Importance and Value 
OF - 
Experimental Research 
DOCTORATE ADDRESS 
DELIVERED AT THE GRADUATING EXERCISES OE THE CO EL LEGE OE 
PHYSICIANS AND SURGEONS, CHICAGO, ILL., 
feb. 2i, 1887. 
- BY - 
N. SENN, M. D., Milwaukee, Wis. 
Professor of Principles and Practice of Surgery and Clinical 
Surgery. 
Reprinted from the Western Medical Reporter, March, tSRj. 
Press of 0. F ANSELL CO., 196 Clark St., Chicago Importance and Value 
-OF- 
Experimental Research 
DOCTORATE ADDRESS 
DELIVERED AT THE GRADUATING EXERCISES OE THE COLLLEGE OE 
PHYSICIANS AND SURGEONS, CHICAGO, ILL., 
EEB. 21, 1887. 
BY 
N. SENN, M. D., Milwaukee, Wis. 
Professor of Principles arid. Practice of Surgery and. Clinical 
Surgery. 
Reprinted from the Western Medical Reporter, March, 1887. 
Press of C. F. ANSEUU CO., 196 Clark St., Chicago. Importance and Value of Experimental Research. 
N. SEJNN, M.X). 
A Doctorate Address delivered at the Fifth Annual Commencement Exercises of the College of Physi- 
cians and Surgeons, Chicago, Feb. 21, 1887. 
Professor of Principles and Practice of Surgery. 
Genteemen of the Graduating 
Ceass:—To-day marks a new era in your 
lives. The time you have been so anx- 
iously awaiting has arrived. The dreams 
of your youth are realized. You have left 
the college building where you spent so 
many days in acquiring a knowledge of 
the healing art, and in recognition of 
work well done you have just been re- 
ceived into the ranks of a great and noble 
profession. The pleasant relations which 
have existed between us as teachers and 
students have come to a close. As teach- 
ers we congratulate you, as colleagues we 
welcome you and extend to you the right 
hand of fellowship. With parental soli- 
citude we shall follow you into the arena 
of active professional life, fully confident 
that every one of you will meet with well 
merited success. 
made in medicine and surgery and the 
allied sciences during the last two decades 
is unparalleled in the history of medicine. 
One discovery has followed another until 
we have witnessed a complete revolution 
in the treatment of injuries and disease. 
Text-books of a few years ago that were 
then considered as standard authorities 
are now consigned to the shelves of the 
antiquarian, as the very principles upon 
which their teachings were based have 
undergone a radical change. You have 
been instructed in the most recent ad- 
vances pertaining to your profession. 
You have been made familiar with both 
ancient and modern literature, and have 
thus derived the benefit resulting from 
the accumulation of knowledge which it 
has required centuries to develop. You 
owe to science a debt which can only be 
paid by faithful and persevering study 
and research, in enlarging its boundaries 
and in increasing its store of wealth. 
While you are no longer students under 
the supervision of teachers you should 
dedicate your future lives to the stmTy 
and improvement of your chosen profes- 
sion. We have inherited a trust which 
can only be invested profitably by hard, 
unselfish work. The study of medicine 
is inexhaustible and affords ample scope 
to occupy all your leisure moments. As 
teachers we have simply laid the founda- 
An honorable struggle for a remuner- 
ative practice is justifiable and desirable, 
but a successful career is not always to be 
measured by weight in gold. One of the 
great objects in life must be to become 
contributors to science. Even at the 
very threshold of your professional career 
you have incurred a heavy debt, in the 
payment of which some of the very best 
efforts of your lives will be required. 
During yonr pupilage you have enjoyed 
advantages that were not in reach of stu- 
dents even a few years ago. The progress 4 
tion for your medical education and must 
leave it to your own efforts and inclina- 
tions to complete the structure. Com- 
mence your life-work with a firm deter- 
mination to continue your studies in a 
systematic manner. It is not only neces- 
sary for you to keep familiar with the 
current medical literature, but you should 
also strive to render material aid in the 
future growth and development of our 
science. A reward greater in value than 
gold, and more enduring than fame, is a 
consciousness of having contributed to 
the increase of knowledge. 
case of injury or disease. Rational treat- 
ment is based upon sound physiology. 
Experimentation is part of a system,— 
the physiological system, and part of a 
method,—the experimental method, A 
scientific investigator is never a random 
experimenter. A comprehensive and ac- 
curate knowledge of the ancient and 
modern literature, and an intimate ac- 
quaintance with everything that is known 
relating to the subject is essential for 
successful work. As modern medicine 
and surgery are so intimately related to 
and associated with physiology, it is 
proper to ask: “What has experimental 
research done toward the development of 
the latter science?” 
With a view of pointing out to you the 
right direction in which such work can 
be accomplished, I have selected as the 
subject of my address, “The Importance 
and Value of Experimental Research.” 
Experimental research implies the neces- 
sity of resorting to vivisection. It is not 
my intention to argue in justification of 
this method of investigation, as vivisec- 
tions in original researches are performed 
only when questions in hand cannot be 
solved bjr any other method of study, and 
always with a definite object in view, and 
with this restriction no intelligent com- 
munity has the moral right to interfere. 
Erasistratus thought that the arteries 
contained air. Galen was a diligent ex- 
perimenter, and his observations soon 
taught him that this was not the fact. 
He found that when an artery was cut 
blood escaped. He believed, however, 
that the arteries contained, besides blood, 
air or vital spirits, and that their function 
consisted in distributing this vivifying 
substance to the whole body. He was 
the first great experimental physiologist, 
and the knowledge derived from vivisec- 
tion had elevated him to a position of 
prominence and influence which survived 
him for centuries. The physiology of 
the circulation after his time remained 
much in the same condition until the 
beginning of the 17th century. The great 
motor power of the heart was unknown 
to medical men of that time and the 
direction of the blood current through 
the vessels had not been ascertained. 
Practical observation at the bedside, and 
upon battlefields, had failed to familiar- 
ize the physician with the true mechanism 
of the circulation. The observations 
made upon living animals were directed 
more toward the study of anatomy than 
physiology. In the beginning of the 
Modern medicine and surgery are 
founded upon a study of the organs of 
the body and their functions, that is, 
upon a knowledge—the more thorough 
the better—of the mechanism with which 
they have to deal. Empirical medicine 
and surgery have a foundation since they 
rest upon the observation of isolated 
facts, but the mere collection of informa- 
tion without reasoning upon it is useless, 
and mauy disconnected facts cannot con- 
struct a system capable of further devel- 
opment. A thorough knowledge of the 
structure of the body with which the phy- 
sician and surgeon has to deal, the rela- 
tions of its functions in health will enable 
him to act promptly and intelligently in 5 
17th century Harvey followed the foot- 
steps of Galen and laid the foundation for 
modern physiology by his discovery of 
the circulation. Malpighi and Leouwen- 
hook, the founders of microscopical an- 
atomy, were the first to observe the pas- 
sage of the blood from the right to the 
left side of the heart through the pulmo- 
nary capillaries of a living frog by vivi- 
section, thus adding the last link to 
Harvey’s chain of evidence. Only a few 
years ago the researches of Waller and 
Cohnheim made on the circulation of the 
blood in lower animals have demonstrat- 
ed the migration of white corpuscles 
through the capillary walls—a discovery 
which furnishes an adequate explanation 
of many pathological conditions, which, 
without it, would have remained shrouded 
in darkness. 
blood supply to the various organs through 
the medium of the action of the nervous 
system upon the organs of circulation. 
Gaspardus Asellius, a distinguished 
Italian anatomist, in 1662, while experi- 
menting upon a dog which had just had 
a full meal, accidentally discovered the 
lacteal vessels which appeared as “a 
number of fine white cords,” which he at 
first supposed to be nerves, but which, 
when punctured, proved to contain milky 
fluid. As at this time it was the general 
belief that the liver was the exclusive 
haemato-genetic organ, he failed to search 
for the proximal termination of the lac- 
teal vessels and entertained the belief 
that they terminated in the liver, an 
opinion which prevailed until Jean Pec- 
quet, while experimenting for another 
purpose, discovered the thoracic duct, and 
by further research succeeded in tracing 
the general course and distribution of the 
lymphatic system. 
Intracardiac pressure was first studied 
by Stephen Hales, who published his 
observations in 1732. The same subject, 
which of course could only be studied 
upon living animals, was investigated by 
Poiseuille, and more recently by Alfred 
W. Volkmann, who published the result 
of his researches in a large volume in 
1850, entitled “Die Haemodynamik nach 
Versuchen.” As a result of these inves- 
tigations a number of ingenious instru- 
ments, as the kymograph, sphygmo- 
graph, and cardiograph have been devised 
which have rendered material diagnostitial 
aid to the physician and surgeon, ascer- 
taining the most delicate changes in the 
circulation, and are most valuable means 
in studying the fluctuations of disease. 
Haller, the great physiologist, demon- 
strated by his careful observations on 
living animals the independent muscular 
contractions in the arteries, a discovery 
fully confirmed by the experiments of 
Hunter and Thomson. Claude Bernard, 
Brown-Sequardand others established by 
experimentation the regulation of the 
The ancients entertained the most 
vague ideas in relation to the respiratory 
functions, believing that the air passed 
through the lung into the cavity of the 
chest, from there into the heart, where it 
came into direct contact with the blood. 
This opinion represented the whole 
knowledge upon this subject until the be- 
ginning of the 17th century, and was en- 
dorsed by such famous authorities as Har- 
vey, Hall, and Boerhave. A series of 
experiments made by Haller demonstrat- 
ed to the satisfaction of physiologists the 
mechanism of the respiratory function. 
Mayow, by experiment and logical induc- 
tion, came to the conclusion that the 
atmospheric air was a compound, contain- 
ing as one of its elements a body to 
which he assigned the properties pos- 
sessed by oxygen, which from its supposed 
analogy to nitric acid he called nitro-ae- 
rial spirit. To this element of the air 
he attributed an active and essential part 6 
in the process of combustion and respira- 
tion. Black, in 1759, showed by experi- 
ments the presence of carbonic acid in the 
expired air; and in 1770, Priestly proved 
by the same means the analogy of respi- 
ration to combustion, and asserted that 
atmospheric air in its passage through the 
pulmonary circulation lost some of its 
oxygen. Lavoisier’s skillful and labori- 
ous experiments resulted in an accurate 
knowledge of the chemical changes 
which take place in the inspired air dur- 
ing the respiratory process. More recent 
experiments have determined almost 
with arithmetical precision the amount 
of oxygen consumed and carbonic acid 
exhaled by an individual during a speci- 
fied time. Lowrer found when examining 
the open thorax of a living animal that 
the difference between the color of ar- 
terial and venous blood took place in the 
capillaries of the lungs and referred this 
phenomenon to a chemical change in 
the blood itself. The true explanation of 
this change was furnished by Priestly, 
whose experiments convinced the scien- 
tific world that the alteration was due to 
the purifying of the blood by means of 
the oxygen of the air. Our ancestors 
entertained a very peculiar idea concern- 
ing the complicated process which we 
now consider essential for healthy diges- 
tion and assimilation. The transforma- 
tion of food into chyle was supposed to 
be effected entirely by the moisture and 
heat of the stomach producing a change 
which they termed “concoction.” Then 
appeared the mechanical theory which 
advanced the idea that the mechanical 
division of food in the stomach by tritu- 
ration constituted the most important 
part of digestion. Still later it was be- 
lieved that the food introduced into the 
stomach underwent a process of putre- 
faction before it could be absorbed and 
utilized in the body. 
Experimental research again had to 
come to the rescue of science to demon- 
strate the fallacy of all of these absurd 
doctrines. Spallanzani and Stephens 
showed that the mucous membrane of 
the stomach secreted a digestive fluid— 
the gastric juice—and made careful ex- 
periments to determine the effects of this 
substance upon different kinds of food. 
Our knowledge of digestion as elucidat- 
ed further by Hunter, Cruikshank, Ma- 
gendie, Voit and many others is based al- 
most exclusively upon the results derived 
from patient and persevering experimen- 
tation on animals which have succeeded 
in solving the problems of digestion, ab- 
sorption and nutrition, until this part of 
physiology has reached an enviable de- 
gree of perfection. The physiology of 
the nervous system furnishes one of the 
strongest and most convincing claims in 
favor of the indispensable value of experi- 
mental research. 
Galen gave public demonstrations illus- 
trating the effects of injuries to the cere- 
bro-spinal centres in animals. He divid- 
ed the spinal cord in the cervical region 
and showed how this procedure affected 
the respiratory and other movements. 
He also studied carefully the phenomena 
following section of the cord in other 
places, and, by comparing the different 
results, obtained a fair knowledge relat- 
ing to the more important functions of 
this nervous centre. 
P'rom this time little or no progress 
was made until Sir Charles Bell, Mageu- 
die and Mueller again resorted to im- 
proved methods of experimentation to 
throw more light upon this important sub- 
ject. The motor function of the anterior 
roots of the spinal nerves was clearly 
pointed out by Bell in a few carefully con- 
ducted experiments and his views were 
subsequently confirmed and elaborated 
by Magendie. The numerous and accu- 7 
rate experiments made by Mueller upon 
the anterior and posterior roots of the 
spinal nerves in frogs lead to accurate con- 
clusions as to the more important func- 
tions of the spinal cord. 
The value of experimental research 
from a practical standpoint becomes 
more apparent when we contemplate the 
achievements of modern surgery. The 
effects of the different anaesthetics had to 
be carefully determined on animals be- 
fore it was deemed prudent and safe to 
apply them in practice. Subcutaneous 
injections of anodynes were used in the 
laboratories for years with a view of pre- 
venting pain before this prompt and re- 
liable method of relieving pain found its 
way into general practice. 
Marshall Hall discovered the reflex 
function of the nervous system and per- 
sistently and enthusiastically demonstrat- 
ed the correctness of his views by experi- 
ments on animals. 
In our own day, a group of distin- 
guished and faithful investigators, among 
them Westphal, Ferrier, Hitzig and the 
lamented Gudden, have been patiently 
studying the difficult subject of cerebral 
localization, and the result of their labors 
has paved the way for successful surgical 
treatment of a number of lesions of the 
brain and its envelopes which heretofore 
invariably resulted in a fatal termination. 
Muscular contraction was attributed by 
Galen and his followers to the brain and 
the spinal cord. This idea was based 
upon the results of his experiments 
as he invariably produced muscular 
paralysis below the point of section of 
the spinal cord. Haller by his ingenious 
experiments showed the fallacy of this 
doctrine which had been handed down 
from generation to generation as an un- 
disputed fact by demonstrating the exist- 
ence of an inherent irritablity of the 
muscular fibre, entirely separate and dis- 
tinct, of the nervous system. 
Artificial respiration was practiced upon 
animals by Vesalius, Hooke, Lower and 
others, as a means ofprolon gin g life, long 
before it was applied to the resuscitation 
of human beings. Transfusion, as a life- 
saving operation, is based entirely upon 
the results derived from experimentation, 
and can be resorted to as a reliable meas- 
ure in cases of sudden dangerous loss of 
blood, a procedure which so far has 
saved more than half the cases in which 
it has been attempted. Browu-Sequard 
has shown that in cases of poisoning with 
carbonic oxide gas this substance makes 
a more stable compound with the coloring 
material of the blood, which incapacitates 
the red corpuscles from mixing with oxy- 
gen, so that in grave cases of this kind 
this surgical resource constitutes the only 
possible chance of saving life. Quite re- 
cently numerous experiments have been 
made on animals to test the influence of 
intravenous infundations of saline solu- 
tions in the treatment of acute anaemia 
as first advocated by Schwarz, and the 
encouraging results which have been at- 
tained have placed this simple and effec- 
tive procedure upon the list of well-estab- 
lished legitimate surgical resources. 
I might proceed and enumerate count- 
less instances where the results of experi- 
mental research have directly or indirect- 
ly contributed to the growth and 
development of the science of physiolo- 
gy, but you must have been convinced by 
this time that modern physiology consists 
of a systematic arrangement of facts de- 
rived almost exclusively from experimen- 
tation. Future advances in physiology 
can only be realized through the labors 
of patient and careful experimenters. 
The subject of callus production, re- 
generation and growth of bone has been 
made almost exclusively on the lower 
animals, and this part of surgical pathol- 8 
ogy is intimately associated with the 
names of Duhamel, Sir Astley Cooper, 
Ollier, Maas, Busch, Wolff, and our own 
Brainard. The results of these experi - 
ments have opened a wide field for con- 
servative surgery which has resulted in 
the saving of thousands of useful limbs 
by the substitution of sub-periosteal re- 
section for the too frequent resort to 
mutilating operations. Only a few years 
ago acute suppurative osteomyelitis con- 
stituted a subject about which but little 
was known. To-day, thanks to the 
patient labors of Kocher, Rosenbach and 
Ogston, it furnishes the most striking 
topic of the great value of experimental 
research. For years surgeons have dread- 
ed to expose the medullary tissue in bone- 
operations for fear of producing osteomye- 
litis and the disastrous consequences 
following it,—thrombo-phlebitis, pyae- 
mia and septicaemia. 
phorus, which causes increased vascu- 
larity of bone and osteo-porosis ; on the 
other hand the same author has demon- 
strated that the prolonged administration 
of minute doses produce an opposite, a 
curative effect. Numerous practitioners 
have applied the results of these observa- 
tions in practice and the majority of them 
agree with Kassowitz that minute doses 
of phosphorus constitute almost a specific 
in the treatment of rachitis. Hagenbach 
reports twenty consecutive cases treated 
successfully by this method. 
Koch’s great discovery of the cause of 
tuberculosis has revolutionized the treat- 
ment of numerous affections which wTere 
formerlv described under the vague term 
of scrofula but which are now known to 
be tubercular in their origin and in their 
tendencies. The familiar manifestations 
of so-called scrofula in children, chronic 
lymphadenitis, tumor albus, and fungous 
disease of bone, and lupus in the adult, 
are now well recognized tubercular 
lesions. In all of these affections the 
essential primary cause, the bacillus of 
tuberculosis has been found so constantly 
that the direct relationship between cause 
and effect admits of no further argument. 
But not only the germ has been found in 
almost every instance but it has been iso- 
lated and cultivated upon an artificial 
soil, and animals infected with the new 
growth have furnished the crucial test of 
the tubercular nature of the lesion—re- 
production of the same condition histolog- 
ically, pathologically and clinically. Rec- 
ognizing the danger arising from local 
dissemination and generalization through 
the vascular system, modern surgeons are 
unanimous in adopting early and thor- 
ough local measures, with a firm belief 
that by a complete removal of the local 
product, the patient is protected against 
embolic tuberculosis from the local de- 
posit. 
Experiments have shown that the mye- 
loid tissue in bone can be torn, contused, 
crushed, burned, cauterized and the sub- 
sequent inflammation will invariably as- 
sume a plastic type, provided infection is 
prevented. On the other hand, it has 
been found that in animals previously 
infected with pus-microbes, injury to the 
medullary tissue is almost invariably fol- 
lowed by suppurative osteomyelitis at the 
seat of traumatism. We are therefore 
forced to assume that the floating germs, 
which might have remained inert for an 
indefinite period of time, find at the seat 
of traumatism favorable conditions for 
localization and reproduction, and are 
the essential and direct cause of the sup- 
purative inflamation. 
That common and heretofore obscure 
disease, rachitis, has been made an ob- 
ject of patient experimentation by Kas- 
sowitz, who has shown that the disease 
can be artificially produced in animals by 
the administration of large doses of phos - 9 
Subcutaneous surgery has only been 
carried on in a scientific manner and with 
successful results since the repair of ten- 
dons after subcutaneous division was 
studied on animals by Hunter, Stromeyer, 
Von Ammon, Bouvier, Guerin and others. 
antiseptic treatment of wounds is now 
almost universally accepted, as the fun- 
damental principles upon which it rests 
are no longer theories but facts abund- 
antly substantiated by experimental re- 
search. 
The healing of wounds was made an 
object of careful experimentation by 
Hunter, Thiersch and Gussenbauer, and 
the scientific and practical information 
thus gained has been of great value in 
the advancement of surgery. Suturing 
of divided nerves has become an estab- 
lished practice since the publication of 
the results of their experimental work by 
Gluck and Wolberg. An experimental 
study of cicatrization in blood vessels 
after ligature, by Jones, Travers, Porta, 
Hunter, Zwicky, Weber and more recent 
authors, has gradually led to accurate and 
correct ideas concerning the immediate 
action of the ligature and the processes 
which are initiated, destined to effect 
definitive obliteration of the lumen of 
the vessel. 
The aetiology, pathology and morbid an- 
atomy of thrombosis and embolism could 
only be solved by patient and persevering 
experimentation by such able investiga- 
tors as Virchow and Panum. Pyaemia 
and septicaemia, the surgeon’s greatest 
enemies in the pre-antiseptic times, have 
been carefully studied by experimenters, 
and we have every reason to hope that 
work in the same direction in the near 
future will reveal the true pathology and 
relationships of these, the most important 
of all wound infective diseases. 
Experiments on dogs made by Wini- 
warter with a view to determine the feas- 
ibility of operative measures upon the 
stomach, has resulted in the establish- 
ment of pylorectomy by Billroth, which 
has established the practical application 
of the knowledge thus gained; and a long 
series of cases, which, if they have not 
resulted in adding much to the duration 
of life, demonstrate the justifiability of 
a resort to the knife in well selected cases. 
Lister’s experiments upon the use of 
the catgut ligature have led to practical 
results which alone would constitute a 
monument w’hich will render the name 
of the greatest of living surgeons immor- 
tal wherever surgery is practiced. Brown- 
Sequard studied, experimentally, how 
long the tissues can be left completely 
deprived of blood without risk of gan- 
grene, observations which led to the use 
of Esmarch’s great invention, substitu- 
tion of the elastic constrictor for the ordi- 
nary imperfect tourniquet in the preven- 
tion and arrest of hemorrhage. 
The history of intestinal surgery is inti- 
mately associated with experimental re- 
search, and the names of Jobert, Gross 
and Parks will always be remembered in 
connection with this department of sur- 
gery. Before Simon ventured to resort to 
nephrectomy in man he studied the effect 
of this operation upon animals. As a 
result of these observations extirpation 
of the kidney is now a well established 
operation and has already gained a legiti- 
mate sphere in cases heretofore aban- 
doned to certain death. The results of 
extirpation of the spleen in animals has 
satisfied surgeons that this organ can be 
removed with safety and a fair prospect 
Wound fever was studied experimen- 
tally, by Lee, Bennet, Pasteur, Colin, 
Toussaint, Weber, Breuer, Chroback, 
Bergmann and Koch. The researches of 
these men prepared the way to antiseptic 
surgery as first taught and practiced by 
Lister. The value and importance of the of success in cases of injury or local 
disease. 
value of experimental research to the 
practice of surgery, but enough has been 
said to substantiate the assertion that it is 
the foundation of modern surgery. It 
would be difficult to point out pathological 
conditions or operative measures which 
do not show the impress and great value 
of this method of investigation. The 
recent rapid advances in surgery are en- 
tirely owing to original experimental 
work. German surgery leads the world, 
because the leading surgeons of that 
country are original investigators. 
The most remote abdominal organ, the 
pancreas, has been submitted to experi- 
mental investigation, and the results thus 
obtained have shown the feasibility and 
justifiability of surgical interference in 
a number of well defined lesions. Ex- 
periments upon the liver of animals have 
shown the necessity of resorting to local 
measures in arresting hemorrhage where 
this organ is injured, and o securing a 
condition for the visceral wound which 
will favor the healing process, and, at the 
same time, prevent the disastrous conse- 
quences resulting from escape of bile and 
wound secretions into the peritoneal 
cavity. 
If the brilliant achievements of modern 
surgery are the direct outcome of experi- 
mental research, it requires no argument 
to show that future improvements will 
depend upon the same method of investi- 
gation. The American profession has as 
yet not realized the importance of original 
work. Instead of borrowers we must be- 
come producers. 
Desault, Albers, Koeberle and Hueter 
advocated the propriety of extirpation of 
the larynx, but the advisability of this 
operation had to be tested by Czerny 
upon dogs before surgeons could be in- 
duced to adopt it as a legitimate surgical 
procedure. Within a few years 96 extir- 
pations of the larynx have been made, 
with 32 cures and 64 deaths, a satisfactory 
showing when we consider that without 
it all of these patients were doomed to die 
a horrible death from asphyxia. 
I can give you no better advice on this 
occasion than to devote your leisure 
moments, from the very beginning of 
your professional career, to original work 
of this kind. The means for such an 
undertaking may be limited, but perse- 
verance will overcome difficulties. Your 
efforts will be appreciated and your alma 
mater will look with pride upon the re- 
sults of your labors. Your colleagues 
will esteem your motives to promote sci- 
ence and your work will command the 
respect of the entire profession . Another 
great advantage only to be acquired by 
operations upon animals is dexterity in 
the use of instruments and delicacy of 
manipulation in the performance of diffi- 
cult operations. Visceral surgery can 
only be learned in this manner. Opera- 
tions upon the gastro intestinal canal 
should invariably be practiced upon ani- 
mals before attempting it on man. A 
course in operative surgery on the cadaver 
is utterly inadequate to prepare a student 
Successful extirpations of portions of 
the lung in animals by Gluck and Schmid 
have encouraged surgeons to attack this 
important organ (in well selected cases), 
when the seat of localized lesions, and 
in corroboration of the value of these 
experiments I will only refer to the suc- 
cessful case of Kroenlein, who extirpated 
a piece of sarcomatous lung with a por- 
tion of the chest-wall, and the patient not 
only recovered from the operation but 
was reported in good health and without 
any indications of a return of the disease 
after two years. 
I have only enumerated a number of 
the most convincing illustrations of the sufficiently to perform gastrotoniy, intes- 
tinal resection, or even apply intestinal 
sutures with requisite speed and accuracy. 
Proficiency in abdominal surgery can 
only be acquired by operating upon living 
tissues. Ligation of arteries in their con- 
tinuities, again, is another operation in 
the technique of which you can only per- 
fect yourselves by practicing upon ani- 
mals. It must have become apparent to 
you that in order to succeed as scientific 
men you are not to lead a life of leisure. 
reading and studying the best literature. 
Take an active part in preventive medi- 
cine, and act as guardians of public 
health. Become at once original investi- 
gators. If you do all these things you 
will have no just cause of complaint of a 
surplus of time, or to seek places of idle 
amusement. The laboratory, the books, 
the journals, the microscope, the medical 
societies will become your most devoted 
and truest friends. When the curtain 
shall drop behind the scene of a busy, 
well spent life, a coming grateful genera- 
tion will inscribe your names upon the 
walls of the temple of science which you 
have helped to erect. In bidding you an 
affectionate farewell I will give you the 
watchword that will secure your entrance 
into the ranks of successful men;—work, 
uninterrupted, hard, faithful, honest 
work. 
If in the beginning of your practice 
time hangs heavy and patients come 
slowly, do not become discouraged. 
Utilize every moment of your time to 
prepare yourselves the better for your 
work. Identify yourselves with the local 
medical societies and take an active part 
in the scientific work. Keep abreast 
with the advances in medical science by