SECTION VII 
THE ALIMENTARY TRACT, PART 4. 
THE PERITONEUM 
This visceral envelope is principally important 
because of the fatal character of its acute inflammations. 
In man peritonitis of acute origin and type is commonly 
secondary to a focus of progressive inflammation in some 
abdominal organ and usually speaks for the virulence of 
the primary disease and for the low resistance of the 
serous membrane. Because of this vulnerability, greater 
foresight is attempted to prevent the extension of acute 
intra-abdominal inflammations and under operative con- 
ditions punctilious care is used to avoid contamination of 
the general peritoneal cavity. Involvement of the peri- 
toneum in septicemic states is relatively uncommon in 
man, but seemingly more frequent in the lower mammal. 
This surface seems more resistant to infection at oper- 
ation in the lower animals since post-operative peritonitis 
after castration and experimental procedure is certainly 
infrequent ; our data will permit no percentage figures of 
vulnerability under such conditions. Judging, however, 
from the number of times at which the diagnosis of acute 
peritonitis has been made, the lower animal has a 
decidedly low percentage resistance although its patho- 
logical states are primary or secondary to conditions 
unusual in man. Among the 5365 autopsies acute peri- 
tonitis appears in the diagnoses 137 times or 2.4 per cent. ; 
mammals, 57 or 3 per cent. ; birds, 80 or 2.3 per cent. 
The exact causes are usually obvious, practically 
always so in human medicine, but a number of cases 
escape adequate explanation. From a practical stand- 
point two origins are important to zoological collections, 
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