28 STORRS AGRICULTURAL EXPERIMENT STATION. 
There is at least one prominent bacteriologist in Europe who 
goes so far as to say that this is the one source of distribution, 
and that the disease practically never is found in cattle unless 
it comes from the attendants. 
Such an extreme position is, however, held by very few. 
While no one will question the possibility that the disease may 
be carried from man to animal, it is yet impossible to point out 
any definite instance where the transference has been proved. 
This, of course, however, proves nothing in itself, because 
from the very nature of the case it would be impossible to find 
evidence for such transference, even if it occurred. But many 
other facts are indicated as showing that the transference from 
man to animals is not the common method. In the first place, 
tuberculosis among mankind has been known for many cen- 
turies. Apparently the disease among animals is new, or com- 
paratively new, and if the disease is transmitted solely from 
man to animal we uttely fail to explain how it is that the 
disease has been apparently increasing so rapidly in recent 
years, when, as we know, the disease in mankind has been 
decreasing. This in itself is enough to indicate that there 
must be some means of distribution other than from man to 
animal. Moreover, as mentioned above, in Japan the disease 
was not known among domestic animals until recent years, 
and in Denmark it is said to have been introduced by imported 
cattle from Schleswig. Tuberculosis in mankind, however, 
has been known in these countries for a long time, but it was 
not until the disease was brought by some infected animals 
that it began to extend. If these facts are thoroughly at- 
tested, of course it follows that we cannot regard man as the 
chief or even the important source of the disease in animals. 
Whether, then, the disease is transmitted from man to ani- 
mals is at the present time not definitely settled. That it may 
be transmitted is certain. That it positively is thus transmitted 
is not as yet demonstrated. That it is the chief method of the 
distribution of the disease appears to be very doubtful. 
In the most recent period-there has been a line of investiga- 
tion undertaken in our own country which apparently indicates 
that this source of distribution cannot be regarded as a serious 
one. A series of facts has led Prof. Smith of Harvard to in- 
vestigate the question as to whether the variety of the tuber- 
culosis bacillus in man and cattle is the same. The experi- 
ment consisted briefly in the following. Several examples of 
tubercle bacillus were obtained, part of them from human in- 
