PRIMARY CHARACTERISTICS 9 



view that in the female the ova in the right ovary produce Dimorphism 

 one sex and those in the left ovary the opposite. This oi 

 wild assumption, however, is directly controverted by the 

 simple facts that in birds, and to a great extent in the 

 mammalian Orniihorhynchus as I have myself found, 

 the right ovary atrophies and the left alone remains 

 functional, and that women and animals from whom 

 one ovary has been removed have subsequently borne 

 offspring of both sexes. An extensive investigation 

 recently completed has shown that either ovary, as 

 judged by the presence of corpora lutea, may furnish 

 ova that develop into male and female offspring 1 . 



It has been suggested by Bateson 2 and others that Mendeiian 



3& . . J . laws m rela- 



pnmary sex-determination in the gametes is purely tion to sex- 

 hereditary and conforms with Mendeiian laws. Even if ti Q^ rn 

 this were so in actual fact, it would be falsified by repro- 

 ductive results ; for to obtain proof of this contention 

 in regard to mammals it would be necessary to ensure 

 the fertilization of every ovum, and that is impossible. 



With regard to the proposition contained in the second BisexuaUsm 

 subdivision, Heape 3 and many other writers hold that 

 although the dominant sex may be predetermined in the 

 gamete, yet there is in each a latent anlage of the opposite 

 sex which may become active and predominant before 

 fertilization under certain conditions of nutrition, 

 parental vigour and general environment. 



Arising from this view, which I believe is correct, so 

 far as it goes in the life-history of the individual, there 

 have been a number of interesting studies concerning 

 the ratio of the sexes, both in man and animals, under 

 different conditions. From a statistical point of view the Effect of en- 

 results are not satisfactory. On the one hand, it has been and nutrition. 

 stated 4 that in the aristocracy presumably well-fed 



1 Murray, J. G., Butt. Johns Hopk. Hosp., 1918, vol. xxix, p. 

 275. 



2 Bateson, W., Report to Evolution Committee of Roy. Soc., rep. i, 

 1902, Lond. 



3 Heape, W., Proc. Camb. Phil. Soc., 1907, vol. xiv, p. 121. 



4 Punnett, R. C., Proc. Camb. Phil. Soc., 1904, vol. xii, p. 262. 



