DARWIN, AND THE ORIGIN OF SPECIES 2OI 



and that the structure of every part of its frame must be 

 adapted to its conditions of life." 1 



In Romanes's hands, Mivart's old argument, which made Dar- 

 win more strongly convinced of the correctness of his own views 

 than before, assumes a new form ; for he attempts to show that 

 many reflex actions have been brought about by the coadaptation 

 of parts which were "severally useless," and that the degree of 

 adaptation exhibited by the resulting whole is often so slight as 

 to be incompatible with belief that the reflex response has now, 

 or ever had, " selective value." 



While he holds natural selection incompetent to account for 

 the mechanism which brings about a reflex action of this sort, he 

 believes that this mechanism may be satisfactorily explained as 

 the inherited effect of use ; for he says that the doctrine that 

 constantly associated use of the same parts for the performance 

 of the same action will progressively organize these parts into a 

 reflex mechanism, is the very essence of the theory of use-inheri- 

 tance, no matter how high a degree of coadaptation may thus 

 be reached on the one hand, or how low a degree of utilitarian 

 value on the other. 



" In our organization," he says in illustration, " there is a 

 reflex mechanism which insures the prompt withdrawal of the legs 

 from any source of irritation supplied to the feet. For instance, 

 after a man has broken his spine in such a manner as totally to 

 interrupt the functional continuity of his spinal cord and brain, 

 the reflex mechanism in question will continue to retract his 

 legs when his feet are stimulated by a touch, a burn, etc. This 

 action is clearly a responsive action, and, as the man neither feels 

 the stimulus nor the resulting movement, it is as clearly a 

 reflex action. The question now is as to its mode of origin and 

 development. 



" I ask whether we can reasonably hold that this particular 

 reflex action comparatively simple though it be has ever 

 been of selective value to the human species, or to the ancestors 

 thereof? Even in its present fully formed condition it is fairly 

 questionable whether it is of any adaptive value at all. The 

 movement performed is no doubt an adaptive movement; but 



1 "Origin," pp. 182-186. 



