CONTENTS 



CHAPTER PACK 



I. THE SUBJECT OF AN IDEA n 



Love's general psychology. Love according to natural 

 laws. Sexual selection. Man's place in Nature. 

 Identity of human and animal psychology. The 

 animal nature of love. 



II. THE AIM OF LIFE 17 



The importance of the sexual act. Its ineluctable 

 character. Animals who live only to reproduce them- 

 selves. The strife for love, and for death. Females 

 fecundated at the very instant of birth. The main- 

 tenance of life. 



III. SCALE OF SEXES 22 



Asexual reproduction. Formation of the animal col- 

 ony. Limits of asexual reproduction. Coupling. 

 Birth of the sexes. Hermaphrodism and partheno- 

 genesis. Chemical fecundation. Universality of par- 

 thenogenesis. 



IV. SEXUAL DIMORPHISM 31 



1. Invertebrates: formation of the male. Primitiv- 

 ity of the female. Minuscule males: the bonellie. 

 Regression of the male into the male organ: the 

 cirripedes. Generality of sexual dimorphism. Su- 

 periority of the female in most insect species. Excep- 

 tions. Numeric dimorphism. Female hymenoptera. 

 Multiplicity of her activities. Male's purely sexual 

 role. Dimorphism of ants and termites. Grasshoppers 

 and crickets. Spiders. Coleoptera. Glow-worm. 

 Cochineal's strange dimorphism. 



V. SEXUAL DIMORPHISM 43 



2. Vertebrates: Unnoticeable in fish, saurians, reptiles. 

 The bird world. Dimorphism favourable to males: 



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