18 STORRS AGRICULTURAL EXPERIMENT STATION. 
is the animal that is not thus weakened. It is probable, also, 
that other factors connected with the care of high bred stock, 
their being more generally housed, being kept warmer, tend 
to weaken the vitality of the animal so that the greater preva- 
lence of tuberculosis in high bred stock is probably explained 
by conditions surrounding such stock rather than by anything 
peculiar in breed itself. 
It is found, further, that the amount of tuberculosis varies 
with the sex of the individual. Apparently, female cattle are 
somewhat more liable to the disease than are male cattle. The 
difference, however, is quite slight. 
It is found that the amount of tuberculosis varies with the 
size of the herd which any individual farmer produces. This 
is a significant fact, and at first somewhat surprising. If a 
farmer has a large herd of animals, one or two hundred or 
more, it is very likely to be infested, while the smaller herd of 
his neighbor may be free from it. Large herds show, also, a 
considerably greater per cent. of the disease than small herds. 
It is not difficult to understand that this should be so. An 
owner of a large herd is constantly buying new animals and 
thus increasing the chance of infection. dn large herds, too, 
the chances. of contamination of one animal by another are 
decidedly greater than in small herds. If a farmer keeps only 
a few animals he is less likely to buy infected creatures, and 
hence the chance of infection is greatly reduced. At all events 
this is found to be almost universally the case. Tuberculosis 
is more prevalent among large herds. 
Taking all these things together, it is evident that any esti- 
mates as to the amount of tuberculosis present in our herds is 
almost valueless. And yet the figures that are given may be, 
at all events, interesting, and will certainly serve to indicate a 
prevalence of tuberculosis rather greater than has been gen- 
erally believed. Taking the statistics which are derived from 
slaughter houses as the most reliable, we find that apparently 
the amount of tuberculosis among the herds in Europe varies 
from a minimum which cannot be given to as high as over 
fifty per cent. in all animals over one year of age. In the city 
of Leipzig, where the best records are kept, the amount is about 
thirty-three per cent. It must, of course, be understood, 
in speaking of these figures, that in these cases we have actual 
tuberculosis as discovered by post mortem examination. We 
must remember, too, that advanced cases of tuberculosis do 
not reach the slaughter-house, the owner knowing that the 
