INTEGRATION OF MOVEMENTS IN LEARNING IN THE RAT 379 



of the act leads to the establishment of a habit. The successful 

 act in the first instance appears soon, and in the second, later, 

 after successive efforts, with the production of numerous move- 

 ments. When habit formation occurs in the first way, the reflex 

 arcs, or the permeability of the synapses is already established; 

 when occurring in the second way, these paths must be devel- 

 oped from the beginning of learning, or with the appearance of 

 the successful movements. The supposition that in the last 

 way learning is established through the performance of "random 

 movements" is a logical position to assume, for sensory excitations 

 are diffuse, until one excitation produces " successful" move- 

 ments. Moreover, when habit is established in the first way, 

 through the grouping of instinctive responses, nothing radically 

 new is acquired; but in the second way, an actual modification in 

 the nervous system is supposed to occur. There appears to 

 be no experimental evidence for such a distinction in the estab- 

 lishment of habits. 



In most of these theories, something more definite is supposed 

 to occur in the organism than is stated when " pleasure-pain" 

 alone fixates the successful movement, namely, a supposed, real 

 modification within the central nervous system. When pleasure 

 now accompanies sensory excitations with the performance of 

 the successful act, instead of its increasing in general, the bodily 

 tone of the animal, and fixating a movement, it helps to establish 

 definite paths in the nervous system for this movement. When 

 the " pleasure-pain" concept is omitted, repetition of the suc- 

 cessful movement supposedly accomplished something more 

 definite. Although in both instances much is gained by an 

 increase *n definiteness of the results supposedly accomplished, 

 it is at tunes difficult to say whether the sensory excitations or the 

 responses themselves produce on the organism the effect said to 

 take place In all probability when it is sa : d that " pleasure" 

 is a factor of some consequence, sensory excitations have much to 

 do with the establishment of definite paths or neural arcs in the 

 nervous system, for " pleasure" is supposed to accompany exci- 

 tations in the senses. When mechanical repetition of the suc- 

 cessful act is said to increase the permeability of the synapses or 



