74 PLANT DISEASE 



At the same time it was not every bile that 

 would render animals immune. 



It had to be what was considered a healthy 

 bile, and even that was not always successful. 



In fact, bile taken out of one jar, when hypo- 

 dermically injected would render one lot of 

 animals immune and would have no effect on 

 others. Now no one will doubt that bile 

 would contain more or less iron and proteids, 

 and that the efficacy of the bile would vary as 

 the iron, and consequently the proteids con- 

 tained therein. 



One can also understand that the iron and 

 proteids would vary in the blood of different 

 animals, so that the efficacy of the bile inocu- 

 lation would vary as the iron and proteids in 

 the bile and in the blood of the animals inocu- 

 lated. 



