!6 the evolution of sex. 



It is possible that the reader may urge as a difficulty against the 

 above contrast the exceedingly familiar case of the male bees or 

 "drones." It must be frankly allowed that exceptions do indeed 

 occur, though usually in conditions which afford a key to the 

 abnormality. Thus it will be allowed that the "drones" are in a 

 peculiar position as male members of a very complex society, in 

 which what is practically a third sex is represented by the great body 



of "workers." They are no more fair 

 examples of the natural average ol 

 males than the hard-driven wives of 

 the lazy Kaffir are of the normal func- 

 tions of women. Nor is the exception 

 even here a real one, for the drone, 

 although passive as compaied with 

 the unsexed workers, is active when 

 compared with the extraordinarily 

 passive queen. 



To the above contrast of general 

 habit 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 the life, is 

 distinctly lower in the females, as has 

 been noted in cases so widely separate 

 as the human species, insects, and 

 Fig. 7.— Both sexes of a Flea— the jigger or plants. In many cases, furthermore, 



Chigoe (SarcopsylU penetrans): Ae female ^ ^ • Qf ^ females ig much 



much swollen with eggs. — r rom Leuckart. » J 



greater. Such a fact as that women 

 pay lower insurance premiums than do men is often popularly 

 accounted for by their greater immunity from accident; but the 

 greater normal longevity on which the actuary calculates, has, as we 

 begin to see, a far deeper and constitutional explanation. 



III. Size. — Among the higher animals, there are curious 

 alternations in the preponderance of one sex over another in size. 

 Thus among mammals and birds the males are in most cases the 

 larger; the same is true of lizards; but in snakes the females prepon- 

 derate. In fishes the males are on an average smaller, sometimes 

 very markedly so, even to the extent of not being half as large as their 

 mates. Below the line, among backboneless animals, there is much 

 greater constancy of predominance in favor of the females. Thus 

 among insects the more active males are generally smaller, and often 

 very markedly; of spiders the same is true, and the males being often 



