174 DR. H. B. FANTHAM 



research in this branch of knowledo^e termed biometry. 

 However, Galton's law merely expresses the average re 

 snlts which may be anticipated from the interbreeding 

 of a large population, in which hybridisation probably 

 plays a very small part, and so it is not necessarily con- 

 tradictory of Mendelian results. In the words of Profes- 

 sor Karl Pearson: "It is the heavy weight of this medi- 

 oci-e ancestry which causes the son of an exceptional 

 father to regress towards the general population mean ; 

 it is the balance of this sturdy commonplaceness which 

 enables the son of a degenerate father to escape the 

 whole burden of the paternal ill. Among mankind we 

 trust largely for our exceptional men to extreme varia- 

 tions occurring among the commonplace, but .... if we 

 could remove the drag of the mediocre element in an- 

 cestry, were it only for a few generations, we should 

 sensibly eliminate regression or create a stock of excep- 

 tional men." 



That regression can occur in Nature is shown, for 

 example, in the development of Ascidians or sea-squirts. 



Mechanistic theories of evolution have been put for- 

 ward. Of these we may briefly notice a few of the con- 

 ceptions of bio-mechanics. W. Roux considers the tissues 

 and cells of the concrete organism. He is essentially con- 

 cerned with embryology, as is also O. Hertwig. They 

 attribute difl'erentiation of the organism to the mutual 

 attraction of the cells of the early embryo. Herbst at- 

 tributes these attractions to chemical action. Roux 

 thinks that there is a struggle between the parts of the 

 organism for the economic use of food and space. He 

 states tliat many structures are due to functional stimu- 

 lation. Roux's l!yi>ot]iesis is one of heredity, and he 

 recognises the inheritance of acquired characters. The 

 famous experimental physiologist, Jacques Loeb, has 

 similar views, and considers that the problem of fertilisa- 

 tion is really physico-chemical in nature, the development 

 of the egg being regarded as a chemical i)rocess which 

 depends mainlv on (>xidati<m. 



