162 REFLEX ACTJON AND 



it now that the foot was removed. After some moments 

 of agitation, as if the brainless creature were seeking a new 

 means of accomplishing its end, the motor stimulus flowed 

 out in a different direction, causing the animal to bend 

 the limb of the other side till with its foot it succeeded 

 in rubbing the irritated region. 



Thus, as Vulpian says, " Each spot irritated acts as a 

 kind of spring for calling into play a mechanism which 

 varies according to the point excited, and according to the 

 intensity of the excitation. But each mechanism that is 

 called into play always determines a tendency to remove 

 the region irritated from the irritating cause. The efforts 

 differ, the mechanism differs also, but both are always 

 appropriate, and, as it were, chosen." 



Multitudes of reflex acts having the same general 

 characteristics are quite familiar to us from their occur- 

 rence in the higher animals and in man. Of these it 

 may suffice to mention the closure of the eyelid before an 

 approaching body, the rapid drawing away of the paw or 

 hand from injury, the throwing out of the arms in the act 

 of falling, the movements of suction and deglutition 

 following impressions on mouth and throat, together with 

 the acts of vomiting, coughing, and sneezing. 



It will have been seen that there are two distinct 

 sides to the process which we have hitherto been consider- 

 ing. We have to take into account what occurs on the 

 side of ' ingoing currents,' in the nervous centre; and 

 also what occurs on the side of ' outgoing currents.' The 

 latter processes are the distinct sequences of the former ; 

 and if we have inverted the proper order of description, 

 and have referred more especially, in the first place, to 

 the gradual growth of the power of performing adaptive 

 movements, it is only because such an inversion of the 



