Neural Integration 175 



flex. "If," says Sherrington, "while stimulation of the skin 

 of the shoulder is evoking the scratch-reflex, the skin of 

 the hind foot of the same side is stimulated, the scratching 

 may be arrested." 13 



Then the author proceeds to show, by description and 

 diagrams, how the two excitations here involved, one from 

 the skin of the side of the body, the other from the hind 

 foot of the same side, have the "same final common path" 

 to the muscles of the hip and leg, which, however, they "use 

 to different effect"; that is, the one to excite, the other to 

 inhibit, contraction of the muscles concerned. 



At once there arises the important question: What is the 

 meaning of such antagonisms, such seeming want of har- 

 mony, as this? How deep-seated is the competition thus 

 shown? Does it amount to an "ultimate truth" in the na- 

 ture of the organism, thereby furnishing an argument in 

 favor of the "struggle of the parts" as an explanation of 

 the organism? Or is it possible that the antagonism is 

 secondary to the wider needs and activities of the organism 

 as a whole? 



A partial answer to this inquiry is found in the character 

 of the stimuli operative in the two opposing fields. "Stimu- 

 lation of the skin of the hind foot by any of the various 

 stimuli that have the character of threatening the part with 

 damage causes the leg to be flexed, drawing the foot up 

 by steady maintained contraction of the flexors of the ankle, 

 knee and hip." 14 



In other connections Sherrington dwells on the peculiari- 

 ties of effect and importance from the standpoint of adap- 

 tation, of stimuli of this class, as for example pricking, 

 strong squeezing, injurious heat, and so on. 



From the descriptions we notice that the actions of the 

 hind leg involved in the scratching-reflex are considerably 

 different from those involved in withdrawing the hind foot 

 from stimuli of harmful portent. But since the same mus- 



