NEw YorK AGRICULTURAL EXPERIMENT STATION. 31 
ment by Moore,® twelve of seventeen cows that reacted in April 
failed to react in October. These were all destroyed. They all 
contained tubercular lesions of a chronic type. They all contained 
living tubercle bacteria as proven by guinea pig inoculations. It 
is known that the lesions may remain in a chronic encapsulated 
condition for three years and the tubercle bacteria still be alive.’ 
In the cases of arrested tuberculosis the disease does not spread 
in the body, but so long as the tubercle bacilli remain alive it is 
possible that the disease may start up at any time for there is 
very little, if any, immunity established against a subsequent attack 
by the development and encapsulation of the primary lesion. One 
of us (Moore) has the records of over fifty cows that have reacted 
but failed on subsequent tests, from six to eighteen months there- 
after, to react but still later did react. Whether the late reaction 
was caused by a reinfection or by renewed activity of an encap- 
sulated, arrested lesion is not determined, but the fact that, to all 
appearance and methods of diagnosis in a living animal, the lesions 
in these animals were healing or healed and that later they 
responded to the test suggests that the first attack did not impart 
immunity. 
As a rule the tubercular changes occur in one or more of the 
following organs: (1) In the lungs or lymphatic glands draining 
them, (2) in the lymphatic glands about the head, (3) in the 
intestines and mesenteric glands, (4) in the glands of the liver or 
the liver itself and (5) in the generative organs and udder. It 
frequently happens that the pleura or the peritoneum is thickly 
sprinkled with tubercular nodules. The extent of the disease that 
may exist and have the animals appear to be in perfect health 
depends upon the location of the lesions. Frequently large masses 
of tubercular deposits are found in apparently healthy animals. As 
a rule these are not in vital organs. Again, cattle run down 
rapidly and may die of the disease before the lesions attain great 
size becaise they are in and destroying an organ that is very essen- 
tial to the life of the individual. 
*Moore, V. A. A report on bovine tuberculosis. N. Y. Dept. Agr. 
Annual Report, 1903. 
* Millie D. gave a reaction in October, 1901, and in June, 1902. She failed 
to react at six subsequent tests beginning with December, 1902. She con- 
tained living germs of tuberculosis in 1905, page 55. 
