THE PERITONEUM 261 
trauma and intestinal perforations by sharp objects. 
Ungulata frequently suffer abdominal injuries in fighting, 
as do rodents. Peritonitis sometimes supervenes even in 
the absence of penetrating wounds, probably by reason of 
damage to the intestine whereby its permeability is 
increased. Pointed objects are frequently swallowed by 
animals and perforation occurs. The danger of feeding 
split bone to carnivores is well known; some years ago 
we lost two tigers and a lion in this manner. 
Ileus, in one of the several forms, has been an 
occasional cause of peritonitis in primates and migu- 
lates. The extension of purulent inflammation, abscesses 
and the like is easy to understand, but we have seen 
several cases of apparent extension from enteritis with- 
out perforation. The reason for this is probably in the 
kind of enteritis. Monkeys with amoebiasis and gallina- 
ceous birds with enterohepatitis have supplied most of 
the cases, these infestations of the gut wall being deep 
and spreading so that a chance is afforded to penetrate 
the serosa along blood and lymph vessels. One case in a 
deer seemed to originate from a simple catarrhal colitis ; 
trichocephalus in the colon may have helped. Parasites 
are not ver^^ potent in causing an acute peritonitis, but 
aggravate the action of other agents. Septicemic states 
are at the bottom of 24 per cent, of our cases of peri- 
tonitis. This is particularly true of birds, it being 
recognized that their acute general infections frequently 
have such an effect, but the primates and carnivores also 
have a vulnerable peritoneum when septicemia exists. 
The principal outstanding visceral lesions in the mam- 
malian cases is pneumonia; in birds it is cholera and 
plague. The rupture of eggs in birds lays the foundation 
of a peritonitis, while bacteria from the oviduct or cloaca 
complete the process. Chronic peritonitis is not common. 
It is usually due to parasites or to tuberculosis. There 
