506 DISEASE IN WILD MAMMALS AND BIRDS 
from the mucosa through the intestinal wall by following 
lymphatic channels and that irregular contractions of the 
musculature squeeze the exudate outward under the 
serosa. Other observers think that the bacilli are car- 
ried via the lymphatics to the superitoneal tissue, 
there starting the tubercle. The truth of the matter will 
probably be that both methods are operative although we 
have seen more cases suggestive of the second than of the 
first explanation. When these peritoneal nodules are 
numerous and prominent, mucosal ulcers are uncommon 
and vice versa. 
The second form is the ulcerative, flat ragged or 
crateriform defect situated in a diffusely thickened wall. 
This was well illustrated in cases of pulmonary infection 
in doves and guans, suggesting reinfection of the gut 
tract from swallowed tubercle bacilli or a backward 
development of the disease after the lungs were 
nearly solid. 
The third form of tuberculous enteritis is quite inter- 
esting and striking. It is best seen in the duodenal loop 
but may occur anywhere. Diffuse thickening of the 
enteric wall is noted, and when palpation is practiced a 
resilient but leathery sensation is obtained. Careful 
inspection reveals the mucous surface to be velvety, a con- 
dition due to a swelling, that is widening, of the villi which 
retain their erect position and, when washed in flowing 
water, will be seen to move like a field of grain in a 
breeze. The serosa may be, usually is, negative. Studied 
microscopically the peculiarity of this form is in the 
development of tubercles and diffuse cellular exudation in 
the ^dllus stalk, sometimes extending into the submucosa 
also. Round cell masses like lymph follicles are some- 
times prominent. This form is not associated with any 
peculiar organic distribution so far as my studies go. 
Passeres. The peculiarity of this order seems to be in 
the predominance of the pulmonary route as origin of 
tuberculosis. Perhaps in no other order has there been 
