FROM THE AUTHOR. 
THE 
ETIOLOGY AND PROPHYLAXIS 
OF THE 
TUBERCULOUS DISEASES. 
J. C. WILSON, M.D. 
[.REPRINTED FROM THE MEDICAL NEWS, JUNE 8, iS8q. | THE 
ETIOLOGY AND PROPHYLAXIS 
OF THE 
TUBERCULOUS DISEASES. 
Being the Address in Medicine before the Medical Society of the State of 
Pennsylvania, at its Thirty-seventh Annual Session, held in 
Pittsburg, June 4, ifcSg. 
By J. C. WILSON, M.D., 
Of Philadelphia. 
Knowledge, like the hard woods, is of slow growth. 
Auenbrugger worked seven years upon that discovery 
which he gave to an unheeding profession as the “ In- 
ventum Novum.” Half a century later it was rescued 
from oblivion by Corvisart, to be extended and perfected 
in another quarter of a century by Piorry. Laennec had 
already acquired a reputation by his practice and writ- 
ings, when, in 1815, he invented the stethoscope. Four 
years later he published his Treatise upon Mediate Aus- 
cultation and the Diseases of the Lungs and Heart, but 
almost a quarter of a century elapsed before this method 
of clinical investigation became popularized among med- 
ical men, and was generally taught in the schools of Eng- 
land and America. Jenner spent nearly twenty years in 
investigations and experiment before he published, in 
1798, his Enquiry into the causes and effects of the cow- 
pox. 
Yet each of these discoveries revolutionized that de- 
partment of the art of medicine which it affected, and 
to-day no student is entitled to receive the degree, which 
marks his admission to the profession, who does not 
know more of percussion than Auenbrugger, at least as 
much of the principles which underlie auscultation as 
Laennec, and unless he has easily acquired the essential 
facts of that beneficent discovery which cost Jenner 
twenty years of toil. 
These things were in the old days. We live, if not in 
an era of more impatient intellectual activity and keener 4 
inquiry, at least in a time of the infinitely more rapid dis- 
semination of information. A flash of electricity, a turn 
of the press, and that which happened yesterday is known 
all over the civilized world. But this is news, not knowl- 
edge. 
Lister’s memorable introductory lecture in the Univer- 
sity of Edinburgh on “the germ theory of putrefaction, 
the basis of a new mode of treatment which finds its 
application in all departments of practice,” was deliv- 
ered in the autumn of 1869. It makes a little pamphlet 
of twenty-two pages. The time was ripe for the princi- 
ples set forth in that publication, and in others which 
quickly followed it. Much that had gone before led up 
to them. We think at once of the work of Latour, of 
Schwann, of Pasteur. The facts were convincing. Many 
of the details of Lister’s early methods were, it is true, 
unnecessary, some were faulty; but the underlying 
thought was right. If not a new truth, it was certainly 
a new application of truth. 
Nearly twenty years have elapsed, and the seed sown 
by Lister has grown and multiplied and brought forth an 
abundant harvest. The surgery of to-day stands in bright 
contrast to the surgery of that day. The antiseptic pro- 
cedure has enormously widened its scope and increased 
its precision. Its capacity to relieve suffering and pro- 
long life is abundantly enlarged. The contrast is so 
striking that it has become customary to speak of the art 
of to-day as the New Surgery. 
This revolution was not brought about in a day. Lis- 
terism and the operative technique which it inspired, 
made for a long time slow and halting progress. Preju- 
dices were to be overcome, old habits of thought given 
up, the traditions abandoned, and it was only little by 
little, notwithstanding the readiness of inter-communica- 
tion and the eagerness for new and better things which 
characterize the present, that the New Surgery came into 
being. 
Koch, who had previously published a paper entitled 
“ Investigations into the Etiology of the Traumatic In- 
fective Diseases,” announced his discovery of the tuber- 
cle bacillus and its relation to tuberculosis in March, 
1882. As an example of scientific research, this work 
stand unequalled in the history of medicine. Had it led 
to no practical results, its thoroughness, the logical 
se’quence of the various progressive stages of the investi- 
gation, its completeness, the rigid tests to which he sub- 
jected his results, make it a model for investigators in 
every department of biology. 
Koch demands, in order to determine whether or not 5 
a given bacterium is the cause of a certain disease, the 
fulfilment of the following requirements : 
(a) The special bacterium must be present in all cases 
of the disease. 
(&) It must be separated from other microorganisms, 
and from all matter found with it in the diseased animal. 
(<;) Thus freed from all foreign matter, it must be 
capable, when properly introduced, of producing the 
disease in healthy animals. 
(<f) The bacterium must be found properly distributed 
in the animal in which the disease has been induced. 
Not only did he devise and elaborate the technical 
methods by which these rules can be carried out, but he 
saw that every one of the conditions was absolutely ful- 
filed in the investigation which he had undertaken. The 
proof was final; the demonstration complete. The germ 
theory was no longer a working hypothesis; it had be- 
come, in regard to the tuberculous diseases at least, an 
incontrovertible fact. So admirable was Koch’s account 
of his investigation, that Trudeau, in the Adirondacks, 
with but little knowledge of microscopy and very imper- 
fect apparatus, much of which he constructed himself, 
was enabled by following a translation of the original 
report to repeat the research step by step, and verify the 
results by the inoculation of pure cultures of the bacillus. 
The labors of Lister had not only made the discovery 
of special pathogenic microorganisms possible ; they had 
made it a necessity. There were many workers in the 
field ; the fulness of time had come. Obermeier had al- 
ready in 1873 discovered the spirillum of relapsing fever. 
Had it not been the tubercle bacillus, some other patho- 
genic bacterium would have been brought to light in its 
causal relationship to some specific morbid process. But 
to Koch is due the lasting honor of having first clearly 
demonstrated the part played by microorganisms in the 
etiology of disease, and of having thus laid the founda- 
tion of the science of bacteriology. 
This discovery, modestly as it had been announced 
by its author, was at once heralded throughout the world 
and received with acclamation. Klebs, Cohnheim, and 
others had already, without reserve, placed tuberculosis 
in the group of the specific infectious diseases. To have 
found the infecting principle itself, or at all events the 
carrier of the infection, seemed a boon almost beyond 
comprehension. Its importance appealed to the dullest 
attention. The mortality statistics of pulmonary con- 
sumption are, unfortunately, too familiar. To this dis- 
ease alone fifteen per cent, of all deaths are to be at- 
tributed. Add to these the deaths due to tuberculosis of 6 
other organs, of the joints, of the meninges, of the peri- 
toneum, then swell the list by the cases cut off by inter- 
current diseases or accident, and the result is simply 
appalling. The tuberculous diseases are not endemic 
the world over, they are epidemic. Consider that a large 
proportion of the cases are chronic, progressive, inexora- 
bly disabling, and it becomes easy to realize that this 
group of diseases exerts an influence upon the family 
and upon society that nothing but the apathy begotten 
of hopeless familiarity renders endurable. It is easy 
then to understand the enthusiasm with which Koch’s 
discovery was received. Men thought of the maxim 
Causa sublata tollitur effectus. 
The cause being now found, nothing seemed easier than 
that it should be dealt with, and that, as a consequence, 
one great scourge of the human race would become 
preventable, if not curable. Certainly, one of the first 
effects was to arouse both the profession and the people 
from the apathy into which they had fallen in regard to 
these diseases. Those who had the opportunity and 
training proceeded to verify and extend Koch’s investi- 
gations, with the result, not only of acquiring a mass of 
information in regard to the life-history of the bacillus 
itself, and a more exact knowledge of the pathology of 
the tuberculous diseases, but also with the acquisition of 
like knowledge in regard to other bacteria, and the part 
played by them in the pathogenesis of many other in- 
fections. 
Others turned their attention without delay to thera- 
peutic investigations, having for their object the destruc- 
tion of the tubercle bacillus. It is needless to enumerate 
the methods of antiseptic and germicide treatment which 
have been the outcome of these efforts. They are fresh 
in your memory. Based upon insufficient knowledge of 
the mode of growth and development of the tubercle 
bacillus in the tissues, they have one after another been 
tried and found wanting. 
These failures have afforded an apparent justification 
to that contingent of the profession who, preferring dark- 
ness to light, because the light has not yet flooded all 
the obscure places, still refuse to recognize the etiological 
relationship between the tubercle bacillus and tuber- 
culosis. 
Seven years have now passed. A host of workers 
have collected a vast array of facts which rest upon a 
sure basis of truth. These facts are being sorted and 
placed in proper relation with each other. A critical 
observer sees that steady progress is being made. In 
surgery much has been accomplished ; yet the results in 7 
the diminution and cure of the visceral tuberculous dis- 
eases are not encouraging. The growth of knowledge is 
slow; it is not the less sure. He does not to-day seem 
too sanguine who looks forward to practical results of 
the greatest importance, if not in the cure, at least in 
the prevention, of pulmonary consumption. 
Some broad generalizations are already possible: 
i. Tuberculosis is a specific infectious disease. 
Its exciting cause is the tubercle bacillus. Its etiology 
is the natural history of that parasite. The predisposing 
influences are those conditions, both inherited and ac- 
quired, which favor the implantation and growth of the 
bacillus. Its pathology is summed up in the statement 
of the facts which relate to the development of the bacil- 
lus in the tissues, and the effects which it produces locally 
and upon the organism at large. Its diagnosis no longer 
depends upon the anatomical character of the lesions, 
but upon the presence of the tubercle bacillus and upon 
its inoculability. 
The distinction between true tubercle and pseudo- 
tubercle is now perfectly clear. Both these formations 
are composed chiefly of lymphoid corpuscles or leuco- 
cytes. They are the result of an irritative hyperplasia. 
But the tubercle is the result of a chronic or persistent 
inflammation produced by a continuously acting irritant, 
and spreading by the infection of neighboring parts and 
by the circulation. The pseudo-tubercle may be produced 
by the mechanical irritation of small foreign particles. 
It constitutes, upon the subsidence of the active process, 
simply a mass of fibrous tissue, which undergoes no fur- 
ther change, and it remains single, being without the 
power of giving rise to other similar structures. 
The pathological unity of the tuberculous process, 
whatever the tissue or organ affected, however diverse 
the clinical manifestations, is at once established by the 
double test of the presence of the bacillus and the inocu- 
lability of the disease. The relationship between the 
most unlike lesions subjected to these tests becomes ap- 
parent. The lung packed with tubercle or riddled with 
its lesions to the same cause which pro- 
duces the insignificant tuberculous wart upon the hand 
of the pathologist who dissects it; intestinal ulceration, 
hyperplasia of the mesenteric glands, peritonitis, fistula 
in ano, may all result from the action of a common cause. 
The pathological identity of processes producing the 
most diverse lesions in the same organ is also shown by 
these tests. So-called chronic catarrhal pneumonia of 
the apex, gray miliary tubercle, diffuse, tuberculous, 
cheesy infiltration in the lungs, are dissimilar manifesta- 8 
tions of the same pathological process. Joseph Coats 
maintains the view that the changes of fibroid phthisis 
are essentially tuberculous. The ‘‘ solitary tubercle ’ of 
the brain, which is usually yellow and caseated, and 
may be as large as a walnut, is due to the same cause as 
the miliary tubercles occasionally found scattered in 
other parts of the brain substance and so familiar in the 
meninges. 
A large proportion of the cases called scrofulous are 
now known to be tuberculous. We no longer think that 
scrofulous individuals are especially liable to become 
tuberculous, for tubercle bacilli are almost constantly 
found in so-called scrofulous lymph-glands, bones, and 
joints. After a time the local tuberculosis becomes ex- 
tended or generalized. 
Neelsen places tuberculosis along with enteric fever, 
leprosy, and syphilis in his fourth group of the germ dis- 
eases—namely, the mycoses with tissue proliferation or 
infected ulcers. 
2. The constitutional manifestations are not directly 
due to the bacilli, but to toxic principles evolved during 
their growth and multiplication. 
The bacteriologico-chemical researches of Hoffa, 
Brieger, Vaughan, and others, within the past few years, 
have done much to clear up the relation between the 
special pathogenic germs of the infectious diseases and 
their symptomatology. They have also rendered neces- 
sary a new definition of the infectious diseases. In the 
words of Vaughan and Novy, “An infectious disease 
arises when a specific, pathogenic microorganism, having 
gained admittance to the body, and having found the 
conditions favorable, grows and multiplies, and in so 
doing elaborates a chemical poison which induces its 
characteristic effects.’’ 
Nencki obtained upon chemical analysis of tubercle 
bacilli, water 88.82 per cent., solids 11.18 per cent. The 
solids yielded 22.7 per cent, of substances soluble in 
alcohol and ether, which, when used experimentally 
upon animals, showed the presence of a tetanizing 
poison. This substance has not been isolated. Bonardi 
demonstrated in tuberculous sputum alkaloidal organic 
bases, which introduced into rats and guinea-pigs rapidly 
produced remarkable disturbances of the nervous sys- 
tem. This experimenter believes that these organic 
bases may explain the fever, sweating, disturbance of 
the circulation, and other general symptoms of the dis- 
ease. 
The wide range of intensity in the constitutional phe- 
nomena is to be explained, only in part, by the varying 9 
reaction of different individuals to morbific agencies. It 
is more largely due to the extent and activity of the 
local process. Nor can we attribute the constitutional 
disturbances to suppuration associated with local tuber- 
culous processes, as in the case of the breaking down of 
pulmonary infiltrations, or in joint diseases ; for consti- 
tutional disturbances of the same kind, and of every de- 
gree of intensity, are developed in tuberculous meningitis, 
tuberculous peritonitis, and in those rapidly developing 
cases of consumption in which the lungs are found 
studded with miliary tubercle without extensive caseation 
or suppuration. Furthermore, decided constitutional 
disturbances are not infrequently associated with circum- 
scribed lesions of insignificant extent, while enormous 
cavities, occupying the large portion of a lobe, are not 
incompatible with fair nutrition and moderate health for 
a period of years, in cases in which, after extensive de- 
struction, the tuberculous process, as such, has come to 
an end. 
Finally, the frequency with which obsolescent tuber- 
culous lesions at the apex of a lung are found in indi- 
viduals dying late in life from non-tuberculous diseases, 
suggests the possibility that a tuberculous process, termi- 
nating in resolution, may confer upon the individual in 
whom it has occurred subsequent immunity from the 
disease. The very lesions show that such individuals 
have at one period of life been susceptible, while their 
repeated exposure to the infecting principle during sub- 
sequent periods may be fairly assumed. 
3. Tuberculosis is directly and indirectly communicable 
from the affected to the healthy individual. 
In other words, it is a contagious disease. Koch has 
demonstrated the fact that tubercle bacilli never develop 
or multiply outside of the body of animals. They re- 
quire for their development a constant and uniform tem- 
perature of 85° to ioo°; they, however, retain their vi- 
tality for an indefinite period outside of the body and 
under conditions extremely unfavorable for the develop- 
ment of other microbes. 
Cadeac and Malet found that tuberculous matter dried 
and pulverized was, after one hundred and two days, capa- 
ble of giving rise to the disease. Schill and Fischer 
maintain that it only loses its virulence after six months. 
Pietro asserts that well-dried sputum may retain its in- 
fecting power for nine or ten months if maintained at a 
temperature of 770 F. Bacilli with or without spores 
show an equal tenacity of life. The distribution of tu- 
bercle bacilli outside of the body is, however, by no 
means as extensive as was formerly thought. The in- 10 
vestigations of Cornet prove conclusively that they are 
to be found in greatest numbers in the immediate neigh- 
borhood of affected individuals ; that they are not found 
in the dust collected from the abodes of individuals free 
from consumption, nor are they to be found in the 
apartments occupied by consumptives who habitually 
and exclusively use the spit-cup. 
The experimental production of tuberculous diseases 
by the inoculation of sputum or other substances con- 
taining tubercle bacilli is a familiar fact. When ani- 
mals thus inoculated are killed in a short time, the lesions 
are invariably found restricted to the point of inoculation 
and the neighboring lymph-glands. In view of this fact, 
Cornet holds that the assumption that the lungs are the 
seat of an especial predilection for the development of 
the tuberculous process is absolutely untenable, the fre- 
quency of pulmonary consumption, as compared with 
other forms of tuberculous disease, being due to the 
favorable conditions presented by the respiratory organs 
for the implantation of the infecting material. Numer- 
ous experimenters have shown that air passing over 
moist surfaces is incapable of taking up tubercle bacilli; 
the expired air which passes over the moist surfaces of 
the respiratory tract, of cavities, of collections of bacilli- 
containing pus or muco-pus not yet expectorated, does 
not carry the infecting principle, and is, therefore, in- 
capable of communicating the disease. 
Nor do the expectorated matters themselves, so long 
as they remain moist, comply with the conditions neces- 
sary for the communication of the disease to healthy in- 
dividuals except by direct contact or inoculation. When 
dried, however, they are capable of dissemination through 
the atmosphere in the form of fine dust bearing bacilli 
and spores, which, being inhaled by susceptible individ- 
uals, cause the disease. Desiccation is a necessary re- 
quirement for the dissemination of tubercle bacilli and 
spores by means of the atmosphere, and the most 
favorable conditions for such dissemination are found 
within doors. Wet weather and a moist atmosphere are 
unfavorable. 
The fact that the disease is most frequent in crowded 
quarters supports the view of dissemination by means of 
dried sputum. Flick, in his remarkable investigations 
in Philadelphia, found that ninety per cent, of infected 
houses had an infected house joining them, while thirty- 
three per cent, of the infected houses showed more than 
one case. These facts warrant the conclusion that con- 
sumption is communicated by contact, by association, or 
by living in close proximity. 
Flick also found that pulmonary phthisis conformed 11 
to the laws which govern the spread of contagious dis- 
eases in other respects. The grouping of the cases is 
the same, and the localization is influenced by the age 
of those predisposed to the disease. It prevails in cir- 
cumscribed epidemics, which are, however, less notice- 
able because the disease is of long duration, whereas the 
ordinary contagious diseases run their course rapidly. 
From this point of view, the gradual infection of sev- 
eral members of a household, previously free from the 
disease, in the course of a few months or years after the 
introduction of a case, becomes intelligible. So, also, 
married couples infect each other; and those who nurse 
relatives suffer from the disease, females being more liable 
by reason of their closer ministration. Leibermeister 
has observed many cases where previously healthy 
families became infected one after another after removal 
to a house formerly occupied by a consumptive patient. 
It is, however, a question of the seed and the soil. A 
large proportion of individuals enjoy an immunity which 
appears to be complete; many others, while capable of 
infection, show a remarkable resistance to the invasion 
of the tuberculous process which either undergoes re- 
solution in the region infected or makes a tardy progress 
interrupted by more or less prolonged periods of quies- 
cence. Between cases of this form and the cases called 
phthisis florida, the disease manifests every degree of 
intensity. 
These variations in the degree of susceptibility to the 
disease and its development serve to explain some of the 
objections which have been urged with more or less 
force against the doctrine of the contagiousness of pul- 
monary consumption. 
Those who assert that if consumption were contagious 
the human race would have rapidly become extinct, 
overlook the fact that a considerable number of persons 
in every community, especially those living outdoor 
lives, and those who are not brought into association 
with consumptives in confined apartments, are not ex- 
posed; and, secondly, the fact that a certain proportion 
of individuals, either by reason of the resistant power of 
their tissues, or of the integrity of the mucous surfaces of 
the air-passages, or from other causes not well under- 
stood, possess a more or less complete immunity. Those 
who deny the contagiousness of phthisis on account of 
the infrequency with which medical men, nurses, and 
other attendants upon consumptives are said to contract 
it, advance an argument which rests upon insufficient 
grounds. A certain proportion of individuals thus 
brought into habitual contact with consumptives enjoy 
an immunity ; others while susceptible doubtless escape 12 
infection by reason of the thorough ventilation and 
cleanliness of well-regulated wards and sick-rooms. 
Physicians and attendants upon those suffering from 
cholera or the fevers, even in hospitals in which con- 
siderable numbers of such patients are collected, do not 
often contract the disease, yet who will deny that accord- 
ing to their special modes of transmission, cholera, enteric 
fever, and typhus are contagious ? 
Another difficulty lies in the localization of the tuber- 
culous process in its beginning, and its tardy develop- 
ment, the time which elapses from the infection and the 
manifestation of the disease being not infrequently so 
long that the original exposure, even when traceable, is 
forgotten. 
The often quoted statement of Williams in regard to 
the exemption of nurses and attendants in the consump- 
tive hospital at Brompton is valueless in the light of ad- 
vancing knowledge. The cleanliness and ventilation of 
a well-ordered hospital tend to reduce the dangers of in- 
fection. The statistics of Baer and others show a mor- 
tality in prisons that is nearly four times as great as out- 
side, the majority of cases developing not during the 
earlier years of imprisonment but toward its close. The 
fact that more than fifty per cent, of nuns in cloisters die 
of tuberculosis speaks for itself. 
The attendants in hospitals come and go; many of 
them remain in the service for short periods only. The 
statistics of Williams are incomplete in not showing the 
subsequent history of the personelle upon which they 
are based. On the other hand, the elaborate recent 
statistics of Cornet prove incontestably that attendants 
upon the sick show as a class an enormously increased 
death-rate, the increase being due to tuberculosis and 
other infectious diseases. 
4. It is not in the ordinary sense hereditary. 
Prior to the discovery of the tubercle bacillus, the 
direct transmission of tuberculosis from the parent to the 
child was very often assumed. The frequency with which 
the children of consumptive parents were affected with 
the disease was regarded as proof of its transmission 
by inheritance. Even tuberculosis developing in adult 
life in those previously presenting every appearance of 
health, was assumed to be of hereditary origin, the fre- 
quent absence of tuberculosis in the parents notwithstand- 
ing, for it was assumed that hereditary tuberculosis might 
skip a generation or two. 
Baumgarten supports the view that congenital tuber- 
culosis may be latent, the bacilli remaining inactive in 
certain tissues for years, or throughout life, unless called 
into activity by traumatism or other influences. 13 
The number of cases in which tubercles have been 
actually found in the foetus is very small. The view that 
congenital tuberculosis may be due to the semen or ovum, 
is a pure hypothesis unsupported by proof. The opinion 
that it may be derived from the maternal blood by way 
of the placenta, rests upon a small number of positive 
facts. Malvoz found that microorganisms may pass the 
placenta only when it is diseased. Charrin found in a 
seven and a half months foetus of a tuberculous woman, 
which died three days after birth, tuberculous lesions of 
the abdominal organs. Merkel discovered cheesy nodules 
in the palatine arch, the lymph-glands, and in the neigh- 
borhood of the hip-joint, but not in the lungs of a child 
of a tuberculous woman, which died directly after birth. 
Should the view held by Baumgarten be proved, it will 
explain the presence of tubercle in the lymph-glands, 
bones, and marrow, and the occurrence of tuberculous 
meningitis, which is so common in young children. 
Even in very young children, the primary infection fre- 
quently takes place by way of the lungs, a fact fully in 
accord with what is now known of the mode of contagion, 
the relation between the mother or nurse and the young 
baby affording the fullest opportunity for the communi- 
cation of the disease. 
The conclusion that enteric fever or scarlet fever is 
hereditary, would rest upon very nearly the same basis 
of fact upon which the doctrine of the hereditary trans- 
mission of tuberculosis has been assumed, namely, that 
the parents of those having the sediseases had previously 
suffered from them, and that, in a few rare instances, the 
child of an infected mother has shown the characteristic 
signs at birth. 
In regard to the hereditary transmission of tuberculosis 
among the domestic animals, the statistics of the Berlin 
abattoir are not without interest. Among 320,000 calves, 
17 were tuberculous; whereas, among 398,000 cattle, 
there were no less than 8000 tuberculous. 
5. A rational, scientific prophylaxis is practicable both 
as regards individuals and communities. 
The part played by heredity in direct distribution and 
propagation of the tuberculous diseases is insignificant 
as compared with the influence of contagion. The few 
children of tuberculous parents born tuberculous have 
died promptly; those who develop the disease in infancy, 
die early in life; the infected children of tuberculous 
parents who reach adult age are those who long suffer 
only from tuberculous diseases of the lymph-glands and 
the bones, and are not, in the absence of pulmonary 
lesions, likely to disseminate the infecting material. 
The chief avenues of infection are the digestive and 14 
respiratory tracts. The disease is acquired by infected 
food, and by the inhalation of air containing tubercle 
bacilli and spores; other methods of invasion are infre- 
quent and relatively unimportant. 
The only sources of the infecting material are those 
discharges from the bodies of infected human beings 
and domestic animals which contain the tubercle bacilli 
and their spores. Of these, the chief are cow’s milk used 
as food, and the matters expectorated by patients suffering 
from pulmonary phthisis, which is not likely to infect 
unless dried and inhaled as dust. The flesh of tubercu- 
lous cattle does not cause tuberculous diseases in those 
who partake of it; there is. in fact, no case on record of 
the communication of the disease by these means. The 
liability of its communication by milk is increased where 
there is tuberculous inflammation of the udders of the 
cows. It is important, therefore, that all milk used as the 
food of infants should be sterilized by boiling, and until 
used it should be kept protected from the atmosphere. 
The infection by way of the intestinal tract, frequent 
as it is, especially in childhood, is notably less common 
than infection by way of the respiratory surfaces. 
As Cornet has shown, the only effectual prophvlaxis is 
in the proper care of the sputum. In this respect tuber- 
culosis presents a strong analogy to enteric fever, of 
which it has been said, “ that measures of prophylaxis 
will be efficient in proportion to the strength of our belief 
in the material nature of the typhoid poison, and in the 
possibility of destroying it or preventing its spread.” It 
is the duty of the physician to see to it that no case of 
infectious disease under his care becomes a focus of con- 
tagion. In enteric fever we have long recognized a dis- 
ease in which this rule can be effectively carried out by 
means of the disinfection of the stools. It is evident that 
in pulmonary phthisis we must follow the same principle 
of prophylaxis, the one efficient procedure being the 
proper disposition of the bacilli-laden expectoration. 
The difficulties in the practical application of this rule 
lie, on the one hand, in the chronic nature of a large 
proportion of the cases of the disease, and, on the other, 
in the deeply rooted prejudices or indifference of patients 
in regard to the matter. Cornet has formulated the rule 
that a phthisical patient should never under any circum- 
stances expectorate on the floor or in a handkerchief, but 
always in a spitcup ; this is the one thing needful. The 
cup should contain a little water, and be frequently emp- 
tied into the sewer, where the contents sooner or later 
undergo destruction, or at all events pass beyond the 
reach of inhalation by man. The cup should be fre- 
quently washed with boiling water. A cup has recently 15 
been devised, and is sold in the shops in this country, 
which consists of a small metal frame in which a folded 
paper cup is set; when a quantity of sputum has accumu- 
lated, the paper may be removed and burned with its 
contents. 
The floor should be sprinkled with water before sweep- 
ing, and the sweepings destroyed by burning. The 
clothing and bedding of tuberculous patients should be 
disinfected by prolonged boiling. The walls of apart- 
ments occupied by patients should be frequently rubbed 
down with bread, which may then be burned. Carpets 
and curtains should be shaken in the open air at a dis- 
tance from houses, and exposed at intervals to the air 
and sun. 
The acceptance and universal practice of prophylactic 
measures would warrant the hope that the prevalence of 
pulmonary consumption will diminish, as have the septic 
diseases following surgical operations and puerperal 
fever, under a rational prophylaxis. 
Such a result is not only theoretically possible ; its ac- 
complishment in the course of time is, in a high degree, 
probable. This hope has the support of strong analogies 
in the records of the past; the great scourges of man- 
kind have prevailed during more or less extended his- 
torical epochs, and then passed away. The plague 
which ravaged all parts of Europe during the Middle 
Ages, which depopulated villages and laid waste districts, 
which, in the form of the black death, swept over 
Europe in the fourteenth century, and destroped in three 
years twenty-five millions of inhabitants, disappeared 
from England with the great outbreak of 1665. Only 
twice during the present century has this ptst shown 
itself in Western Europe. The disappearance of the 
plague was probably due to the conjoint influence of a 
rigorous quarantine and altered methods of living. It 
has been said in regard to Europe, that when the shirt 
came in, the plague went out. 
Typhus, which devastated Europe from the fifteenth 
century until the end of the first quarter of the present 
century, of which Murchison says, “A complete history 
of typhus would be the history of Europe for the last 
three and a half centuries,” has almost burnt itself out. 
Here and there in the seaport cities of Great Britain it 
still smoulders, but in the great modern campaigns of the 
American War and the Franco-Prussian War typhus 
fever was unknown. Its disappearance is unquestion- 
ably due to that prophylaxis which comes of a clear 
knowledge of its causes, and to the improved hygiene of 
modern life. 
Leprosy was for thirteen centuries endemic in Great 16 
Britain ; cases were still in existence on the borders of 
Scotland toward the close of the last century. To-day 
no indigenous case is to be found within the British 
Isles. 
Smallpox was for centuries one of the greatest scourges 
of mankind. Scarcely a decade passed in which the 
disease, sweeping over great areas, did not decimate the 
inhabitants of one country or another. To-day we have 
no dread of it beyond the fear lest prolonged and com- 
plete immunity may beget neglect of the precautions 
which protect us. 
The discovery of the tubercle bacillus has not been 
without practical results. Without it these generaliza- 
tions were impossible. It has given us, in place of ob- 
scurity, confusion, uncertainty in regard to pulmonary 
consumption and the other tuberculous diseases, a posi- 
tive etiology, a clear pathology, a rational therapeutics, 
a hopeful prophylaxis. These are great gains at the 
end of seven years. 
But it has done more than this. It has pointed out 
the direction of future work, and indicated possibilities 
never before dreamt of. The news of Koch’s discovery 
burst upon the world like a flash that grew faint, leaving 
the eyes dazzled. The knowledge which Koch has given 
us is like the dawn, which steadily grows brighter and 
brighter, until the clear day shows the perfect truth. 
How shall we fitly characterize those rare men who, 
by sheer intellectual force, have found and given to their 
fellowmen new truths ? By what metaphor shall we 
make their greatness plain ? They are bright stars— 
suns—in the intellectual firmament, in the steady light 
of whose genius the work of mankind may be carried 
on as in the open day. I speak not of science in gen- 
eral, nor for the other sciences, but in medicine a cen- 
tury has given us five—that son of France, dead at 
thirty-one, whose philosophic mind conceived those 
generalizations which laid the foundation, not only for 
modern physiology, but for modern biology; that Ger- 
man, no longer young, to whom nothing human is with- 
out interest, busy in the affairs of men to-day as always, 
both in science and in politics, whose labors laid the 
foundation for the science of modern pathology; that 
Englishman, to whose clear insight mankind for nearly 
a century past, and for all time to come, owes the incal- 
culable boon of deliverance from smallpox; that other 
Englishman, who to-day lives to see in the result of his 
labors the new surgery; and, lastly, him to whom we 
owe that discovery upon which rests the young science 
of bacteriology—they are called—names never to be 
forgotten !—Bichat, Virchow, Jenner, Lister, Koch.