50 BIOLOGICAL SOCIETY OF WASHINGTON. 



while the male is merely accessory, and need have no impor- 

 tance apart from the reproductive function. Such restriction 

 actually exists in a great many of the lower organisms and in 

 some that are quite highly organized, while throughout the in- 

 vertebrate world the physical superiority of the female is the 

 rule and that of the male is almost unknown. Female super- 

 iority is also the rule and male superiority the exception among 

 all vertebrates except birds and mammals, and sometimes 

 occurs even in these. Normal or legitimate development 

 would make it universal. But in most birds and mammals, 

 the opposite state of things exists, viz., male superiority, and 

 we are so much more familiar with these two highest types of 

 life that the impression is almost universal that the male sex is 

 in some way the primary and dominant one. I shall not waste 

 your time in attempting to refute this popular impression. 

 Those who defend it simply display their lack of acquaintance 

 with the lower forms of life. My own attention was drawn to 

 the subject by certain remarkable phenomena presented by 

 plants, but a study of the very early stages of animal life is 

 sufficient, with the least reflection, to set the whole question 

 at rest.* 



The problem is, therefore, to account for this apparentlv 

 abrupt reversal of the normal process of development as it 

 went on prior to the advent of birds and mammals. What 

 was the extraneous and illegitimate agency which began to 

 operate early in the development of avian and mammalian 

 life ? The one term which most nearly expresses it is sexual 

 selection, proposed by Darwin. In my opinion the discovery of 

 the principle of sexual selection has equal if not higher rank 



'* For a fuller, though popular, treatment of this subject, see the Forum 

 for November, 18S8, Vol. VI, p. 266.. 



