Prophylaxis 637 



it always produces some fever, slight local swellings, and 

 malaise. 



Wyssokowitsch and Zabolotny,* whose studies have al- 

 ready been quoted, used 96 monkeys in the study of the value 

 of the "plague serums," and found that when treatment is 

 begun within two days from the time of inoculation the 

 animals can be saved, even though symptoms of the disease 

 are marked. After the second day the treatment cannot 

 be relied upon. The dose necessary was 20 c.c. of a serum 

 having a potency of i : 10. If too little serum was given, 

 the course of the disease was retarded and the animal im- 

 proved for a time, then suffered a relapse, and died in from 

 thirteen to seventeen days. The serum also produced 

 immunity, but of only ten to fourteen days' duration. 

 Immunity lasting three weeks was conferred by inoculating 

 a monkey with an agar-agar culture heated to 60 C. If 

 too large a dose of such a culture was given, however, the 

 animal was enfeebled and remained susceptible. 



Of Yersin's serum, which is prepared by immunizing 

 horses against the toxins and cultures of the bacillus in the 

 usual manner, 5 c.c. doses have been found to confer an im- 

 munity lasting for about a fortnight. Larger doses confer 

 a longer immunity. For the treatment of the developed 

 disease in man, doses of 50 and even 100-200 c.c. seem 

 necessary to produce the desired effect. 



* Loc. cit. 



