272 
JOHN M. PARKER. 
and its slow, insidious march after it has once gained a foothold 
are responsible for the existence of a large number of tuber¬ 
culous animals in all stages of the disease. In the earlier 
stages, while the disease is still restricted to a single focus, 
the animal is to all outward appearances in perfect health. 
It is only after the infection has invaded several cavities of 
the body or produced mechanical obstructions that it becomes 
manifest. The prolonged latency of the first stage of the 
disease, with little or no discharge of tubercle bacilli, raises 
the question what should be done in such cases. A compar¬ 
ison with some other infectious diseases makes the predica¬ 
ment all the clearer. 
“ When an animal becomes infected with anthrax or with 
Texas fever the specific micro-organisms begin to multiply at 
once. Within twenty-four hours in the case of anthrax, a 
few days to a week in Texas fever, the symptoms are fully 
developed and death or recovery speedily follows. There 
can be no question here concerning degree of disease or util¬ 
ity of the animal during the earlier stages. The infected 
and the non-infected are divided by sharp, unmistakable 
barriers. In tuberculosis, on the other hand, the infected 
animal is practically well during the earliest stages of disease 
and the disease may become stationary, possibly healed. In 
certain diseases the necessity for the destruction of all infected 
animals becomes imperative, because the disease must be kept 
restricted and suppressed as soon as possible. The present 
wide dissemination of this disease and its prevalence among 
other domesticated animals, such as dogs, cats, horses, goats, 
and, above all, its prevalence among man, makes the com¬ 
plete extinction of this malady an unrealizable problem.” 
Now it seems to me that the authorities at Washington 
have struck the nail full on the head in this matter. 
Before we can prevent disease, it is necessary to study 
the causes that lead to its prevalence, and then attempt to 
remedy these causes. To do any good we must get at the 
root of the matter ; we must study to prevent disease in the 
animal during its lifetime. 
Why is tuberculosis so prevalent in dairy herds? It is 
