174 ANIMAL LIFE AND HUMAN PROGRESS 



functional activity of this inhibition is dependent upon the 

 integrity of the genital gland. Remove the ovary and the 

 inhibition no longer works. The castrated hen dresses like 

 a cock. 



What then is this inhibition ? Were it not for the 

 existence of henny cocks we might be tempted to ascribe the 

 effect to the direct action of the ovary itself. But the exist- 

 ence of these birds clearly puts such a simple explanation out 

 of court, for it is certain that they do not possess an ovary. 

 At this stage Morgan's experiments come into the story. He 

 has castrated a number of these henny cocks and has arrived 

 at the curious and paradoxical result that the removal of the 

 male genital gland leads to the assumption of the complete 

 male plumage. In the henny cock as in the hen herself the 

 activity of the inhibitor is dependent upon the integrity of 

 the genital gland. But the inhibition itself is a definite 

 thing, transmitted on Mendelian lines, and only dependent 

 upon the sexual gland in so far as it requires some secretion 

 from either ovary or testis to call it into activity. 



From experimental work of this sort the nature of secondary 

 sexual characters is assuming a new aspect. Qualities which 

 we have hitherto regarded as the perquisite of one sex may 

 nevertheless occur and be perpetuated in the other. For 

 analysis suggests that they are not merely the expression of a 

 particular form of sexual gland, but are, in many cases at 

 any rate, based upon independent hereditary factors, and 

 therefore subject to independent transmission. Whether 

 there will be any economic outcome from all this, for my own 

 part I feel little interest to inquire. After all, we are men 

 and women before we are breeders of animals and plants. 

 It is the evaluation of our own sexual properties, the deter- 

 mination of our own potentialities and limitations, that we are 

 coming to discern in the study of these secondary sexual 

 characters. They must ever remain the warp upon which is 

 woven the woof of our own social life. It is for us to try 

 so to understand our material, its peculiar weaknesses and 

 strength, that upon the warp allotted to us we may weave 

 our fabric at once both splendid and enduring. 



Vm 



