BUBONIC PLAGUE. 241 



desiccation kills the bacillus. In sterilised water the 

 bacillus has remained alive for fifteen days at room- 

 temperature. 



According to Yersin, flies can serve as propagators of the 

 disease. The injection of liquid cultures into white mice, 

 guinea-pigs, rabbits, and rats, produces plague symptoms, 

 and the animals die in two to five days. An injection of 

 O'l of a cubic centimetre of an emulsion of a recent culture 

 of plague will generally kill a white mouse of ordinary size 

 in one to three days. When introduced into the gastric 

 canal, they act much more slowly. A quarter of a centi- 

 gramme of dried plague toxin may be considered to be a 

 fatal dose to a mouse, half a centigramme is quickly fatal, 

 and one centigramme is rapidly so, generally in about 

 twelve hours. 



The bacilli are found in the viscera and lymphatic 

 ganglia of inoculated animals, but are not very numerous 

 in the blood. 



Antitoxin Treatment. — Since the time that the bacillus 

 has been isolated attempts have been made to adopt the 

 serum treatment in cases of plague. Yersin has succeeded 

 in immunising horses, and thus obtaining a serum of which 

 one-tenth of a centimetre protects white mice against an 

 otherwise fatal dose of the toxin or of the culture of the 

 bacillus. This serum he has since used on plague patients 

 in China and at Bombay with very good effect ; but in order 

 to obtain the best results, it would appear necessary that 

 the disease should be taken in its earliest stages. The 

 serum also possesses great curative properties. Haffkine, 

 too, has been experimenting at Bombay, but, so far as can 

 be gathered, his efforts have been chiefly aimed at pro- 

 tective measures. His method consists in the injection of 

 killed cultures. He states in his report to the Bombay 

 Corporation ' that he inoculated himself in the flank with 



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