104 Disease and Immunity 



not seriously to injure the vine. In fighting this 

 light attack the vine would build up its powers of 

 resistance so that later it would be able to resist 

 a more severe attack. 



Resistance to disease is an inheritable thing 

 which passes from parent to offspring. But an 

 offspring cannot inherit from a parent something 

 which the parent did not have. We know that 

 a parent can build up his general powers by 

 general exercise, and that he can build up his 

 powers of resisting a particular disease by fight- 

 ing that disease or some modified form of it. 

 Briefly, the offspring inherits the identical thing 

 which the parent acquires by his effort and exer- 

 tion, and there is not a particle of evidence of 

 any kind that any animal or plant can come into 

 possession of powers of resisting disease in any 

 other way than by direct acquirement or in- 

 heritance of such acquirement. Natural im- 

 munity is nothing else than an inherited power 

 coming from an ancestor who acquired that 

 power by effort and exertion. 



