Heredity 145 



The fact is, we are returning to an appreciation 

 of the subtlety of Darwin's concept of selection. It 

 is not one process, but many — lethal and reproduc- 

 tive, for instance ; it operates in relation to an intri- 

 cate web of life, and a Shibboleth may have survival 

 value ; there has been an evolution of sieves as well as 

 of the material to be sifted. As we have seen, the 

 struggle for existence, in the course of which selection 

 occurs, includes not only competitive but symbiotic, 

 not only egoistic but altruistic reactions, and both 

 pay! 



§16. As Regards Heredity. 



In two books recently published on evolution we find 

 two extraordinarily divergent statements in regard 

 to heredity. In one of them Professor Lotsy says : "Of 

 heredity we know nothing." In the other, Professor 

 T. H. Morgan says : "The problem of heredity may 

 be said to be solved." What is the meaning of this 

 discrepancy? Mainly this: that the first writer was 

 trying to think of the almost unthinkable way in 

 which all the manif oldness of a well-endowed creature 

 is somehow telescoped-down into a microscopic im- 

 plicit individuality — the germ-cell. An egg-cell is 

 considered large if it is the size of a pin's head; a 

 sperm-cell is often only tt 0W0- of the size of the egg- 

 cell. Darwin spoke of the brain of the ant as the most 

 marvellous atom of matter in the world, but the egg- 

 cell of the ant is more wonderful still. For it implies 

 the whole ant, brain included. We cannot picture to 

 ourselves either the impliciting or the expliciting of 



