464 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 1918. 



through which the species has attained its present organization. "' 

 Darwin said that the plumage and song of the male bird were trans- 

 mitted by the selection on the part of the female of the gayest bird 

 and the best singer. Brooks goes deeper and finds the cause for 

 these secondary sexual characteristics in the power of the male cell 

 to transmit the variations. He does not deny that the female may 

 choose the best singer but affirms that the male must lead in varia- 

 tions from his very nature. 



Geddes and Thompson carry forward still further the criticism 

 of Wallace and Brooks. Wallace accounts, on the theory of 

 natural selection, for the dull colors of the female and for the more 

 brilliant colors and song of the male. Darwin on the other hand 

 rivets his attention upon the gorgeous colors, the plumes, combs 

 and wattles of the male, accounting for them by the theory of 

 sexual selection but fails to tell us why the same process does not 

 brighten up the coat of the female. The mere statement of the 

 position must make it clear that there is some deeper cause than 

 that discovered by either Daxwin or Wallace, some internal factor 

 much more powerful in its operation than any external cause. 

 Geddes and Thompson finds this in the essential difference be- 

 tween the sexes. " The females incline to passivity, the male to ac- 

 tivity." The female cochineal insect " spends much of its life like a 

 mere quiescent gall on the cactus plant. The male, on the other hand, 

 in his adult stage is agile, restless, and short lived." So with the 

 other insects and other animals. The male is more active, while the 

 female is passive. 



For completeness of argument, two other facts may here be simply men- 

 tioned: (a) At the very threshold of sex difference we find that a little active 

 cell or spore, unable to develop itself, unites in fatigue with a larger more qui- 

 escent individual. Here at the very first is the contrast between male and 

 female. ( b ) The same antithesis is seen when we contrast the actively motile, 

 minute, male element of most animals and many plants with the larger pas- 

 sively quiescent female cell or ovum. 



To the above contrast of general habits two other items may be added on 

 which accurate observation is still unfortunately very restricted. In some 

 cases the body temperature, which is an index to the pitch of life, is distinctly 

 lower in the females, and has been noted in cases so widely separate as the hu- 

 man species, insects, and plants. In many cases, furthermore, the longevity of 

 the female is much greater. Such a fact as that women pay lower insurance 

 premiums than do men, is often popularly accounted for by their greater im- 

 munity from accident, but the greater normal longevity on which the actuary 

 calculates, has, as we begin to see, a far deeper and constitutional explanation. 



The agility of males is not merely an adaptation to enable that sex to exercise 

 its functions with relation to the other, but is a natural characteristic of the 

 constitutional activity of maleness ; and the small size of many male fishes is 

 not an advantage at all, but simply again the result of the contrast between the 

 more vegetative growth of the female and the costly activity of the male. So, 

 brilliancy of color, exuberance of hair and feathers, activity of scent glands, 



