THE NATURAL 



CHAPTER III 



SCALE OF SEXES 



Asexual reproduction. Formation of the animal colony. 

 Limits of asexual reproduction. Coupling. 

 Birth of the sexes. Hermaphrodism and partheno- 

 genesis. Chemical fecundation. Universality of par- 

 thenogenesis. 



THE primitive mode of reproduction is asexual, or what 

 one will so consider provisorily, in comparison with more 

 complex mechanism. In the first living forms there are 

 neither sexual organs nor differentiated sexual elements. 

 The animal reproduces itself by scissiparity or by bud- 

 ding; the individual divides itself in two parts, or a 

 protuberance develops, forms a new being and then 

 separates. 



Scissiparity is an inexact term, for the division is 

 transversal, and the two parts far from equal; it occurs 

 in protozoaires, and further in worms, star-fish and polyps. 

 Budding is common to protozoaires, infusoria, ccelen- 

 terata, to fresh-water polyps and to nearly all vegetables. 

 A third primitive mode, sporulation, consists in the pro- 

 duction inside the organism of particular cells, spores, 

 which separate and become individuals; this occurs in 

 protozoaires, as well as in ferns, algae and mushrooms. 



The first two modes, division and budding, serve also 



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