454 
A. W. CLEMENT 
Then followed the discovery of inoculation by Lagnnec, 
the inoculation experiments of Villemin, the diagnosis of 
pulmonary tuberculosis by the presence of elastic tissue in 
sputa of phthisical patients, and finally the most brilliant 
achievement of modern medical science—the discovery by 
Koch, in 1882, of the cause of tubercle and the etiology of the 
disease. This brilliant discovery set at rest all doubts as to 
the nature of the disease, and proved beyond all question the 
identity of the disease in all animals. 
The tubercle bacillus gives rise to anatomical changes 
either in the form of miliary tubercles or in caseous inflam¬ 
mations. It produces secondary infection either by being car¬ 
ried in the blood current to other parts of the body or by 
traveling along natural channels. The most common form 
of primary infection in cattle is in a caseous bronchitis or 
broncho-pneumonia, or in calves more commonly in the form 
of tabes mesenterica. 
The disease is world-wide in its distribution, and probably 
affects all classes of animals. It has received much, and is 
daily receiving more and more the attention of governments 
as an enemy which probably destroyed more lives annually 
than all of the so-called scourges and wars put together. 
Many conflicting reports have been published as to the ex¬ 
tent of the disease among the cattle of this country, but most 
of them were based upon too insufficient data to make them 
of much value. We have no regular inspection of herds nor 
a complete inspection of meat. It is only possible to glean 
facts relating to the extent and distribution of the disease, 
incidentally, when cattle are examined with other ends in 
view. Even if we had an organized inspection of herds the 
results of such an inspection would not teach us how much 
tuberculosis is present among our cattle because the disease 
is notoriously hard to discover in the living animal, except 
when advanced, and breeders and farmers who have had 
some experience with it are clever enough to remove animals 
that show the first suspicious symptoms. It is only possible 
by an extensive examination with tuberculin, or through a 
thorough and well organized system of meat inspection, that 
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