278 ORIENTAL PLAGUE chap, ix 



i.e. on successive days, it loses none of its protective 

 efficacy. Tested by culture this so heated filtrate is found 

 reliably sterile. It can in this form easily be preserved in 

 sealed tubes. 



A large number of rats were tested with twice-heated 

 filtrate of organ prophylactic, and it was ascertained that, 

 supposing the dose of the mother-substance is 12 to 16 

 milligrammes, the dose per rat of the filtrate would amount 

 to about one-third more, i.e. would correspond to 20 to 25 

 milligrammes of the entire prophylactic. 



