230 
j. m’fadyean. 
is necessary in order to protect human beings from the risk 
of infection through the ingestion of tubercle bacilli in the 
flesh of animals. 
On the other hand, if it can be shown that the agents of 
infection are frequently disseminated throughout the system, 
there is at least nothing improbable in the supposition that 
the foetus may in many cases be infected in litero; and the 
practice of partial condemnation of tuberculous carcases 
must be pronounced inadequate to safeguard the public 
health. 
There are several lines along which the information neces¬ 
sary to guide to a correct conclusion regarding these disputed 
points may be sought. In the first place it is obvious that a 
study of the distribution of the lesions in naturally contracted 
cases of tuberculosis is fitted to throw light on the mode of 
dissemination of the bacilli within the body, and to furnish 
evidence for or against the theory that the blood-stream is a 
common vehicle for the transport of these organisms. In 
the second place we may call in the aid of experiment, intro¬ 
duce tubercle bacilli into the blood-stream, and observe 
whether the resulting lesions -have a distribution agreeing 
with that observed in natural cases of the disease. Or, finally, 
we may in cases of natural or experimental tuberculosis 
institute a search for tubercle bacilli in the various fluids and 
tissues of the body, either by direct microscopic examination 
or by inoculating these fluids and tissues into the bodies of 
animals known to be easily infected with the disease. The 
main purpose of this article is to record the result of some 
investigations that I have recently carried out along the last 
mentioned line of inquiry. 
i. Experiments with the Blood of Tuberculous 
Animals. 
Before proceeding to state the details of these experi¬ 
ments, it may be well to describe the precautions that were 
taken with a view to preventing accidental infection of the 
experimental animals. 
In each instance the blood was taken from the jugular 
