AETIOLOGY OF TUBERCULOSIS. 
171 
spleen was greatly enlarged. The infiltration of the omentum consisted, as in the 
guinea pigs of the previous experiment, of thick masses of tuberculous bacilli, em 
bedded mostly in cells. With the naked eye no knots could be seen in the lungs, 
spleen and liver, but microscopically these organs were permeated already by an 
unusually abundant tuberculous eruption. The second cat was killed after forty- 
three days, and there were already tuberculous knots as large as a millet setd in 
great numbers, quite uniformly spread over the lungs, spleen and omentum, while 
in the liver the number was comparatively small. Both cats were to havereceivt d 
a syringefull of the injecting liquid, therefore an equal quantity, but the second 
was very uneasy during the operation and only a small part of the liquid could be 
successfully injected ; on which account the tuberculosis had a considerably longer 
course, and fewer tuberculous knots developed which had time to reach a consider¬ 
able size. 
Nineteenth Experiment: Reincultur of miliary tuberculosis (No. 22) culti¬ 
vated for three months in five successive breedings, rubbed up with blood serum, 
and two cubic centimeters of this liquid injected into the abdominal cavity of a 
female dog several years old. A half cubic centimeter of the same liquid was 
injected into a male dog some months old. In the first weeks after the injection 
no change could be seen in the animals. After the third week the female dog 
lost her briskness, she ate less, and a noticeable swelling of the body occurred. 
This animal was killed at the beginning of the fifth week. In the abdominal 
cavity was a quite abundant effusion of a clear, faintly yellowish liquid. The 
omentum, mesenterium, ligaments of the womb and peritoneum were sprinkled 
over with many tuberculous knots, as were also the surface of the intestines and 
bladder. The enlarged spleen,the liver and lungs contained numerous miliary 
tubercles provided with tuberculous bacilli. The places of injection could no 
longer be recognized. The second dog appeared sick for a time, had also plainly 
an effusion of liquid in the abdominal cavity, and became emaciated; finally it 
recovered and developed very vigorously. This dog, together with a female from 
the same litter, received five months later an injection from the same reincultur, 
this time however of two cubic centimeters. The result was the same in both 
animals: for some weeks they showed no symptoms of disease, then became 
emaciated and were attacked by ascites. One animal died after five weeks, and 
then the other,which was already very weak, was killed. The information gained 
from the dissection was exactly the same as in the case of the first dog. Omen¬ 
tum, peritoneum, spleen, liver and lungs were supplied with extraordinarily many 
tuberculous knots. 
This experiment is in so far of special interest as that one dog after the in¬ 
jection of a half cubic centimeter of bacilli liquid was, to be sure, taken sick, but 
recovered. This is the only case of tuberculosis in animals which I have seen 
recover. The hope has often been expressed that, as in the case of inflammation 
of the spleen, a preventive inoculation with weakened virus might be used against 
tuberculosis. But if one recovery from tuberculosis gives protection against a 
second attack of the disease, for which, by the way, experience by the sick bed 
gives no ground of hope, then this dog should have had immunity against further 
experiments in infection. But this was not the case, and this circumstance speaks 
against the justification of such hopes. 
(To be continued .) 
