COURTSHIP AND SEX 227 



sex-characters. Now, to those who are Weismannists by 

 conviction, and yet have a suspicion that there must be 

 something in Lamarckism after all, we wish to suggest for 

 critical consideration the hypothesis that this unusual 

 abundance of hormones (of the nature 'of which very little 

 is known) may exert an influence on the germ-cells in the 

 gonads and stimulate in them the determinants corre- 

 sponding to the secondary sex-characters which are being 

 especially stimulated in the parental body in question. 



E. Sex-Characters in Individual Development. — We can 



imagine that what takes place in ontogeny is somewhat as 

 follows. The fertilised egg-cell, in a way inconceivable to 

 us, is the vehicle of the determinants (or factors, or initiatives, 

 or potentialities !) of all the characters proper to the species. 

 It also contains the possibility of giving rise to the characters 

 peculiar to either sex, whether of the essential sex organs, 

 or of the subsidiary sex organs, or of distant parts of the body. 

 It is probable that whatever determines whether the fertilised 

 egg is to develop into a sperm-producer or an egg-producer 

 at the same time determines that it shall develop the masculine 

 or the feminine set of characters. The cause which deter- 

 mines that the fertilised ovum is going to develop into a 

 peacock with testes, also determines that it is going to 

 develop into a peacock with enormous and decorative tail- 

 coverts. 



We may compare the determinants of sex-characters to 

 seeds which will not germinate except in particular kinds of 

 soil. The determination of sex settles the question of 

 (protoplasmic) soil. If the fertilised egg is going to develop 

 into a male all the '* masculine seeds " will germinate ; if 

 the fertilised egg is going to develop into a female all the 

 " feminine seeds " will germinate. If the sex is imperfectly 

 differentiated, as in casual hermaphrodites, then some 

 features oi both sets — masculine and feminine — may find 

 expression. 



Darwin noted that female birds {e.g. poultry, pheasants, 

 ducks) may put on masculine plumage and some other 



