116 DISEASE IN WILD MAMMALS AND BIRDS 
the chords. Since the nodal tissue of birds is not so 
sharply delimited by some sort of capsule, it is but 
natural that the hyperplasia should be diffuse; in the 
intestinal wall it may extend laterally twice or thrice the 
width of the normal follicle. Necrosis, unless the disease 
be mycotic, tuberculous or parasitic, is uncommon. 
It may be well to discuss for a space the reaction to 
infection of the thoracic and intestinal lymphatics in 
mammals. The amount of lymphadenoid tissue in the 
mediastinum is very great in some mammals, notably the 
Ungulates, while in others, the Rodents and Primates, for 
example, it is not so plentiful. Nevertheless the gross 
and minute changes are usually of the edemato-exudative 
type — large, pink, soft, moist glands. In the abdomen, 
on the other hand, one usually finds well outlined, firm, 
yellow nodes in the mesentery and behind the peritoneum. 
This is not only to be discovered in various chronic 
diseases of the intestine but even in acute, so-called toxic 
enteritis seen in caniivores from food poisonings. One 
must therefore ask if the local nodes abundant in the 
intestinal mucosa do not take up the poisons which cause 
the acute hyperplasia and are in turn backed up by the 
stalk glands. Even in so acute and overwhelming a 
disease of the intestine as hog cholera (which we have not 
had here) the glands retain their general structure, 
although hemorrhagic, while in late stages they become 
firm, sharply outlined and pigmented. In birds there may 
be swelling of the omental bursa?, but as there are no 
lymph glands no masses are found. 
The response on the part of the lymphatic tissues as a 
system, or some large section of this system, is shown in 
the following figures. It is our practice to include in the 
diagnosis general acute or chronic lymphadenitis or 
inflammation of a large drainage area. Acute changes 
have been mentioned 103 times, in which the important 
orders are represented as follows : Primates 21, Car- 
nivora 46, Ungulata 15, Rodentia 3, Marsupialia 13, 
