290 TUBERCULOSIS 
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 tuberculosis 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 somewhat 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 serlous 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 
any other disease. ‘The insidiousness with which it finds its way 
into and spreads through the whole herd, even before the farmer is 
aware of its presence, the large number of cattle rendered worthless 
through its agency, especially among high-bred and valuable ani- 
mals, the suspicion which it throws upon the milk-supply, the 
injury that it does to the animal which is to be used as food, the 
great cost of tuberculosis legislation by the different States, all 
these serve to emphasize the seriousness of the problem. Nothing 
can be of more importance to the farmer than the discovery of 
some means of controlling this disease. Legislation designed to 
control it has been adopted by most states in Europe and America, 
but such legislation has usually had in mind the protection of the 
public rather than the assistance of the farmer. 
THE COMBAT AGAINST BOVINE TUBERCULOSIS 
Resistance of Cattle-—The foundation of a successful contest 
against the disease is a herd of animals in a proper condition to 
