GENETICS AND ETHICS 471 



But leaving out of account all forms which 

 are so monstrous that they are incapable of 

 reaching maturity we find that there are left 

 many variations in the size and vigor of the 

 body as a whole, as well as of its parts; many 

 variations in the more or less perfect correla- 

 tion of these parts with one another, which 

 were determined by the conditions of develop- 

 ment rather than by heredity. In a given germ 

 cell there is the potency of any kind of organ- 

 ism that could develop from that cell under 

 any kind of conditions. The potencies of de- 

 velopment are much greater than the actuali- 

 ties. Anything which could possibly appear 

 in the course of development is potential in 

 heredity and under given conditions of en- 

 vironment is predetermined. Since the en- 

 vironment cannot be all things at once many 

 hereditary possibilities must remain latent or 

 undeveloped. Consequently the results of de- 

 velopment are not determined by heredity 

 alone but also by extrinsic causes. Things 

 cannot be predetermined in heredity which are 

 not also predetermined in environment. 



Of all animals I suppose that man enjoys 



