SEX BIOLOGY AND SEX PSYCHOLOGY 145 



tion is immediately followed by a second act in 

 which the normal position is reversed.^ It would 

 appear in such cases that the similarity of male and 

 female internal secretion is so great that quite slight 

 changes in nervous or metabolic activity can cause 

 the nervous centres for the opposite sex's mode of 

 behaviour to become activated. 



In human beings we are confronted with various 

 grades of sexual organization and behaviour besides 

 the typically feminine and the typically masculine. 

 In the first place it is matter of common knowledge 

 that many women, who so far as their physical re- 

 productive capacity goes are perfectly normal, show 

 various mental traits which are more characteristic 

 of men, and vice versa. What is more, the ''mas- 

 culinoid" woman (to use the current jargon) tends 

 physically also to be less feminine, to have the fem- 

 inine secondary sexual characteristics . in stature, 

 form of skeleton, distribution of fat, breasts, etc. — 

 less strongly developed than normal, while the 

 "feminoid'' man shows the reverse tendency.^^ 



In trying to analyse these facts further, we are 

 brought up against new depths of complication. It 

 is becoming ever clearer that the gonads do not op- 

 erate as independent organs, but in conjunction with 

 the whole of the rest of the endocrine system — 

 thyroid, pituitary, adrenal, and the rest. In the first 

 place, it seems to be established that the reproduc- 



8 See Selous, '02; Huxley, 14. 

 10 See Blair Bell, '16. 



