PRIMARY CHARACTERISTICS 7 



some cells exhibit a feminine tendency (anabolism), Defcermina- 

 and others a masculine (katabolism). The conclusion 

 of Geddes and Thomson is that u male and female are 

 the results and expressions of relatively predominant 

 katabolism and anabolism respectively". 



This conclusion may be, and probably is, perfectly 

 true, but it does not explain how the differentiations 

 came about. It is a statement of effect, not of cause. 



In the human subject the sexes are definitely 

 differentiated : the species is dioecious. In certain of 

 the lower animals, such as various species of worms, 

 the sexual condition is monoecious ; that is to say, each 

 creature has the genital organs of both sexes, and may 

 be capable of fertilizing others of the same species and 

 of being fertilized. The term commonly employed for 

 this condition is ' Hermaphroditism •*• In bees there 

 are three variations — perfect females, imperfect females 

 and males. Further, in certain of the insects, such as 

 the silk-worm moth, the development of an adult from 

 the unfertilized ovum has been observed to occur 

 occasionally. This is known as * Parthenogenesis \ 



It may be laid down, then, that generally speaking 

 the higher the species stands in the scale of evolution, 

 the greater is the differentiation between the primary 

 characteristics of the two sexes. 



The various theories propounded concerning the Theories 

 origin of sex emanate from three different points of view : theXter? 



(1) That sex is predetermined in the ovum and ^ in e ation 

 spermatozoon. 



(2) That sex is determined at fertilization. 



(3) That sex is regulated subsequently to fertiliza- 

 tion ; that is to say, sex-differentiation occurs 

 during embryonic life. 



(1) With regard to the hypothesis that sex is pre- Predetermi- 

 determined in the ovum and spermatozoon, it is obvious 



1 In the sense just indicated it would be more correct to term the 

 oondition * Structural Hermaphroditism', since in some worms and other 

 invertebrates there may even be self-fertilization — a condition which 

 should be known as • Structural and Functional Hermaphroditism \ 



