32 BIOLOGICAL SOCIETY OF WASHINGTON. 



terms as the doctrine of natural selection or survival of the 

 fittest among the organic units constituting the stirp, to de- 

 termine which shall become manifest in the offspring and which 

 shall lie latent to reappear or not in later generations. As the 

 stirp contains organic units that have lain latent in previous 

 generations and may become patent in the generation in ques- 

 tion, the theor}- accounts for reversion, atavism, and the whole 

 train of facts in heredity that have so long puzzled the scientific 

 investigator. We are at present onl}- concerned with so much 

 of it as relates to the transmission of acquired characters. The 

 following passage expresses his views on this point : " We have 

 thus far dealt with three agents — (i) the stirp, which is an or- 

 ganized aggregate of a host of germs ; (2) the personal struc- 

 ture, developed out of a small portion of these germs ; and (3) 

 the sexual elements, generated by the residuum of the stirp. 

 The cases before us are those which are supposed to prove that 

 2 reacts on 3 — that is, the personal structijre upon the .sexual 

 elements. The first and largest class of these cases refer to 

 adaptivity of race. It is said that the structure of an animal 

 changes when he is placed under changed conditions ; that his 

 offspring inherit some of his change ; and that they vary still 

 further on their own account, in the same direction, and so on 

 through successive generations, until a notable change in the 

 congenital characteristics of the race has been effected. Hence 

 it is<:oncluded that a change in the personal structure has re- 

 acted on the .sexual elements. For my part, I object to so 

 general a conclusion." And he proceeds to elaborate his 

 reasons for such objection. Passing over these for want of 

 time I will conclude this exposition of Galton's views by quot- 

 ing the following passage : 



"The conclu.sion to be drawn from the foregoing arguments 

 is, that we might almost reserve our belief that the structural 



