


TUBERCULOUS COWS AND THE USE OF THEIR MILK. 251 
little value. ‘These facts must be borne in mind in attempting 
to make deductions from experiments. Owing to the short 
time these experiments have been in progress it would be 
unwise to attempt to draw any definite conclusions from the 
work, but the following deductions based on these and other 
observations and experiments seem warranted: 
I. Bovine tuberculosis is usually a disease of slow develop- 
ment, depending for its progress on conditions which favor the 
spread of the specific germs, and the extent to which the ani- 
mal organism may be subject to these germs, owing to bad 
surroundings, poor ventilation, etc. The general vigor of the 
animal, or its power to resist the action of the germs, will also 
affect the progress of the disease. 
2. The stage at which the disease may attack the udder of 
the cow, or become so generalized as to develop the germs in the 
lacteal ducts, is a matter of more or less uncertainty. In the 
earlier stages of the disease, or when no physical symptoms 
appear, such as hard lumps, or stringy, or “‘ gargety’’ looking 
milk, udder affection is. comparatively rare. Increasing evi- 
' dence tends to imply that there is little danger of spreading the 
disease by the use of milk of diseased cows so long as the 
udders remain unaffected. 
3. Calves fed on the milk of tuberculous cows with no udder 
affection are not liable to acquire the disease from this source. 
In the tests made at this Station calves have been fed for peri- 
ods of five to sixteen months upon the milk of cows which it is 
teasonable to suppose are tuberculous, but without the disease 
having appeared in the udder, and in no instance do these 
calves show symptoms of the disease either by the tuberculin 
test or physical examinations. 
