INTRODUCTION 35 



explained by sexual selection, but in origin and continued 

 development are outcrops of a male as opposed to a female 

 constitution." The male element of reproduction, the sper- 

 matozoon, is an extremely minute, microscopic particle, 

 shaped like a tadpole, and moving with great activity in a 

 liquid medium by means of the lashings of its tail ; the egg 

 is a large mass of living substance or plasm charged with 

 nutriment, thousands or millions of times as large as the 

 spermatozoon, and showing no movement at all except slight 

 internal contractions and slow changes. Geddes and Thomson 

 regard the male animal as, so to speak, made up of sperma- 

 tozoa. They consider every cell in the body of the male as 

 partaking of the active, spendthrift character of the sperma- 

 tozoon, while the female tissues and the female animal as a 

 whole are, like the egg, inert, receptive, vegetative. 



It is obvious enough that none of these suggestions are of 

 any assistance in explaining the details of the unisexual 

 peculiarities ; they do not explain why the male constitution 

 of the stag is exhibited in the antlers on its head, in the 

 peacock in the feathers of its tail. With regard to size, the 

 authors admit that the superiority of the males in many 

 mammals and birds is an objection to their theory. They hold 

 that the apparent exceptions are the natural result of the 

 increased stress of external activity which is thrown upon 

 the shoulders of the males when their mates are incapaci- 

 tated by incubation or pregnancy, and they point to the 

 strengthening influence of the combats between males, and 

 to the large supplies of nourishment which the females give 

 up to their offspring. 



Eimer also states, as one of the general principles of the 

 origin of variations, that where new characters appear, the 

 males, and especially the vigorous old males, acquire them 

 first ; that the females, on the contrary, remain always at a 

 more juvenile, lower stage, and that the males transmit these 



