268 TUBERCULOSIS. 
are of any significance. In the United States the results differ 
so widely that figures have, as yet, little value. Sometimes every 
animal in a herd is found to be tuberculous, while other whole 
herds are entirely exempt. In the eastern States the percent- 
age is Jarge, and in some localities it appears to approach the 
figures given for Denmark. When the numbers of infected animals 
in a herd range from o to 100 per cent, it is evident that no resulting 
average would be of any significance. 
Increase of the Disease. Is bovine tuberculosis on the 
increase ? Statistics are so uncertain as to make any conclusion 
difficult. Certainly we hear much more of the disease than we 
did a few years ago, and the percentages reported to-day are much 
higher. The knowledge of the disease is, however, of very recent 
date, and the increasing interest in the subject has caused a more 
and more careful inspection of slaughtered animals, which has 
resulted in a constant increase in the number of reported cases. 
Even in the same slaughter houses and under the same management, 
the percentage of tuberculous animals reported has been increasing 
year by year in such a way as to seem to indicate an alarming 
increase in the last fifteen years. But a considerable part of this 
increase is clearly due to increased experience and carefulness in 
inspection. To what extent this factor explains it, and to what 
extent there is an actual increase in the disease, no one can pretend 
to say. It is, therefore, impossible to state whether bovine tubercu- 
losis is rapidly or slowly increasing or remaining stationary. 
But taking all facts together, the practical uniformity with which 
the percentage of reported cases has increased in the last years, 
has led to the general belief that the disease is actually and some- 
what rapidly increasing among our herds. 
But although no definite statistics can be given, either as to 
the prevalence of the disease or its increase, bovine tuberculosis 
is abundant enough. It presents a very serious problem to the 
farmer. Entirely independent of the question of its relation to 
human tuberculosis, the disease, as it exists among cattle, is a 
menace to the dairy industry. The amount of financial injury 
that it does to the farmer each year is very great far in advance of 
