202 THE FOUNDATIONS OF ZOOLOGY 



is there any occasion upon which the reflex mechanism concerned 

 therein can ever have been of adaptive usef Until a man's legs 

 have been paralyzed as to their voluntary motion, he will always 

 promptly withdraw his feet from any injurious source of irritation 

 by means of his conscious intelHgence. True, the reflex mechan- 

 ism secures an almost inappreciable saving in the time of response 

 to a stimulus as compared with the time required for response to 

 an act of will ; but the difference is so exceedingly small, that we 

 can hardly suppose the saving of it in this particular case can be 

 a matter of any adaptive — much less selective — importance. 



" Nor is it more easy to suppose that the reflex mechanism 

 has been developed by natural selection for the purpose of replac- 

 ing voluntary action when the latter has been destroyed or sus- 

 pended by grave spinal injury, paralysis, coma, or even ordinary 

 sleep. In short, even if for the sake of argument we allow it to 

 be conceivable that any human being, ape, or still more distant 

 ancestor, has ever owed its life to the possession of this mechan- 

 ism, we may still be certain that not one in a million can have 

 done so. And if this is the case with regard to the mechanism 

 as fully constructed, still more must it have been the case with 

 regard to all the previous stages of construction. For here, with- 

 out elaborating the point, it would appear that a process of con- 

 struction by survival of the fittest is incomprehensible." ^ 



As Romanes says that this is a typical illustration of the diffi- 

 culty he finds in explaining the production of reflex actions in 

 general by selection alone, it may be worth while to examine it ; 

 although the source of Romanes's difficulty is hard to discover. 



When all the complicated muscles of the foot and leg and 

 trunk are at rest, the irritation of the sole may be followed by vio- 

 lent retraction of the foot, but when they are brought into bal- 

 anced action in the complex movements of walking or running, 

 this does no more than to counterbalance and thus arrest some 

 of these movements. The importance of perfect locomotor coor- 

 dination is so clear to all that a moment's thought must show 

 that the past history of our race has furnished abundant oppor- 

 tunities for the perfection of this coordination by selection. No 

 one who reflects how often the life of a barefooted savage and 



1 " Darwin and after Darwin," II., pp. 73-77. 



