192 
JOHN M. PARKER. 
Nocard and May both got similar results, while Hirchbirger 
“inoculated milk from 20 different tuberculous cows into the 
peritoneal cavity of guinea pigs, and found it capable of infection 
in 11 cases.” (Journal of Comp. Path., Sept., 1890.) 
These figures are valuable, and they go to show that even 
where the disease is well marked and the animal highly tubercu¬ 
lous, the danger is not so very great; for we must remember 
that in inoculation experiments the milk from the diseased cow 
is injected directly into the tissues, and if any baccilli are 
present they must find lodgment; and in feeding experiments 
the animal experimented on is fed on this milk continuously, 
with every opportunity for contracting the disease, and yet r 
notwithstanding the favoring-conditions, we find only a small 
proportion of experiment animals becoming tuberculous, and, 
as in natural conditions, when we mix this milk from tuberculous 
cows with the milk from healthy' cows, the danger is just so 
much the less ; if, then, we remove these diseased cows from 
the herd (even if we only make a physical examination in 
detecting the disease) and use only the milk from apparently 
healthy cows, we reduce the danger to a minimum. 
In summing up his report to the Society for the Promotion 
of Agriculture, Dr. Ernst says: “While transmission of tuber¬ 
culosis by milk is probably not the most important means by 
which the disease is propagated, it is something to be guarded 
against most carefully.” 
These conclusions of Dr. Ernst’s, as has already been pointed 
out, are drawn from experiments with cows known to be dis¬ 
eased only through physical examination ; that is to say, in 
those cases tiie disease was well advanced and the animals were 
evidently diseased animals, and it follows of course that care 
should be taken to exclude the milk of all such animals from 
the market. 
But it does not necessarily follow that cows reacting to 
tuberculin, but showing no physical evidence of disease , are 
equally dangerous. 
In this line it would be interesting to see the results of a 
