26o THE EVOLUTION OE SEX. 



SUMMARY. 



I. In most of the emotions, and in the simpler intellectual processes, there is 

 common ground between animals and men. This is especially true of the 

 emotions associated with sex and reproduction. 



II. The love of mates has its roots in physical sexual attraction, but has been 

 gradually enhanced by psychical sympathies. 



III. The means of sexual attraction rise from the crude and physical to the 

 subtle and psychical, with the growth of love. 



IV. The intellectual and emotional differences between the sexes are 

 correlated with the deep-seated constitutional differences. Males and females 

 are complementary, each higher in its own way. 



V. The love for offspring has grown as gradually as the love for mates. 

 Even lactation and maternal care may be in part egoistic. Except in a few 

 precociously tender animals, genuine love for offspring is only emphatic in birds 

 and mammals, where the reproductive sacrifice of the mother has also been 

 increased. 



VI. The cuckoo illustrates the evolution of a criminal habit, mainly due to 

 constitutional conditions. 



VII. Egoism and altruism have their roots in the primary hunger and love, 

 or nutritive and reproductive activities. The divergent streams of emotion and 

 activity have a common origin, subtly mingle at various turning-points, and 

 ought to blend more and more in one. 



LITERATURE. 



See works on Sexual Selection cited at Chapter I. 



Eimer, G. H. T. — Die Entstehung der Arten auf Grund von Vererben 



Erworbener Eigenschaften nach den Gesetzen Organischen Wachsens. 



Jena, 1888. 

 Buchner, L. — Liebe und Leibesleben in der Thierwelt. Berlin, 1879. 

 Rolph, W. H — Op. cit. 

 Romanes, G.J.-— Animal Intelligence. Internat. Sci. Series. Fourth edition, 



1S86; and Mental Evolution in Animals, by the same. 

 Thomson, J. A. — A Theory of the Parasitic Habit of the Cuckoo. Proc. Roy. 



Phys. Soc. Edin. 1888. 

 See also Carus Sterne's most admirable of general natural history books — 



YVerden und Vergehen. Third edition. Berlin, 1886. 

 Ploss. — Das Weib in der Natur und Volkerkunde. Second edition. Leipzig, 



1887. 

 Mantegazza, P. — Die Physiologie der Liebe ; Die Hygiene der Liebe ; 



Anthropologisch-Kulturhistorische Studien iiber die Geschlechtsverhaltnisse 



des Menschen. Jena. 



