DOUBTFUL PHENOMENA OF HEREDITY 39 1 



fection from without cannot be conclusively disproved in any 

 individual instance, I am inclined to believe that they have been 

 too cautious in their conclusions, of which only a negative proof 

 is furnished by either factor. For neither of these in the least 

 proves that infection of the germ does 7iot take place : from a 

 more general, biological point of view, indeed, it seems to be far 

 more probable that it does. 



It will, I think, at any rate be conceded that a 'constitu- 

 tional ' disease cannot be taken as a proof that the processes of 

 heredity are therein concerned until we can determine whether 

 we are actually dealing with heredity, — i.e., the transmission of 

 a constitution, — and not only with a transference of microbes; 

 and the main object of this section was to make this clear. 

 But at the same time I have stated my reasons for using so 

 few facts from the domain of pathology in support of my 

 theory. 



