xii HEREDITY AND SELECTION IN SOCIOLOGY 



PAGES 



3. Importance of isolation in the evolution of species — How 



isolation effects the development of variations — Co-operation of 

 isolation and natural selection — Amixis does not necessarily 

 produce variation — The sexual " isolation " of Romanes. 



4. The action of selection on the origin of species — The life- 



history of species — Death not a necessity inherent to organic 

 life — Immortality of the Protozoa and of the germ-plasm of the 

 Metazoa — No parallel between ontogeny and phylogeny — 

 Death not a constitutional necessity for species — Extinction of 

 species is due to inability to effect sufficiently rapid readaptation 

 — Case of the TrUobites — Extinction may also result from direct 

 inferiority^ExtiQction of inferior human races — ^Extinction is 

 always due to changes in the environing conditions - - 129-156 



CHAPTER X 

 Pabents and OrrsPBiNG 

 Elimination of ancestral ids from the germ-plasm by the expulsion 

 of the polar bodies from the egg, and the repeated division of the 

 sperm-ceU before maturation — Persistence of former id-com- 

 plexes in the human germ-plasm— Significance of the reducing 

 divisions for the theory of descent — ^Multiplication of variations 

 by amphimixis — Distinctness of male and female elements in the 

 nucleus of fertihsed ovum throughout the embryogeny — ^Pre- 

 ponderance of homodynamic over heterodynamic determinants 

 — Specific determinants of the species always homod3fnamic — 

 Large number of individual variations rendered possible by neo- 

 taxis of the germ-plasm — Number of variations dependent on 

 the number of chromosomes - - 157-164 



Appendices - - 165-173 



PAET II 

 SOCIAL PATHOLOGY 



CHAPTER I 

 Suicide as a Social Factok 

 1. Innate tendency of organic Ufe counteracted by the action of 

 selection — Suicide as a social factor — Individualist theories of 

 society — Increase in the rate of suicide since the middle of the 

 nineteenth century — The increase of suicide is not due to an 

 increase of insanity — Suicide and heredity — ^Imitation as a 



