Phenomenon of Sex 



of the male or the female sex. A vast amount 

 of ingenuity has been expended by zoologists in 

 the attempt to ascertain what it is that deter- 

 mines sex. Many theories have been advanced, 

 but no one of them has obtained anything like 

 general acceptance, because its opponents are 

 able to adduce facts which appear to be incom- 

 patible with it. 



It is tempting to try to interpret the pheno- 

 menon of sex on the assumption that the female- 

 producing biological molecule or unit is an 

 isomeride of the male-producing cell. Certain 

 facts, however, seem to negative the idea, as, for 

 example, the occasional appearance in an indi- 

 vidual of one sex of characteristics of the other 

 sex. 



Possibly the attempts to explain the pheno- 

 mena of sex-production on a Mendelian basis 

 may prove to be more successful. It seems not 

 impossible that each fertilised egg contains 

 material which is capable of developing into 

 male generative organs and material which is 

 capable of developing into female generative 

 organs, but that only one kind of material, that 

 which dominates, succeeds in developing. The 

 number of what are known as " X-elements " 

 that happen to be present in the fertilised egg 

 appear to decide which kind of material is to be 

 dominant. 



But the problem of the determination of sex, 

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