42 EVOLUTION, SOCIAL AND ORGANIC 



works — at least among living things, 

 (biology) — has made the general theory im- 

 pregnable. 



Before proceeding to that specific theory let 

 us clearly understand that evolution has 

 ceased to be a theory merely, it is also a well 

 established fact. Anyone who denies this has 

 no part or lot in the intellectual life of the last 

 half century. Such a one, as Professor 

 Giddings recently said, ''inhabits a world of 

 intellectual shades. He cannot grasp the 

 earthly interests of the twentieth century." 



Every science in the biological hierarchy has 

 contributed its quota to the establishment of 

 the theory of evolution, and that theory in 

 return has, in one department after another, 

 produced order and system where before 

 nothing existed but a conglomerate mass of 

 apparently unrelated facts. So thoroughly 

 has the theory impregnated every branch of 

 science that an intelligent dentist must be an 

 evolutionist. 



The chief honors fall to the two sciences 

 Ontogeny and Phylogeny. Ontogeny deals 

 with the history of the germ from its be- 

 ginnning as an egg to its full fruition as a fully 

 developed individual or as Haeckel defines it, 

 "the history of the evolution of individual 

 human organisms." Phylogeny is defined by 



