BACILLUS OF TUBERCULOSIS. 275 
death at the end of several weeks or months. Subcuta- 
neous inoculations are less effective, and in small doses 
do not always kill. Intravenous and intraperitoneal 
injections usually produce general tuberculosis and 
death at the end of a few weeks. The tubercles in 
rabbits are smaller, as a rule, and the spleen and liver 
not so much enlarged as in guinea-pigs, but the kidneys 
not infrequently contain nodules of the size of a pea. 
Of other susceptible animals, field-mice and cats 
are readily infected by artificial inoculations of tuber- 
culous material; rats, white mice, and dogs only 
when very large doses are given. All these animals 
present the anatomical lesions of miliary tuberculosis. 
Bollinger has produced intestinal tuberculosis in calves 
by inoculating them with material taken from a tuber- 
culous man. Canaries are also susceptible to inocula- 
tions of the tubercle bacillus; but not sparrows. Cold- 
blooded animals of various kinds, according to the 
experiments of Koch, are immune, unless, as recently 
demonstrated, the bacilli are first slowly accustomed 
to growth at low temperatures. owls and pigeons 
are only slightly susceptible to the bacillus derived 
from man. Among the larger birds, parrots alone 
would seem to be clearly susceptible. 
Beside the artificial modes of infection already re- 
ferred to, tuberculosis may be caused in animals by 
feeding them with tuberculous material. In this case 
evidence of infection is usually shown in the mesenteric 
glands before the intestinal walls are affected. Zagari 
records some experiments in which tubercle bacilli fed 
to dogs (one of the less susceptible animals) were ab- 
sorbed by the mucous membranes of the intestines, and 
thus reached the internal organs without producing any 
