INTERNAL CAUSES OF VARIATION 195 



to which they will develop depends very much upon the sex of 

 the individual. How much allowance to make on account of sex 

 in comparing one individual with another of a different sex we 

 are in most cases unable to say, not from the impossibility of 

 knowing, but from the fact that in respect to most characters 

 the matter has not yet been worked out. It is easily possible, 

 however. 



For example, in respect to stature, men are 8 per cent taller 

 than women, so that when the heights of the latter are multi- 

 plied by i.oS 1 the two are strictly comparable, and not before. 

 When this is done the difference due to sex has been eliminated, 

 and the statures of men and women may be directly compared. 



In general, males and females exhibit the same characters, 

 but in varying degrees. For example, the woman as well as the 

 man has hair on the face, but in less amount ; the male as well 

 as the female has nipples, but they are rudimentary. Among 

 mammals and the domestic animals generally the male is heavier 

 in front, generally of a more robust build, and considerably 

 larger than the female, a distinction that by no means holds 

 in animal life generally. 



In the present state of knowledge we simply know that the 

 general appearance of the individual and its character devel- 

 opment are largely dependent upon its sex ; but to what exact 

 extent remains in most cases to be determined, and the deter- 

 mination must be made before we can compare individuals of 

 different sexes with any degree of accuracy. Without a doubt 

 distinctions in sex have been greatly overworked, the differ- 

 ences being mostly of degree rather than of kind, 2 and far less 

 consequential than has been supposed. 



Individuals deprived of their sexual organs by castration or 

 by spaying do not develop their primary sexual characters. The 

 castrated male is not a female, as is sometimes erroneously 

 believed, but a male arrested in his development ; and the spayed 

 female is an undeveloped female. As would be expected, both 



1 These data are the result of Galton's study of the stature of English people. 

 See Galton, Natural Inheritance. 



2 It is idle to attempt to prove that certain characters, aside from those of 

 reproduction, are especially identified with one sex. 



