458 
A. W. CLEMENT. 
the head of every cow in the herd. There was no manger in 
the passageway, so the calf was fed from the barrow used to 
carry the food to the cows. 
The heifer’s appetite was voracious, but it continued to 
become thinner and weaker, its coat became dry and staring, 
it suffered with a racking cough, there was an occasional dis¬ 
charge of creamy matter from the nose, and in six weeks from 
the time of purchase it died. No autopsy was made. Some 
six weeks thereafter some of the cows commenced to cough ; 
they gradually grew thin and yielded less milk. Early in 
March, a cow died that had been affected as above for some 
w$eks. Before the last of September nine cows had either 
died or had been sold while still able to walk away. Some of 
these cows were opened and examined by a veterinarian and 
were found to have died of tuberculosis. In September, less 
than one year after the introduction of the heifer, the herd 
was tested with tuberculin ; nineteen animals reacted and were 
slaughtered and all were found to be tuberculous. 
In some instances, as the one quoted, the disease spreads 
with amazing rapidity through almost the entire herd ; in 
other cases the progress is gradual and slow, and after a herd 
has harbored it for years, but a small percentage of the animals 
become affected. 
The study of the predisposing causes of tuberculosis of 
cattle is an important one, and one that is at present quite in¬ 
complete, although a number of undemonstrated theories in 
explanation of this subject have been advanced. 
Among the points that require special study are the in¬ 
fluences of the following factors on the predisposition to 
tuberculosis: heredity, feeding, stabling, climate, season, 
breed, productiveness, especially in reference to the dairy 
cow, and age. 
It seems probable that excessive stress has been laid on 
some of the above points, since observations show that con¬ 
tinued association with tuberculous animals will lead to in¬ 
fection in a large percentage of cases, notwithstanding the 
other conditions. But they do, to a certain extent, influence 
the rapidity of the spread of the disease. 
