TOXINS AND ANTITOXINS. 39 



2. Make inoculations of Spirillum cholerse asiaticse, 

 Spirillum Metchnikovi, and Spirillum of Finkier and 

 Prior on, 



(a) agar tubes (slope); 



(b) gelatine tubes (stab); 



(c) peptone tubes. 



Toxins and Antitoxins. (Class Demonstration). 

 (rt) A medium sized guinea pig (about 400 grammes) 

 is inoculated subcutaneously with .5 cc. of a 24 hours 

 broth culture Bacillus diphtheriae (virulent). The ani- 

 mal usually dies in from 24 to 36 hours. 



Broth cultures of Bacillu sdiphtherise are filtered 

 through porcelain (Chamberland's candles), to obtain 

 the toxins free from the bacilli. Guinea pigs are inocu- 

 lated and the maximum fatal dose learned and the toxin 

 is then standardized. (.01 cc. of standard toxin kills a 

 medium sized pig in 3^ days). 



(b) A guinea pig is inoculated with the minimum 

 dose of the toxin (death in 3 days). 



(c) A guinea pig is inoculated with 100 times the 

 minimum fatal dose, plus one unit of some standard 

 antitoxin. The animal recovers. 



(d) A guinea pig is inoculated with 100 times the 

 minimum fatal dose. 15 minutes afterward one unit of 

 antitoxin is inoculated. The animal dies. 



