SEXUAL SELECTION. 219 



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

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

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

 in man, puis in italics the conclusion that "the greatest number 

 "of abnormaiities in each subject is found in the males." He 

 had previouslj 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 frequency of 

 "deficiency in females before described." Professor Macalister 

 likewise remarks^ that variationis in the muscles "are probably 

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

 are not normally present in mankind are also more freauently 

 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 unknown sex. It should not, however, be overlooked 

 that women would more frequently endeavor to conceal a de- 

 formity of this kind than men. Again, Dr. L. Meyer asserts that 

 the ears of man are more variable in form than those of woman.^ 

 Lastly the temperature is more variable in man than In woman.^ 

 The cause of the greater general variability in the male sex, 

 than in the female is unknown, except in so far as secondary 

 sexual characters are extraordinarily variable, and are usually 

 confined to the males; and, a,s we shall presently see, this fact is, 

 to a certain extent, intelligible. Through the action of sexual 

 and natural selection male animals have been rendered in very 

 many instances widely different from their females; but in- 

 dependently of selection the two sexes, from differing constitu- 

 tionally, tend to vary in a somewhat different manner. The fe- 

 male has to expend much organic matter in the formation of her 

 ova, whereas the male expends much force in fierce contests with 

 his rivals, in wandering about in search of the female, in exert- 

 ing his voice, pouring out odoriferous secretions, &c.: and this 

 expenditure is generally concentrated within a short period. The 

 great vigor of the male during the season of love seems often to 

 intensify his colors, independently of any marked difference 

 from the female.'^ In mankind, and even as low down in the 



2* 'Proceedings Royal Soc' vol. xvi. July 1868, pp. 519 and 524. 



^ 'Proc. Royal Irish Academy,' vol. x. 1868, p. 123. 



=« 'Massachusetts Medical Soc." vol. ii. No. 3, 1868, p. 9. 



^ 'Archiv fur Path. Anat. und Phys.' 1871, p. 488. 



28 The conclusions recently arrived at by Dr. J. Stockton Hough, 

 on the temperature of man, are given in the 'Pop. Science Review,' 

 Jan. 1st, 1874 p. 97. 



=» Prof. Mantegazza is inclined to believe ('Lettera a Carlo Darwin,' 

 'Archivio per I'Anthro-pologia,' 1871, p. 306) that the bright colors, 



