by his intelligence. With 
their aid he devises the required means that enable him to seize 
on the forces and appliances of nature, to turn them to his purposes, 
and, through their agency, to triumph over nature herself. 
The amount of mechanical force and power, produced, and 26 
OF THE HUMAN ORGANISM. 
expended in the daily working of the animal machinery, is far 
beyond what can be conceived by those who have not investigated 
this subject. I will here merely state that, for the organic functions 
of respiration and circulation, the daily amount expended is not less 
than some thousands of pounds; and a considerable sum is required 
for the daily operations of the ingestion and digestion of food and 
expulsion of the excretions; while the aggregate result during labor 
and locomotion of various kinds, is often enormous, exceeding 
frequently, two millions of pounds a day. The immediate mechanic 
force by which the mechanic power of the muscular system is 
brought into action, is generated in the spinal system, the anterior 
nervous ganglia of the spinal cord or axis, and appears to be either 
derived from a transmutation of heat into the nervous motor or 
excitor force; or that force and heat are correlative. A direct 
relation certainly exists between the two. MM. Jules, Serres, and 
other physicists, have demonstrated the identity of heat and me- 
chanic force: they are mutually correlative and equivalent to each 
other. This fact is expressed by M. Jules in the following for- 
mula :- 
One degree of heat is equivalent to 750 pound-feet. Or, 
One degree of heat is the equivalent of a mechanic force that will 
raise 750 pounds one foot. 
The same principle is equally true and applicable to animal me- 
chanics. 
In the animal mechanism, the heat, the equivalent of its mechanic 
nervous force, is evolved by the oxidation or slow combustion, 
chiefly of carbon and hydrogen, in the blood. The oxygen is 
introduced into the blood by the process of respiration, and the 
hydro-carbons and carbo-hydrates, by the food-as oils, sugar, 
starch, &c., digested and prepared by the functions of the alimentary 
canal, so as to be absorbed, and introduced into the circulatory 
apparatus. The amount of pure carbon that must be introduced 
into the blood, by the food, and oxidized, to furnish the heat cor- 
relative of the nervous mechanic force each day, in labor, is not 
less than from 10 to 12 ounces. In this exhibition of facts is de- 
monstrated the close, immediate connection between different func- 
tions and actions, as respiration, digestion, absorption, circulation, 
oxidation, animal heat, nervous force, and mechanical actions. The 
working power of man is a product of the food on his dish; it comes OF THE HUMAN ORGANISM. 
27 
from his meals: and so also is it with his blood, and flesh, his 
limbs, organs, and viscera. They are constructed of the nitrogen- 
ized organic matters of food digested in the stomach, absorbed and 
assimilated. 
Food or aliment is the commencement of organization; it may be 
said, of life; for the first vital action of the germ is to absorb and 
assimilate nutritive matter, for the augmentation of germ material, 
and the formation of the germ mass, the first stage in the develop- 
ment of the organism; and the whole of organic or nutritive life 
is the repetition of its first commencing act. 
FORCES, OR DYNAMICAL RELATIONS. 
This word dynamics is derived from the Greek power, 
force, rule. It was confined for a long period to the science of 
mechanics, to designate the laws and actions of mechanical machines 
and movements of bodies. 
It has acquired, with the progress of science, a much more extended 
application. It is now the equivalent or synonym of forces, and is 
employed to express the science of acting and moving causes, not 
only of solids or mechanical bodies, but of all actions and move- 
ments whose cause is unknown. In this sense it is introduced into 
medicine; and in physiology, is applied to designate the forces of 
the living organism, or causes of its actions; and in therapeutics, 
is used by some to express the causes of medical action as dis- 
tinct from the medical substance itself. In the mechanics of the 
muscular system, the term is of as legitimate application as in 
common mechanics. The spinal nervous apparatus is a dynamical 
system, generating forces that excite and control muscular actions, 
that perform the mechanical functions of the economy. 
The direct meaning of the word force, synonymous with dyna- 
mics, derived from the Latin fortis, is strength, power, energy. 
It is used for want of a more fitting word in science to express 
an abstract idea, a result of a mental process of reasoning. The 
common experience of our senses teaches us that inorganic bodies, 
at rest, never move unless set in motion by an impulse derived 
from some other body, agent, or matter. It does not move of 
itself. Whatever produces the motion, is regarded as the cause 
of the motion, and the mind infers it exerts an action indicating a 
force as the cause of the motion or action. 28 
OF THE HUMAN ORGANISM. 
But movements and actions are observed to occur often without 
any known tangible or perceptible cause of the movement or ac- 
tion. Of this unknown cause of action and movements, the mind 
forms an abstract idea by a process of reasoning, as a force or 
unknown cause, producing actions, movements, or, in other words, 
phenomena. Phenomena, actions or movements, of the same na- 
tures and characters, are constantly reproduced under the same 
conditions. The mind infers from this circumstance the existence 
of constant, persistent, and special forces. The term force has no 
other meaning-expresses no more than an unknown cause for 
known or observable phenomena. 
Phenomena, recognizable by our senses, and comprehensible by 
the intellectual faculties, are numerous, various, and different. From 
their resemblances, coincidences, and differences, always permanent 
and consistent, they are capable of being arranged into divisions, 
classes, orders, genera, &c.: that is, the mind arranges and classifies 
phenomena according to the above circumstances of agreements and 
dissimilarities which are observed to exist in nature. 
The forces to whose action the special phenomena observed in 
nature are to be attributed, are divisible into two classes: the 
physical or general, and the organic or vital forces. The first are 
classed and named by physicists, as gravity, light, electricity, mag- 
netism, and chemical affinity. These terms in reality express no 
more than constant modes of actions, or phenomena: characterized 
by Mr. Grove as " affections of matter." They are the only forces 
recognized by physicists. To- which, it appears to me, are to be 
added the second class, or vital forces. They are, 1st, organic, or 
formative force ; 2d, the spinal nervous excitor, and motor forces ; 
and 3d, muscular contractility, or irritability. 
Before proceeding further in this discussion, it will be necessary 
to make a short digression for the better understanding of this 
subject. 
It is a remarkable feature of intellectual operations, that from 
the earliest period of knowledge, of science, and philosophy, down 
to our day, two distinct modes of viewing this subject, two oppo- 
sides of this question have occupied, and been presented by, 
-i-ffimking and observing minds. The ideas arising from these 
views have lain, and yet lie, at the root of scientific principles 
and philosophic thought, forming two antagonist schools. They 
generally date from two of the eminent intellects of Grecian OF THE HUMAN ORGANISM. 
29 
origin, Pythagoras, born 584 B. C., and Thales, 640 B. C. The 
first taught that matter was incapable of any action or movements 
from its innate powers. God was the power whence all natural 
phenomena proceeded through subordinate agents. This is the 
origin of the spiritual philosophy and the modern dynamic theories. 
The abuses and perversions of this doctrine by the ignorant, and 
those incapable of enlightened and broad intellectual views, have 
produced ontology in science, and superstition in religion. 
Thales, on the other side, regarded matter as possessed of inherent 
or innate forces and properties, from which all natural phenomena, 
and all objects, animate and inanimate, have proceeded, and con- 
tinue to be produced. This is the material school, and, pushed to 
its extreme results, leads to atheism. 
In our time, the first of these primary conflicting opinions is 
represented by the doctrine that matter is devoid of active forces, 
and that phenomena are dependent on imponderable forces acting 
on ponderable matter, changing, modifying its states, conditions, and 
forces; and are the sole causes of action or phenomena. 
The second is embodied in the doctrine that matter is endowed 
with active forces as properties, by and through which, all the phe- 
nomena of nature, its forms, actions, motions, molecular or in masses, 
are accomplished. This doctrine escapes from the inevitable con- 
clusion to which it leads-atheism-in attributing, as is done by 
some, the possession of these properties by matter, as endowments 
conferred on it by the Supreme Creator. 
Modern researches have shown that the forces of nature, pre- 
viously enumerated, are correlative, cannot exist independent of, 
and are convertible into, each other. 
The conclusion from the above facts and views, is that what are 
termed natural or physical forces, are no more than modes of mani- 
festation of one force, one agent. In 1836-7, I advanced this 
opinion, and, in addition, that the phenomena of living beings were to 
so great an extent identical with the ordinary phenomena of physics, 
that " Physiology might very properly be designated as organic 
physics." In 1843, Mayer, of Ileilbron, promulgated the same 
opinion. But it was Mr. Grove, of London, who first, in a complete 
treatise, undertook to prove the truth of this proposition. In a 2d 
edition, 1850, he throws out the conjecture that the doctrine of 
correlation will apply in physiology; and cites muscular action and 
animal heat as probable instances. This very application of the 30 
OF THE HUMAN ORGANISM. 
doctrine I had made the year previous, 1849, to animal mechanic 
force as correlative of heat, in a paper read at the meeting of the 
American Medical Association, held in Boston. 
This doctrine was announced by me as early as 1837, in a pub- 
lished lecture. This proposition was then laid down, " that the 
same causes and actions which in inorganic bodies constitute 
physics, in organic bodies constitute physiology, or, as it may be 
more aptly termed, organic physics." 
The idea then broached, subsequently ripened into a complete 
development; and my lectures were arranged on a plan in con- 
formity to it. 
Dr. Carpenter, in the preface to the third edition of his General 
and Comparative Physiology, claims " as more particularly his own," 
the doctrine of the " mutual connection of the vital forces and their 
relation to the physical." I indulge the hope that this statement of 
similar views promulgated by myself eighteen years since, annually 
repeated and so extended as to form a full section of my course, 
will not be considered out of place on this occasion, or subject me 
to the imputation of egotism. 
The doctrine of the correlation of the physical forces has been 
generally adopted; and consequently, if a clear insight has been 
obtained of the nature of any one or more of them, that of all the 
others must be similar or identical. AV hatever theory is adopted 
to explain the phenomena of one must be applicable to the others. 
Now, as respects two of the forces, light and heat, physicists have, 
without an exception at this time, embraced the dynamical or 
undulation hypothesis. According to this doctrine, the phenomena 
of light and heat are due to motion or undulatory vibrations excited 
in an aerial fluid existing throughout the universe, occupying the 
interplanetary spaces, and penetrating and existing in the interstices, 
and surrounding the molecules of the densest bodies, whether 
inorganic or organic. This fluid is named the Ether. It is 
mentioned by Aristotle; Newton advocated the hypothesis, and 
employed it in solving some of his philosophical problems; he 
estimated its specific gravity as 750 times less than the difference 
between the atmosphere and granite rock. Euler assumed that the 
ether is 36,000,000 times thinner, and 1,278 times more elastic than 
atmospheric air. 
The grounds of this hypothesis are by no means vague. It is 
clear, without any doubt, that in vision or seeing there must exist OF THE HUMAN ORGANISM. 
31 
some agent or body between the retina of the eye, the nervous 
sensitive tissue or membrane, and the exterior visual object. The 
retinal membrane is the portion of the eye that receives the direct 
impressions proceeding from the external body. In this* impres- 
sion, in reality, consist light and color. It is not a single 
and simple membrane, but a complex one; it is composed of 
thousands of minute, independent and distinct sensitive spaces, or, 
as they may be regarded, associated retinas. Each one of these 
receives a separate, distinct impression, coming from each separate 
distinct point of the exterior body seen, a perfect miniature mosaic 
picture of which is thus represented on the retina, or is, it may 
be said, pricked into it by the rays of light; or, more properly, the 
undulations of the molecules of the ether. 
This body, this agent intermediate between external bodies and 
the retina, exists in the interior of the eye, diffused through all its 
tissues and interior media. It is the sole normal or physiological 
excitor of the special nervous sensibility of the retina, and the 
nervous central optical organs, provided in the order of nature, that 
animals may possess the function of vision. This is effected by the 
immediate relation this agent possesses with the nervous sensibility 
of the retina of the optic nerve and the optic lobes. The two must 
be closely related, and analogous or identical in their nature or 
innate constitutions. 
This accumulation of scientific probabilities almost amounts to a 
demonstration that a body or most tenuous fluid is present between 
all external bodies and the retina in the eye of animals. It is not 
the atmosphere, for it cannot penetrate the cornea, the lens, or the 
humors of the eye. Its presence would be injurious to vision by 
disturbing the course of the rays of light. 
Vision is not limited to the surface of our globe; it extends to the 
infinitely remote regions of space, and consequently the ether, whose 
systems of undulations or waves traverse those immeasurable dis- 
tances, and, impinging on the retina, cause light, or vision, must fill 
all space. 
The present philosophical hypothesis of physical or natural 
forces, presented in the preceding summary, in the present state of 
our knowledge must be accepted as the truest exposition of the 
causes of natural phenomena. Having it before us, we are better 
prepared to examine the relation in which they stand to the forces 32 
OF THE HUMAN ORGANISM. 
that, in the living organism of man, are the causes of its special 
actions and phenomena. 
These forces are manifested in the organic actions of which they 
are the causes, and must be studied and interpreted through them. 
In this manner alone can their identity or diversity, their correla- 
tion or irrelevancy with the physical forces be correctly appreciated 
and determined. 
ORGANIC FORCES. 
The only forces and phenomena that can properly be named 
organic or vital, are such as are exclusively found in organized and 
living beings. Two series of phenomena alone possess this charac- 
ter. They are, for the first series, the production of a formless 
plastic matter, and the development of typical organic forms-tis- 
sues, organs, organisms-from this formless material, and their 
maintenance by growth and nutrition. For the second series, they 
are the nervous excito-motor forces, and muscular contractility. 
Sensibility and intelligence, or the psychological actions, are nervous 
phenomena, to which the term force, and the actions oi force, are 
not applicable. 
The first series is common to all organic, or living beings-vege- 
table and animal: the last exists exclusively in animals. 
As the causes of the .above pheno ntena present special characters 
that distinguish them as mu^h from the physical forces as they are 
themselves distinguished from each other, I can perceive no valid 
reason why they should not be placed in a separate class, named 
organic forces, as they are most clearly the antecedents, or causes 
of especial organic phenomena, or actions. Guided by the light 
of our present philosophy, the organic or vital forces are regarded 
by many physiologists, among them Dr. Lehmann, the author of 
this work, as correlative of the common forces of the inorganic 
world. 
I now proceed to an investigation of the phenomena character- 
istic and distinctive from all others, that are specially organic, that 
are exclusive to living beings and to animal life. The first is- - 
ORGANIC, FORMATIVE, OR VITAL FORCE. 
This force presides over all organic beings-vegetable and animal. 
No organic form or action, or any phenomena of life, can have OF THE HUMAN ORGANISM. 
33 
existence in its absence. It is as perfect in the lowest and simplest 
as in the most complex and elevated of organic beings; in the 
monad as in man; in the cell vegetable as the oak; in the lowest 
form of tissues as in the most complex and developed. 
Organic force is the first cause of organic forms. Modality, or 
the production of organic forms from a formless, plastic fluid, or 
organic matter, is its distinctive characteristic. It is embodied in 
the germ. No living, no organic form, endowed with vital activity, 
ever had existence, or can exist, independent of germs. Every 
organic form is the realization, in an appropriate and special or- 
ganic material, of an Neal model, or type, of that form. 
This force is not self-acting. It is dormant like electricity, caloric, 
light, until excited into action. A definite temperature is an indis- 
pensable condition. In warm-blooded animals, 100° F. to 102° F. 
in the blood, is the normal temperature. Below this, say 96° to 97° 
F., germ development is imperfect, and arrested in its first stage. 
ORGANIC, OR VITAL ACTION. 
The result of the activity of organic force, excited by caloric, or 
heat, is the production of an organic action, life or formative action, 
summed up in the term nutrition. The nature and constituent 
factors of this action are now to be analyzed. 
It is a compound action, composed, 1st, of the production of an 
immediate, or special plastic organic matter, from a crude or proto- 
plasm ; 2d, of the creation, or production of special organic forms 
from the organic plastic matter ; 3d, of the death, or chemical dis- 
integration of the organized substance of the interior structures, 
and its transformation into simpler and lower combinations, form- 
ing the matters and substances of the excretions ; 4th, the moulting, 
desquamation, or casting off the dead and recremental material of 
the organic structure of the internal and external surfaces, in com- 
munication with the exterior world. At the same time, new or- 
ganic forms, and organized structure are being produced. 
The organic plastic matter is special for each tissue-musculin is 
the material for ^.uscular tissues, neurin for nerve tissue, the vari- 
ous gelatiniform^materials for areolar, serous, fibrous tissues, &c. 
Organic forms are equally various. Each tissue and each organ 
has its speciality of form, and arrangement of its component parts. 
These component parts, each having a special plasm and a distinct 
organization, are interwoven with the utmost intricacy, necessitating 34 
OF THE HUMAN ORGANISM. 
different and complicated chemical and constructive processes simul- 
taneously occurring in the same place and same moment of time, 
which are utterly inexplicable and impossible as the operations of 
the physical forces. 
The organic form produced is maintained amidst the incessapt 
decomposition of the organic substance in which the type of form is 
expressed. This is the most significant and characteristic fact of 
the organic or life action. It individualizes and separates it from 
every other kind of action. All inorganic forms are maintained 
by the absolute repose, or equilibrium of molecular actions. The 
form is destroyed utterly, when molecular actions are excited. 
Incessant molecular activity, and persistence of form, are the 
essentialities of organic, or life action. The cessation of the special 
molecular activity of living structure, is productive of the cessation 
of organic, or life action: it is death. The organic force disap- 
pears ; chemical affinity, that was forced by it to effect special com- 
binations of chemical elements, to form special plasmata, is now 
set free, to exert its natural tendencies, and the result is putrefac- 
tion, if the temperature be such as to excite it into a certain degree 
of activity. 
An organic action analyzed, reduced to its component phenomena, 
presents evidences of the combination of the following series of 
actions and phenomena:- 
1. Organic, or formative force, producing, creating it may be said, 
organic forms, or manifesting modality, stamping the form after an 
ideal type of tissue, or organ. 2. Chemical affinity, chained, con- 
trolled, and forced into the formation of special chemical combina- 
tions and formation of plasmata. 3. Chemical disintegration, retro- 
grade chemical products to be eliminated, or the dead organic 
material desquamated, and thrown off from exterior surfaces. 
This scries and union of forces and actions, entering into an or- 
ganic, or life action, can occur and exist only under absolute special 
conditions. These are, 1st, the presence of organic force embodied 
in a germ; 2d, a crude organic plasm; albumen in animals of the 
higher classes, capable of transformation into special plasmata; 3d, 
a definite temperature of 100° to 102° F.; 4th, oxygen, to effect, by its 
direct action, the chemical decompositions of the organized mate- 
rials wasted in the organic actions, and indirectly accomplishing 
the same result by the thousand acts of oxidation occurring in the 
organism, generating its temperature, and maintaining the endless OF THE HUMAN ORGANISM. 
35 
chemical actions required for the production of the secretions, ex- 
cretions, and numerous other products of the economy. 
The preservation of the above conditions of organic, or life actions, 
is the object of dietetics and regimen, or art of preserving health; 
and the investigation, of those conditions, in all their varied rela- 
tions, constitutes the science of hygiene. Their restoration, when 
in an imperfect state, or in any mode disordered so as to con- 
stitute disease, is the object of therapeutics and the practice of 
medicine. 
NERVOUS, OR MECHANIC FORCE. 
This force is wholly dissimilar, in every respect, to organic force. 
The character and object of this force, is to work the machinery of the 
organism so as to bring into operation the mechanical power of the 
organism required for various objects indispensable to its existence, 
to maintain the conditions of the organic actions, and for the pur- 
poses of animal existence in the creation. Its most perfect mani- 
festations are in animals of the higher classes. 
This nerve force is generated in the spinal cord, or axis, and the 
cerebral axis, medulla oblongata, crura cerebri, thalami, and corpora 
striata. These organs constitute the dynamic, or force generating 
apparatus. Mechanic nerve force is to the animal organism what 
steam is to the locomotive. The dynamic apparatus, or cerebro- 
spinal axis, is in the organism what the boiler is in the steam 
engine. 
This statement exhibits, in strong relief, the difference between 
organic and nervous force. The first exhibits no mechanic power 
in the organism, produces no direct mechanic effect. It is limited 
to the molecular actions required for the production of plastic matter 
and organic forms. 
The spinal nerve force is exclusively manifested in the mechanical 
movements of masses, as of the circulation of the blood, the expan- 
sion of the chest in respiration, in movements of the limbs and body 
in locomotion, and in the production of other mechanical effects. 
Notwithstanding these wide and strongly marked differences 
between them, the two have been, and continue to be, confounded 
together as one-as identical. This error, regarding nerve force as 
an Organizing force, as the cause of all organic phenomena, was 
committed by Oken, by Carus, by Klencke, by Unger, by Lamarck, 
Legallois, and Dutrochet, and is yet entertained by many French 36 
OF THE HUMAN ORGANISM. 
and German physiologists. It is advocated by a distinguished 
teacher in this city, who bases many of his pathological views on 
this hypothesis. This error arises from not analyzing the complex 
phenomenon of an organic action, and of not studying it in its first 
inception in the formation of germ matter, and development of the 
multiplication of the germ into the embryonic germ mass, the first 
stage of the animal organization; and further, the ignoring of the 
process of development in the seeds of plants, and of their organ- 
ization. To find the truth, it is not to be sought in complicated 
phenomena, but in the simplest, in which its expression is clear and 
distinct. 
Nerve force has been shown to be limited to an apparatus. 
Actions or phenomena requiring an organ or apparatus are, and 
must be, functional. Nerve force is, consequently, a function or 
office of the organs and apparatus on which it depends-the spinal 
dynamic apparatus. The apparatus itself is constructed by the 
formative organic actions directed and maintained by organic or 
vital force. 
Spinal nerve force is restricted to two series of phenomena-ex- 
citation of muscular mechanical actions and of general sensibility. 
Organic or vital force is universal in the organism; it requires no 
apparatus. It is present in every act of life, in every tissue, in the 
simplest as in the most complex: it is active in every living 
organic molecule. 
Spinal nerve force is composed of two distinct forces-an excitor 
force and a motor force. Each has a separate nervous apparatus or 
combination of organs for its manifestation. 
Excitor Nerve Force. 
The first, or excitor force, has a close affinity with sensibility; they 
are constantly confounded. It is an excitor of general sensibility, 
as well as of motor force. It is somewhat difficult to distinguish 
between them. Sensibility may, possibly, be no more than the 
mental perception and consciousness of the excited state of the 
excitor force, or of the afferent nerves. The excitor force, like 
special sensibility, is in contact with the exterior world. Impres- 
sions on the skin or mucous membranes excite it into action, as cold 
air, or water sprinkled on the face, recalling respiration in fainting, 
and worms or indigestible food in the alimentary canal, causing 
convulsions or spasms. OF THE HUMAN ORGANISM. 
37 
Certain irritations and impressions also of which we have no 
consciousness, excite its action normally, as in respiration, main- 
tained by the unconscious presence of carbonic acid or black blood 
in the lungs, and abnormally by splinters lodged in fascias, causing 
no sensation, yet producing tetanus after the wound has healed. 
It is independent of the brain or cerebrum. This is shown in 
complete palsy of sensation and motion, caused by injuries to the 
spine. The lower extremities will be drawn up violently, from 
tickling the soles of the feet, though the patient is unconscious either 
of the sensation or the movement of the limb. 
The apparatus of the excitor force are the posterior ganglia of the 
spinal marrow or axis, of the medulla oblongata, and nerves commu- 
nicating between those nerve centres and exterior and interior sur- 
faces. These nerves have ganglia on their roots, which is a distin- 
guishing character, though their office yet remains unknown. All 
impressions on, or states or conditions of surfaces are transmitted 
to the excitor ganglia or the posterior nerve centres of the spinal 
cord and medulla oblongata. 
Motor Force. 
The second or especial relation of motor force is with muscular 
contractility, and its function is to excite muscular contractions 
from which result mechanical effects. 
The apparatus to which it belongs, and through which it acts, are 
the anterior ganglia or nerve centres of the spinal marrow or axis 
and medulla oblongata, and the nerves that place them in connection 
with the muscular system. These nerves have no ganglia at their 
roots. This force is the direct physiological excitor of muscular 
contractility; and, in the normal state, is the only proximate cause 
of muscular action. 
Excitor and motor force are, in the organism, constantly asso- 
ciated in action. The continuous play of the respiratory muscles, 
of the heart, of the muscular coats of the stomach and intestines, 
is maintained in this manner. They are involuntary machine or 
automatic actions. The two forces are not identical, and often act 
independent of each other. Irritation, or any excited state of excitor 
nerves and surfaces, will cause pain without producing muscular 
actions or influencing motor force, as in some pure neuralgias. Sen- 
sations and muscular actions sometimes occur simultaneously, are 38 
OF THE HUMAN ORGANISM. 
connected, but more frequently sensations are unattended with 
muscular actions. 
The nervous force exhibits in some of the inferior animals 
remarkable varieties of susceptibility to the impressions of external 
bodies. The Batrachians, when placed in water of the temperature 
of 100° to 110° F., are immediately thrown into a state of spasmodic 
rigidity; a tetanic state is developed, which in a short time would 
prove fatal. If in this state they are thrown into water of the 
ordinary temperature of spring water, 45° to 48° F., the spasm 
immediately ceases, and they resume their usual activity. In the 
Ophiura, or Luidia, a species of the starfish, the very reverse of 
what occurs in the frog is observed. If taken from sea water, and 
plunged into fresh water of the same temperature, they die instantly 
in a state of the strongest tetanic extension and rigidity. 
Motor force, associated with and excited by excitor force, pro- 
duces what are called reflex actions. This name, though generally 
employed, is objectionable, as it involves a hypothesis which has 
not been verified. Excito-motor actions and automatic actions 
are preferable, as they indicate positive phenomena. 
Motor force is also excited into action by other causes, the whole 
forming four classes of actions. 
The first is the excito-motor or automatic actions as above de- 
scribed, constituting involuntary actions. 
The second are the excitements of the motor force by the emo- 
tions, constituting emotional actions. 
The third are the excitements of the motor force by acts of the 
mind, attended with a consciousness of the mental action, and are 
called voluntary actions. By these actions is carried out some 
determination, or is accomplished some desire or purpose, or is 
fulfilled some idea. 
The fourth is a new class, unknown to metaphysicians, but 
recognized by physiologists. Motor muscular force is often ex- 
cited by a fixed, strongly impressed and vivid idea, without that 
active participation of the consciousness that is called volition. 
Hence the individual is unaware of the cause of the muscular 
action, and in some instances is unconscious of its occurrence. 
The nervous excito-motor or mechanic force is not constant; it 
varies incessantly. The apparatus generating it is exhausted by 
prolonged muscular exertions. This state is expressed by a sense 
of weariness, lassitude, or fatigue, according to the degree of ex- OF THE HUMAN ORGANISM. 
39 
haustion induced. It is renovated by repose, from which proceed 
feelings of vigor and activity. 
The following are the conditions indispensable to its generation 
and normal action :- 
1. Gray neurine vesicles grouped into centres or species of ganglia 
in the posterior and anterior cornua of the spinal axis and in the 
medulla oblongata. 
2. Nerves communicating between interior and exterior surfaces 
and the posterior ganglia of the spinal axis-afferent or excitor 
nerves; and nerves communicating between the anterior ganglia 
of the spinal axis and muscles-efferent or motor nerves. 
3. Red blood corpuscles, in the proportion of 130 to 140 to 1000 
of dry blood, or 510 to 520 of liquid blood. 
4. A temperature of 100° F. in the blood. 
The identity of electricity and nervous force is a favorite suppo- 
sition with many writers at this time. The facts relied on are far 
from being positive. Those of Matteucci and Du Bois Raymond 
possess the largest amount of probability, but are not absolutely 
demonstrative. 
Molecular action is always attended with electrical phenomena. 
This kind of action is a constant characteristic of vital activity: 
and in those tissues and organs in which molecular action is ener- 
getic, electric phenomena are the most clearly manifested. Every 
living organism, as a whole, and in its several structures, is an 
electro-genetic apparatus. 
During life, the muscles, and the mucous membranes and skin, 
exhibit, with the galvanoscope, the most marked and highest evi- 
dences of free electricity. The nervous structure fails to affect this 
instrument in a decided manner, though the more delicate sensitive- 
ness of " the prepared frog's leg" proves its existence. This fact 
tends rather to show a less degree of electrical development in nerve 
structure, corresponding with slower molecular changes of organic 
substance, than in muscles and mucous membranes. 
Du Bois Raymond has demonstrated, by the peculiar apparatus 
he has constructed, and by his manipulations, that dead nerve struc- 
ture exhibits a feeble electric current. This can scarcely be con- 
strued as an evidence that the nerve force of the living apparatus 
is electricity. There is also a source of fallacy in the experiment 
that has not been noticed. Spallanzani had observed the fact that 
organized structure, when dead, until putrefaction has commenced, 40 
OF THE HUMAN ORGANISM. 
continues to exhibit the constant phenomena of living structures, the 
absorption of oxygen and elimination of carbonic acid. Robin and 
Verdeil assert that they have verified the correctness of this obser- 
vation. This chemical action must of course generate electric 
currents. 
Although the proofs of the identity of nervous force and elec- 
tricity remain as yet inconclusive, there is every reason to regard 
as probable a correlation between them; and that nervous force 
belongs to the same class; that it is, in fact, a special modification 
of the physical forces manifested in living organisms, and adapted 
to the special class of mechanical actions in them. It is ether 
transformed into nerve force, or this last is itself a modification of 
ether. REMARKS 
ON 
DR. LEHMANN'S DOCTRINE OF VITAL FORCES. 
BY 
S. JACKSON, M. D., 
PROFESSOR OF THE INSTITUTES OF MEDICINE IN THE UNIVERSITY OF PENNSYLVANIA. 
The foregoing views respecting the forces of the organism are at 
variance with the doctrine of the author of this work, Dr. Leh- 
mann. They are the opinions I formed early in my professional 
studies, and have been since entertained by me. The conviction 
of their general truth has strengthened with time and increased 
knowledge. The facts and arguments of Dr. Lehmann have been 
carefully considered and weighed, but have failed to convince me 
of their correctness, or to weaken confidence in my previous con- 
clusions. 
It is a fault not unfrequent with those absorbed in the pursuit of 
the positive sciences, and accustomed to find the objects of their 
researches subject to the application of fixed laws, and their diffi- 
culties solved by experimental demonstration, to expect that simi- 
lar means and processes are available and applicable to all other 
sciences. Habituated to reach certain results in the investigations 
of their limited range of phenomena, they demand the same con- 
ditions in those infinitely more complicated and widely different. 
The confidence with which they are inspired, leads them to assume 
that man's intellect is the measure of the universe, and that no truth 
can have a depth outreaching its capacity, or is placed beyond the 
grasp of its logic and comprehension. The unknowable is not 
acknowledged, and any hypothesis is preferred to a concession of a 
mystery. 42 
REMARKS ON 
Yet, a moment's reflection must show, that the causes of the laws 
whose unerring certainty they boast, are unknown, are mysteries, 
and must forever remain as such. It is the error of Dr. Lehmann, 
and it is common to most physicists, more particularly chemists, 
that he views the complex phenomena of life in one aspect-in 
their chemical relations. The physiological, or especial organic 
phenomena, are entirely neglected or overruled, though the settle- 
ment of the question in discussion must depend almost exclusively 
on a thorough investigation, not of the mere organic substance and 
its nature, but of the sole material fact to be determined-the 
proximate cause, or origin of specialized individual organic forms- 
of the different organs and organisms of living beings. 
The principal arguments of Dr. Lehmann are battlings with 
shadows. The former physiologists were generally ignorant *of 
chemistry, and could not recognize chemical facts in the living 
organism. They were denied, and the matter of the animal eco- 
nomy was believed to be exempt from the laws of chemical affinity. 
All its actions were imputed to vital forces, exclusively existing in 
the organism. These opinions are attacked and refuted, though no 
longer advocated by modern physiologists. 
The identity of the chemical actions of living beings and of in- 
organic bodies is now generally admitted. It is granted " that the 
same chemical laws preside over the constitution and transforma- 
tions of different compounds, whether organic or inorganic." Ad- 
mitting the accuracy of this proposition, it does not authorize the 
assertion, that "all the differences observed between these two 
different classes of bodies are accidental, relative, and have nothing 
essential." Will it be affirmed that when an unfecundated egg is 
placed in the conditions for incubation, and the result is its putre- 
faction, while, in a fecundated egg, the albuminoid contents are 
transformed into blood, muscles, viscera, nerves, brain, heart, ves- 
sels, and organs of sense, and it is endowed with special sensibilities, 
with consciousness and voluntary movements, that these two classes 
of phenomena are only accidental, relative, and non-essential? 
It is certainly true, that chemical affinities and molecular actions 
are indispensable to produce the varied special proximate organic 
materials of the fluids, tissues, organs, and the living organism of 
the chick. But, without the presence of the germ, a fact neglected 
by Dr. Lehmann, this extraordinary play of specific chemical affini- 
ties, and specialities of chemical actions, and the development of some dr. lehmann's doctrine of vital forces. 
43 
hundred organic forms, included in the living being, from the form- 
less organic matter, could not have occurred. Certainly, here are 
displayed, in the two classes of bodies-inorganic and organic- 
differences that are not accidental, or relative, and that are essential. 
The same general facts are observed in the germination of seeds. 
If the germ cell at the hilum of a seed be artificially ruptured, and 
it be placed in the same circumstances of germination with a per- 
fect seed, the first will rot, while, in the other, are formed dextrin, 
grape sugar, cellulose, and albuminoid compounds; and these or- 
ganic matters are developed into the tissues and organs of a perfect 
plant. 
In these, which are but single series of organic phenomena, the 
most absolutely marked and undeniable differences are to be ob- 
served between the two classes of bodies: it is impossible to regard 
them as "accidental, relative, and non-essential." 
These phenomena have occurred in living beings with absolute 
constancy, in all generations of animals and vegetables, and are so 
completely under the control of positive law, that any one, or all 
of them, can be predicated and foretold with as much certainty as 
any chemical or physical action. 
Another argument urged as conclusive is the following: "We 
should not lay down a new force, a general specific cause, until we 
have eliminated all other possibly operative forces from the group 
of phenomena in question. A proof of the existence of a purely 
vital force is hence only to be obtained by an exclusion of every 
physical force.'' A full assent is given to the conditions of the 
argument; and it is affirmed most positively that the only phe- 
nomena-the exclusive attributes of a vital or organic force-the 
creation from a liquid formless plasm of typical organic forms, and 
organic instruments to execute physical, chemical, mechanical, and 
dynamical actions, in the living organism, which are operative only 
during life, cannot be explained by any one, or all of the physical 
forces combined. They ar.e absolutely excluded. Let the subject 
be expressed in special terms, and it is affirmed that neither heat, 
nor light, nor electricity, nor magnetism, nor gravity, can construct 
an eye, can form a retina, heterogeneous in its organic materials) 
complicated in the distinct organized anatomical elements of its 
structure, and endowed with a special sensibility-light and colors- 
manifested normally only when excited by a special external agent, 44 
REMARKS ON 
the luminiferous ether. Nor can they generate the black pigment 
cells of the choroid coat, for the express purpose of suppressing 
the luminous rays, which have accomplished their impression, with- 
out which there can be no distinct vision; nor cause the formation 
anterior to the retina of the vitreous humor and the crystalline 
lens, admirably adapted in form, shape, and density, to refract the 
rays of light into a focus, the distance from the retina calculated so 
truly, as to subtend on it a visual focus, in which is a perfect repre- 
sentation of external bodies. The formation of this organic optical 
apparatus, constructed in the foetus included in the ovum or uterus, 
excluded from the direct operations of the physical forces except 
heat, it is affirmed, is absolutely inexplicable by the physical forces, 
or by any known physical process or actions. 
The insuperable difficulties presented by these facts, it is sought 
to evade by assuming that, as the causes of physical actions are 
unknown, and that new physical phenomena may be discovered, a 
resort to a new force is useless and unscientific. But it will not be 
pretended that the causes of physical actions will ever be better 
known than they are at present; and, whatever new physical actions 
may be discovered, they cannot differ in their nature from those of 
the present known physical actions. They will be unable to furnish 
any new light to solve the nature and origin of phenomena that 
reach far beyond the range of the physical forces; to which physical 
forces and actions are accessories, but cannot hold the relation of 
productive causes. 
From the admission by Dr. Lehmann, in his argument " that a 
new force may be assumed in science, whenever groups of pheno- 
mena are inexplicable by any known forces," the assumption of 
an organic or vital force, as distinct from physical forces, and as 
presiding over the developments of the organic forms of living 
beings, is an authorized and legitimate deduction. 
A third argument, and the last that will be noticed as having a 
bearing on the question is, "that the idea of a vital force is illogical; 
for a force is merely the abbreviated expression of a law from 
which the causal connection of certain phenomena may be deduced; 
and that a vital force corresponds to no law." 
This statement proves that Dr. Lehmann has not investigated the 
physiological facts of embryology or organic development, or he 
could not have so broadly asserted that the vital or organic force dr. lehmann's doctrine of vital forces. 
45 
corresponds to no law, and is not a necessary cause of multitudi- 
nous consequent phenomena. 
So far is this statement from being correct, it may confidently be 
asserted that the evidences of law, of causal connection and depend- 
ence are as strong, as palpable, in the phenomena, the direct results 
of organic or vital force-those of organization-as are to be found 
in any of the physical forces. A few facts will prove this position. 
Prevent the spermatozoon from reaching the egg, no monadiform 
germ cell, the primary form of all animals, is produced. Let this 
germ cell be artificially broken or injured, and no blastoderm will 
be formed; injure the blastoderm, and either no embryon and chick 
will be developed, or this last will be imperfect. 
Here are law and causal dependence and connection. Professor 
Owen, in his Hunterian Lectures (ed. 1855), has demonstrated that 
" every animal, in the course of its development, represents some of 
the permanent forms of animals inferior to itself, but it does not 
successively repeat them all, nor acquire the organization of any of 
the inferior forms which it transitorily typifies. One organic form, 
the microscopic infusorial monad, is either permanently or transito- 
rily represented throughout the animal kingdom. Other forms are 
represented less exclusively in the development of the animal king- 
dom, and may be regarded as secondary forms. These are the 
polype, the worm, the tunicary, and the lamprey. They are second- 
ary in relation to the animal kingdom at large, but are primary in 
respect to the primary divisions or provinces." 
In the above statement is demonstrated the subordination to a 
law, to a great overruling force in the organic world, on the pre- 
sence and action of which depend the type of organic forms, and 
the order of development of animal organisms. 
In the immutable harmony of organic nature, in the unchangeable 
characters that mark the distinction of species, genera, families, 
orders, and classes, are displayed unmistakable signs of the opera- 
tion of laws, of causal connections and dependency. Cuvier 
demonstrated the persistence, as he believed the permanency of 
species, and certainly the permanency of genera and families, by his 
anatomical researches. Goethe, as it were by a philosophical inspira- 
tion, had previously conceived and evolved the idea of the "Unity 
of Organization." In 1790, he enunciated the generalization, that 
" all the parts of an animal, taken together or separately, ought to 
be found in all animals." This deep-reaching thought of the 46 
REMARKS ON" 
philosopher anteceded the empirical demonstration of the anato- 
mist. Oken and Geoffroy St. Hilaire struck on the same vein of 
thought, and by their researches and investigations established its 
truth, and made it the crowning fact of organic science. This 
widest and boldest generalization in natural science is, in the 
organic world, what Newton's law of gravity is in the universe. 
In the infinitude of the phenomena and forms and beings that 
compose the organic world, the universality and dependence of 
causal connections and special law, and in the evidences of its 
ever-during beauty, order, and harmony that pervade organic nature, 
is demonstrated the supremacy of a dominant force, far transcend- 
ing the physical forces in the higher nature of its productions, and 
more exalted character of its powers, influences, and relations. In 
its operations it appears as a ray emanating from the divine intelli- 
gence, stamping on each created living being types of organic 
structures, a revelation in material forms of the creative ideas of 
the Eternal Artificer of the universe. That force cannot be more 
appropriately expressed, than as the Organic or Vital force. This 
conclusion will no doubt be condemned as unscientific by physicists 
generally. In the present state of knowledge, the inexplicable and 
inconceivable in the physical, and still more in the physiological 
sciences, constantly cross our path, and arrest our investigations. 
Knowledge, science, philosophy, have their ultima thule, beyond 
which lie the vague and dreamy realms of conjecture. 
The sciences are the facts or phenomena discovered in the order 
of their connection, and interpreted by man's intelligence, such as 
they exist in the world exterior to itself. Indissolubly connected, 
they form the circumference of a vast circle, each advancing as it 
progresses, and is developed like radii, and meet in one common 
centre. That centre is the incomprehensible, the infinite; it is the 
first Eternal Cause-the creative God! 
It is always to me an assurance that the line of inquiry pursued 
is the true one, when its direction tends obviously to this termina- 
tion. Whenever investigation is turned from this course, it is 
invariably lost in misty and groundless hypotheses. 
In dissenting from the author's views of organic or life force, 
there has been no purpose of disrespect, or intention to undervalue 
his knowledge and the authority of his opinions on the special 
branch he has cultivated. It has been rendered necessary by the 
manner in which the subject has been treated. Almost exclusively DR. LEHMANN'S DOCTRINE OF VITAL FORCES. 
47 
physiological, it has been handled as a chemical question. All that 
has been urged by the author as to the extent, variety, and import- 
ance of the chemical actions and influences of chemical laws in the 
living organism is perfectly just; but to force chemical affinity and 
its laws from their appointed ordinances in nature, is not correctly 
scientific, and leads to serious errors and misconceptions. Yet such 
a perversion, it strikes us, takes place when physics and chemistry 
are summoned to explain the origin and the permanent constitution 
of the typical forms of organization, differing so widely from the 
molecular processes and actions, exclusively the results of their 
special activity and energies in the plan of creation. 
In adopting the handbook of Dr. Lehmann as a manual of 
organic chemistry for the use of the students of the University, and 
in recommending his original work of physiological chemistry 
for their more mature studies, the high value of his researches and 
the great weight of his authority, in that important department of 
medical science, are fully recognized.