MECHANICS OF THE MASCULINE AND FEMININE 137 



frog's claspers, the stag's antlers, and so on, are familiarly and 

 obviously so useful. Besides there are fundamental differences 

 in inner physiology. The human male consumes more oxygen 

 than the female per minute, since he has more red corpuscles in 

 his blood. In some caterpillars the blood is yellow in the males 

 and green in the females. W. I. Thomas has devoted an essay 

 of some fifty pages to a review of the organic differences between 

 man and woman. The ordinary criteria, employed every day by 

 the man in the street to distinguish man from woman may be 

 arranged as follows: 



Man Woman 



Hair on face Hairless face 



Skin coarse and lean Skin fine and plump 



Muscles powerful Relatively weak 



Bones heavy Bones light 



Aggressive — bass voice Reserved — treble voice 



The Role of the Ovaries 



While the primary sex characters, as such, are present and dis- 

 tinguishable from birth, quite the opposite holds for the secondary 

 sex traits. During childhood they are in abeyance or at least 

 pretty sharply suppressed. Girls and boys who are permitted 

 to dress alike, to play the same games and among whom no 

 consciousness of sex is encouraged are often difficult to tell apart. 

 The boys will be boys, and most of the girls tom-boys. 



With puberty comes a marked change of attitude toward the 

 other sex. Puberty is the time of ripening of the specific germ 

 cells. It is then the ovaries begin to secrete ova ripe for fertili- 

 zation, and the testes begin to secrete sperm ready to fertilize, 

 Before this can happen an event announced in the female by the 

 onset of menstruation, two conditions must be fulfilled in the 

 endocrine history of the individual. There must be a certain 

 atrophy and retrogression of the thymus gland, and there must 

 likewise be a similar atrophy and retirement of the pineal gland. 

 Both of these involutions of the glands of childhood must occur 

 before the normal hypertrophy and development of the sex glands 

 and their secretions can start. Besides, there must be a mini- 

 mum activity of the thyroid, adrenal and pituitary glands. 

 Without them, below a certain minimum, the reproductive organs 



V 



