26 THE EVOLUTION OF SEX. 



SUMMARY. 



L, II., III. — A broader basis must be sought from which to understand the 

 differences between the sexes. A general survey shows that the males are 

 more active in habit, the females more passive; that the males tend to be 

 larger and to live longer. 



IV. — The close association of secondary sexual characters with the repro- 

 ductive function is shown in the period or in the periodicity of their develop- 

 ment, in the effects of castration, in the peculiarities of aged females, &c. Richer 

 pigmentation, and other male characteristics, are to be interpreted as expressions 

 of the katabolic predominance in the constitution of males, as opposed to the 

 anabolic preponderance of the females. 



V. — Sexual selection, as an explanation of secondary sexual characters, is 

 limited, by being teleological rather than serological, does not account for origins 

 nor incipient stages, postulates subtle aesthetic sensitiveness, and is beset by 

 numerous minor difficulties. Vet the opposed positions of Darwin and Wallace 

 both emphasize indubitable facts; while the criticisms of Mivart, the theory of 

 Brooks, and the suggestions of Rolph, Mantegazza, and others, lead on toward 

 a deeper analysis. The general conclusion reached recognizes sexual selection 

 (so far with Darwin) as a minor accelerant, natural selection (so far with Wallace) 

 as a retarding "brake," on the differentiation of sexual characters, which essen- 

 tially find a constitutional or organizmal origin in the katabolic or anabolic 

 diathesis which preponderates in males and females respectively. 



LITERATURE. 



Brooks, Darwin, Mivart, Wallace. — As before. 



Eimer,G. H.T. — Die Enstehung derArten aufGrund vonVererben erworbener 

 Eigenschaften, nach den Gesetzen organischen Wachsens. Jena, 1888. 



Geddes, P. — Articles "Reproduction," "Sex," "Variation and Selection," 

 Encylc. Brit. Also on the "Theory- of Growth, Reproduction, Sex, and 

 Heredity," Proc. Roy. Soc. Edin. 1885-6. 



Rolph, W. H. — Biologische Probleme. Leipzig, 1884. 



Weismann, A. — Studies in the Theory of Descent (Meldola's Translation). 

 London, 1S80-82. 



Wallace, A. R. — Darwinism: An Exposition of the Theory of Natural Selec- 

 tion, with Some of its Applications. [No. T15 and No. 116 of The Humboldt 

 Library .] 



