24 STORRS AGRICULTURAL EXPERIMENT STATION, — 
is the common means of distribution through our herds of 
cattle. In previous years there. was no tuberculosis among 
cattle in Japan, but a few years ago it was brought to the 
country. by certain imported animals, and has subsequently 
extended quite widely, largely, it is true, among the imported 
cattle. In Denmark it was first introduced by cattle from 
Schleswig, and has since spread widely. It is a belief, also, 
that the same was the history in the United States, that the 
tuberculosis in our cattle is to be traced to the importation of 
certain animals from the Old World who had the disease. 
- When the question is raised as to exactly how the disease is 
carried from one animal to another, the answer is not so easily 
given. The disease can only be transmitted from one indi- 
vidual to the second when the tubercle bacillus itself finds an 
exit from the diseased animal and finds some entrance into 
the body of a healthy animal. The common channels of en- 
trance are the mouth and nose, although it also may gain access 
to the body through the sexual organs, through the mammary 
glands, and through wounds. The last three methods ‘of infec- 
tion are of comparatively little importance. To pass from one 
animal to another the bacilli must, of course first find an exit 
from the infected animal. The most common location of the 
disease among cattle is in the lungs, although it is present also 
in a very large amount in the other organs. Cattle, however, do 
not void sputum from the mouth, and thus sputum, which is re- 
garded as the most common means of the distribution among 
man, can play little or no part in the distribution among cattle. 
Tt is true that the bacilli as they come from the lungs may pass 
up into the mouth and the nose of the animals, and when there 
are slight discharges from the nose and mouth, as is not uncom- 
mon, these may be means by which the germs are eliminated 
from the animal. It is quite easy to understand how a cow 
suffering from tuberculosis in the lungs may thus infect the 
water in the watering trough from which she drinks, by dip- 
ping her nose into ‘the water, and thus allowing some of the 
germs which are in the nose or mouth to pass into. the water. 
It is easy to understand, then, how a second animal, drinking 
from the same trough, may get the germs into her own mouth 
and stomach and thus: become infected. While this is a possi- 
ble method of distribution, we must recognize, however, that 
among cattle the discharges from the lungs do not, as a rule, 
pass from the mouth, but are swallowed, and consequently the 
bacilli will tend to pass into the stomach rather than to pass 
