c hap. VII. 
THE EACES OF MAN. 
249 
s Pecial service to him. The intellectual and moral 01 
s «cial faculties must of course be excepted from this re- 
mark ; hut differences in these faculties can have had 
little or no influence on external characters, lhe vari- 
ability of all the characteristic differences between the 
races, before referred to, likewise indicates that these 
hifterenccs cannot be of much importance , for, had 
they been important, they would long ago have been 
either fixed and preserved, or eliminated. In this 
Aspect man resembles those forms, called by naturalists 
Protean or polymorphic, which have remained extiemely 
variable, owing, as it seems, to their variations being of 
a n indifferent nature, and consequently to their having 
leaped the action of natural selection. 
We have thus far been baffled in all our attempts 
account for the differences between the races of man , 
hut there remains one important agency, namely Sexual 
^election, which appears to have acted as powerfully 
°U man, as on many other animals. I do not intend 
to assert that sexual selection will account lor all the 
differences between the races. An unexplained resi- 
duum is left, about which we can in our ignorance 
only say, that as individuals are continually born with, 
f °r instance, heads a littlo rounder or narrower, and 
With noses a little longer or shorter, such slight dif- 
ferences might become fixed and uniform, if the un- 
known agencies which induced them were to act in a 
more constant manner, aided by long-continued inter- 
crossing. Such modifications come under the provi- 
sional class, alluded to iu our fourth chapter, which for 
the want of a better term have been called spontaneous 
variations. Nor do I pretend that the effects ol sexual 
selection can be indicated with scientific precision ; but 
it can be shewn that it would be an inexplicable fact if 
man had not been modified by this agency, which has 
