xu 



Contents. 



Elimination and selection 



Modes of natural elimination illustrated 



Protective resemblance and mimicry 



Selection proper illustrated . . 



The eflfects of natural selection . . 



Isolation or segregation 



Its modes, geographical, preferential and physiological 



Its effects . . 



Utility of specific characters 



Variations in the intensity of the struggle for existence 



Convergence of characters 



Modes of adaptation ; Progress 



Evolution and Revolution 



CHAPTER V. 



HEREDITY AND THE ORIGIN OF VARIATIONS, 



Heredity in the protozoa 



Eegeneration of lost parts 



Sexual reproduction and heredity 



The problem of hen and eg^ . . 



Reproductive continuity 



Pangenesis 



Modified pangenesis . . . . . . . . 



Continuity of germ-plasm 



Cellular continuity with differentiation 



The inheritance or non-inheritance of acquired characters 



Origin of variations on the latter view 



Hypothesis of organic combination 



The extrusion of the second polar cell 



The protozoan origin of variations 



How can the body influence the germ ? 



Is there sufficient evidence that it does ? 



Summary and conclusion 



CHAPTER VI. 



ORGANIC EVOLUTION, 



The diversity of animal life 



The evolution theory 



Natural selection ; not to be used as a magic formula 



Panmixia and disuse 



Sexual selection or preferential mating 



Use and disuse 



The nature of variations . . 



The inheritance of variations 



The origin of variations . . 



Summary and conclusion 



