DETERMINATION OF SEX 479 



C. Experimental. Some generalisations as to the sex of the 

 offspring have been based on experiment. Thus, in one of 

 the best-known experiments, made by Prof. Emil Yung on 

 tadpoles, it was found that the percentage of females could 

 be raised from a normal of about 57 to 78, 81, and even 92, 

 according as the brood was fed with beef, fish, or flesh of 

 frogs. 



Physiological Yiew of the Problem. — As we have already 

 seen, it seems necessary to assume that the germ-cells Uberated 

 from a male or a female organism have a complete equipment 

 of hereditary qualities^a complete potential equipment for 

 both sexes. An ovum without the aid of a spermatozoon may 

 give rise to a male animal, as in the case of drone-bees. A non- 

 nucleated fragment of ovum may be fertilised by a spermatozoon 

 and develop into a perfect young organism. There is nothing 

 peculiarly female in the e^^, there is nothing peculiarly male in 

 the spermatozoon, though the contrast between the two kinds 

 of cells, considered as cells, does express in all typical cases 

 the fundamental antithesis between femaleness and maleness. 

 But the idea of feminine characters having their basis in the 

 ovum and of masculine characters having their basis in the 

 spermatozoon, is, of course, quite absurd. Every gamete has a 

 complete bisexual equipment. Many of the lower animals, e.g. 

 earthworm, leech, and snail, are hermaphrodite. A partheno- 

 genetic ovum may give rise to males or females. 



It may be said that in all ordinary cases the ovum 

 and the spermatozoon are equally the vehicle of all the 

 characteristics of either sex, and, a fortiori, that the fertihsed 

 ovum has always inherent in it the potentiality of both sexes. 

 Eventually the cells derived from it by continuous cell-division 

 will give rise, some to male, some to female offspring, or in many 

 cases (in lower animals) to hermaphrodite offspring. 



It is strange that even expert writers, who should have known 

 better, have persisted in speaking of the ovum as a female gamete 



