344 BACTERIOLOGY. 



The animal usually dies after remaining in this con- 

 dition for a few hours. 



At autopsy the small intestine is found to be deeply 

 injected and filled with a flocculent, colorless fluid. 

 The stomach and intestines do not contain solid masses, 

 but fluid ; when diarrhoea does not occur, firm scybala 

 may be expected in the rectum. Both by microscopic 

 examination and by culture methods, comma bacilli are 

 found to be present in the small intestine in practically 

 pure culture. 



More recently Pfeiffer 1 has determined that essentially 

 similar constitutional effects may be produced in guinea- 

 pigs by the intra-peritoneal injection of relatively large 

 numbers of this organism. His plan is to scrape from 

 the surface of a fresh culture on agar-agar as much of 

 the growth as can be held upon a moderate-sized wire 

 loop. This is then finely divided in 1 c.c. of bouillon 

 and, by means of a hypodermic syringe, is injected 

 directly into the peritoneal cavity. When virulent cul- 

 tures have been used this is quickly followed by a fall 

 in the temperature of the animal ; this is gradual and 

 continuous until death ensues, which is usually in from 

 eighteen to twenty-four hours after the operation, though 

 exceptionally cases do occur in which the animal recov- 

 ers, even after having exhibited marked symptoms of 

 most profound toxaemia. 



In pursuance of his studies upon this disease, Pfeiffer 2 

 has demonstrated that it is possible to render an animal 

 tolerant or immune to the poisonous properties of this 

 organism by repeated injections of non-fatal doses of 

 dead cultures (cultures that have been killed by the 



1 Zeitschrift fur Hygiene, Bd. xi. and xiv. 



2 Zeit. fur Hyg. u. Infections Krankheiten, Bd. ix., Heft. i. 



