xvi] VIBRIO AND SPIRILLUM 431 



The fatal dose — producing death in or within twenty-four 

 hours — differs according to the initial virulence and the size 

 of the animal. The fatal dose of living vibrios from an 

 Agar culture is always a little smaller than if the dose to be 

 injected is first sterilised, either by boiling or, as I generally 

 do, by heating it to 70° C. for five or ten minutes, or, as was 

 done by R. Pfeiffer, by killing the vibrios by chloroform. 



Fig. 178. — Film Si'ECniEN of ax Agar Cl'lture op" Cholera ViliRlos, a few 

 Weeks old, showing numerous long Si'Irilla. 



About 400. 



On post-mortem examination the peritoneum is found 

 intensely inflamed : hyperremia of the serous covering and 

 of the wall of the intestine, sanguineous copious fluid or 

 slightly viscid peritoneal exudation, turbid by being densely 

 crowded with the living motile vibrios (if the culture injected 

 was not previously sterilised), flocculi of lymph on the 

 omentum, on the intestine, and particularly the surfaces of 



