SEXUAL SELECTION. 253 



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 

 tlie 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, puts in 

 italics the conclusion that " the greatest number of 

 abnormalities in each subject is 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 

 frequency of deficiency in females before described." Prof. 

 Macalister likewise remarksf that variations in the muscles 

 "are probably more common in males than females." 

 Certain muscles which are not normally present in man- 

 kind 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 unknow sex. It should not, however, be over- 

 looked that women would more frequently endeavor to con- 

 ceal a deformity of this kind than men. Again, Dr. L. 

 Meyer asserts that the ears of man are more variable in 

 form than those of a woman. Lastly, the temperature is 

 more variable in man than in woman, n 



The cause of the greater general variability in the male 

 sex than in the female is unknown, except in so far as sec- 

 ondary sexual characters are extraordinarily variable and 

 are usually confined to the males; and, as 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 independently of selection the 

 two sexes, from differing constitutionally, tend to vary in 



* " Proceedings Royal Soc," vol. xvi; July, 1868. pp. 519, 534. 



I- " Proc. Royal Irish Academy," vol. x, 1868, p. 123. 



X " Massachusetts Medical Soc," vol. ii, No. 3, 1868, p. 9. 



" Archiv fiir Path. Anat. und Phys.," 1871, p. 488. 



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

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

 Jan. 1, 1874, p. 97 



