CHAPTER VII 

 THE GERM CELLS OF HERMAPHRODITIC ANIMALS 



MANY of the most interesting biological problems 

 are those connected with the phenomenon of sex. 

 The term "sex" is applied to the soma or body of an 

 organism ; it indicates the presence of certain mor- 

 phological and physiological characteristics, which 

 may be separated into primary and secondary sexual 

 characters. The primary sexual characters are those 

 immediately connected with the reproductive organs ; 

 the secondary sexual characters, such as the beard of 

 man, the brilliant feathers and beautiful songs of 

 many male birds, and the antlers of the moose, repre- 

 sent differences between male and female individuals 

 not directly concerned with the production of germ 

 cells. It is customary to speak of male germ cells 

 and female germ cells ; this is not strictly proper, 

 since in only a few special cases can we predict the 

 sex of the individual which will develop from an egg. 

 Moreover, every germ cell must contain the poten- 

 tiality of both sexes since sooner or later its descend- 

 ants will give rise, some to male, some to female or 

 perhaps to hermaphroditic offspring. Thus the egg 

 is an initial hermaphrodite; it may or may not be- 

 come an eventual hermaphrodite according to the sex- 

 ual condition of the individual to which it gives rise. 



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