25^ THE DESCENT OF MAN. 



reason^ for even if the ova were detached before fertiliza- 

 tion, and did not require subsequent nourishment or pro- 

 tection, there would yet be greater difficulty in transorting 

 them than the male element, because, being larger than 

 the latter, they are produced in far smaller numbers. So 

 that many of the lower animals are, in this respect, analo- 

 gous with plants.* The males of affixed and aquatic ani- 

 mals having been led to emit their fertilizing elements in 

 this way, it is natural that any of their descendants, which 

 rose in the scale and became locomotive, should retain the 

 same habit; and they would approach the female as closely 

 as possible, in order not to risk the loss of the fertilizing 

 element in a long passage of it through the water. With 

 some few of the lower animals, the females alone are fixed, 

 and the males of these must be the seekers. But it is dif- 

 ficult to understand why the males of species, of which the 

 progenitors were primordially free, should invariably have 

 acquired the habit of approaching the females, instead of 

 being approached by them. But in all cases, in order that 

 the males should seek efficiently, it would be necessary that 

 they should be endowed with strong passions; (and the 

 acquirement of such passions would naturally follow from 

 the more eager leaving a larger number of offspring than 

 the less eager. ^ 



[jlie great eagerness of the males has thus indirectly led 

 to their much more frequently developing secondary sexual 

 characters than the females. But the development of such 

 chai'acters would be much aided, if the males were more 

 liable to vary than the females as I concluded they were 

 after a long study of domesticated animals. A Von Nathu- 

 sius, who has had very wide experience, is s^'ongly of the 

 same opinion, f Good evidence also in favor of this con- 

 clusion can be produced by a comparison of the two sexes 

 in mankind. J3uring the No vara Expedition J; a vast 



*Prof. Sachs (" Lehrbuch der Botanik," 1870, s. 638), in speaking 

 of the male and female reproductive cells, remarks, ' verhalt sich 

 die eine bei der Vereinigung activ, . . . die andere erscheint bei 

 der Vereinigung passiv." 



t" Vortrage uber Viehzucht," 1872, p. 63. 



X "Reise der Novara, Anthro])olog. Theil," 1867, ss. 216-269. The 

 results were calculated by Dr. Weisbach from measurements made 

 by Drs. K. Scher/er and Schwarz. On the greater variability of the 

 males of domesticated animals, see my *' Variation of Animals and 

 Plants under Domestication," vol. ii, 1868, p. 75. 



