CUAP. VIII. Sexual Selection. ' 223 



animals, the females alone are fixed, and the males of these must 

 be the seekers. But it is difficult to understand why the males of 

 Bpeoies, 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 casesj in order 

 that the males should seek efficiently, it would be necessary that 

 they should be endowed with strong passions ; and the acquire- 

 ment of such passions would naturally follow from the more 

 eager leaving a larger number of offspring than the less eager. 



The 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 characters 

 would be much aided, if the males were more hable to vary than 

 the females — as I concluded they were — after a long . study of 

 domesticated animals. Von Nathusius, who has had very wide 

 experience, is strongly of the same opinion."^ Good evidence also 

 in fevour of this conclusion can be produced by a comparison 

 of the two sexes in mankind. During the Novara Expedition ^' 

 a vast number of measurements was made of various parts, of the 

 body in different races, and the men were found in almost every 

 case to present a greater range of variation than the women ; but I 

 shall have to recTir to this subject in a future chapter. Mr. J. 

 Wood,^^ who has carefully attended to the variation of the muscles 

 in man, puts in italics the conclusion that " the greatest number of 

 '' abnormalities in each subject i? found in the males." He had 

 previously remarked that "altogether in 102 subjects, the varieties 

 " of redundancy were found to be half as many again as in 

 " females, contrasting widely with the greater frequeocy oi 

 " deficiency in females before described." Professor Macalister 

 likewise remarks ''^ that variations in the muscles " are probably 

 " more common in males than females." Certain muscles which 

 are not normally present in mankind are also more frequently 

 developed in the male than in the female sex, although exceptions 

 to this rule are said to occur. Dr. Burt Wilder ^^ has tabulated 

 the cases of 152 individuals with supernumerary digits, of which 

 86 were males, and 39, or less than half, females, the remaining 

 27 being of uuKuown sex. It should not, however, be overlooked 



^^ ' Vortrage iiber Viehzncht,' my ' Variation of Animals ami 



1 872, p. 63. Plants under Domestication,' vol, ii. 



2^ ' Reise der Novara : Anthro- 1868, p. 75. 



pilog. Thoil,' 1887, s. 216-269. " 'Proceedings Royal Soc' vol. 



'Ilie results were calculated by Dr. xvi. July 1868, pp. 519 and 524. 



Weisbacii from measurements made ''^ 'Proc. Koyal Irisli Academy,' 



by Drs. K. Scherzer and Schwarz. vol. i. 1868, p. 123. 



On the gi-eater variability of tlie ^* 'Massachusetts Medical Soc' 



males d' domesticated animsls. «e« vol. ii. Nd. 3, 1"6S, p. 9. 



