AND ITS RELATION TO ANIMAL LIFE 71 



could not be made to take the disease during 

 a period of two to four months, although during 

 that period they had from 200 to 300 cubic 

 centimetres of virulent blood injected under 

 the skin ; and when it is remembered that one 

 drop of virulent blood is more than enough to 

 give an animal the disease, then these animals 

 had enough to give them the disease thousands 

 of times ; yet it had no effect on them, either 

 as far as the eye could see or the thermometer 

 indicate. 



These animals were in various bile stations, 

 and any one wishing to learn how to use the 

 hypodermic syringe was permitted to experi- 

 ment on them, yet they never suffered from 

 the constant inoculation. Hence we can only 

 conclude that they were immune to an unlim- 

 ited extent. 



Again, doctors and nurses in consumptive 

 hospitals must, in the course of twelve months, 

 take in by the mouth and nose myriads of 

 tubercular bacilli, yet the large majority of 

 them never take the disease. 



So that the blood of these people has plenty 

 of killing power, and it is the same in other 

 diseases. 



