262 THE DESCENT OF MAN 



and the^'odor) emitted by it, are likewise in some manner 

 connecteQ'. With the breeds of sheep the number of hairs 

 within a given space and the number of the execretory 

 pores are related. ^ If we may judge from the analogy of 

 our domesticated animals, many modifications of struct- 

 ure in man probably come under this principle of correlated 

 development. __ 



We have now seen that the external characteristic differ- 

 ences between the races of man cannot be accounted for in a 

 satisfactory manner by the direct action of the conditions of 

 life, nor by the effects of the continued use of parts, nor 

 through the prinjciple of correlation. We are therefore led 

 to inquire whether slight individual differences, to which 

 man is eminently liable, may not have been preserved and 

 augmented during a long series of generations through natural 

 selection. But here we are at once met by the objection that 

 beneficial variations alone can be thus preserved; and as far 

 as we are enabled to judge, although always liable to err on 

 ]this head, none of the differences between the races of man 

 .are of any direct or special service to him. The intellec- 

 tual and moral or social faculties mnst of course be excepted 

 from this remark. The great variability of all the external 

 differences between the races of man likewise indicates that 

 they cannot be of much importance ; for, if important, they 

 would long ago have been either fixed and preserved, or 

 eliminated. In this respect man resembles those forms, 

 called by naturalists protean or polymorphic, which have 

 remained extremely variable, owing, as it seems, to such 

 variations being of an indifferent nature, and to their hav- 

 ing thus escaped the action of natural selection. 



We have thus far been baffled in all our attempts to 

 account for the differences between the races of man; but 



hereditary. Now this hair is as coarse and harsh as that of a horse's mane, 

 while the hair of other colors is fine and soft. 



"' On the odor of the skin, G-odron, "Sur rsspeoe," torn. il. p. 217. On 

 the pores in the skin, Dr. Wilckens, "Die AufgabenderLandwirth. Zootechnik, " 

 1869, s. 7. 



