
TUBERCULOSIS, IN CATTLE, 29 
dividuals and part of them from cattle. These were kept under 
identically the same conditions. A number of calves were 
inoculated with the bacilli from the different sources. The 
experiments have really only begun, but the result of the first 
series was very striking. It was found that the calves which 
were inoculated with the bacilli that had come from cattle be- 
came seriously infected with tuberculosis, which was rapidly 
diffused and developed to a very great extent. They became, 
in other words, severe cases of tuberculosis. It was found, on 
the other hand, that the animals that were inoculated with the 
bacilli which had come from human beings, while they did de- 
velop the disease, developed it only in a mild type. There 
were produced only slight local tubercles, which appar- 
ently soon ceased to develop, and the animals suffered prac- 
tically nothing from them. In one case the disease extended 
rapidly and produced serious trouble; in the other case the dis- 
ease was so slight as to become soon ended. These experi- 
ments seem to indicate that the variety of tubercle bacillus that 
is capable of producing the severe type of the disease in man 
is. not capable of producing the severe type of the disease 
among animals. Of course, if this is a fact, and the facts must 
be tested by further experiment before they can be accepted as 
certai tly true, it will follow that we cannot look upon human 
beings as an important means of distribution of the diesase to 
the animals. While we may recognize such infection as a 
possibility and perhaps as occurring rarely, it certainly will 
follow from these facts that the chief sources by which the 
disease is distributed to the cattle are other than through their 
attendants. 
(c) TRANSMISSION OF TUBERCULOSIS FROM ANIMAL TO MAN. 
There is no subject connected with tuberculosis of more 
general interest than the question as to whether the disease 
is ever or commonly carried from the domestic cattle to 
mankind. The discovery of the identity of the disease in man 
and animals has raised this question, and, since the year 1884, 
when the tubercle bacillus was first discovered, the question as 
to the transference of the disease from animal to man has been 
prominently before the public mind, as well as a subject of 
scientific investigation. During the fifteen years that has 
elapsed, many modifications of the original opinions have 
arisen, and the attitude which the scientific world takes toward 
