314 
Tuberculosis in Animals, and 
contagious diseases. An examination of cattle in a herd in 
which a tuberculous cow has been kept for many months, or even 
a couple of years, usually fails to detect any appearance of the 
disease in the animals associated with it. In cattle as well as 
in man the surrounding circumstances have often much to do 
with the extension of the disease. 
The ingestion of tubercular matter by animals has proved 
the means of inducing the disease, and from this the question 
naturally arises whether the flesh or milk of all tuberculous 
animals should be condemned as dangerous and unfit for human 
food. There is great diversity of opinion on this point, for, while 
some maintain that the flesh and milk of all such animals should 
be destroyed, others hold that if the lesions are localised and 
confined to the lungs the meat and milk may be used without 
danger. It is true that the deposits of tubercle are seldom found 
in the meat, and the feeding experiments have proved that even 
in the advanced stages of the malady, when the milk proved 
infective to guinea-pigs and rabbits, the flesh in the raw state 
was harmless. 
Meat is always cooked before being used as human food, and 
it has been demonstrated by Koch, Lingard, and others that 
a boiling temperature for a few minutes is sufficient to destroy 
the vitality and infective power of the bacillus ; but milk is 
generally used as food without cooking, more especially in the 
case of children. 
Tuberculous milk must therefore be looked upon as dangerous 
and likely to be the means of producing the disease in young or 
weakly subjects consuming it. The chief difficulty in determining 
whether the milk of any particular cow or cows is dangerous lies 
in the inability of the veterinary surgeon to say whether there are 
any tubercular deposits in the udder. Milk may contain these 
organisms and even a skilled bacteriologist fail to find them ; 
their absence in the few drops which he examines is no guarantee 
that they may not exist. Recent experiments in America have 
demonstrated that where tuberculous cows showed no signs of the 
disease in the udder their milk proved infective to rabbits and 
guinea-pigs fed witli it. The results of the feeding experiments 
all tend to prove that the milk from tuberculous cows, if given 
to animals in the uncooked state, possesses a very much higher 
infective power than the flesh. 
The question whether legislation for this disease in Great 
Britain is necessary, and if so, what form it should take, lias 
recently given rise to much discussion. Before, however, enter- 
ing on this part of the subject it may be as well to notice th e 
