Allen, Association in the Guinea Pig. 341 



is his food — a desired thing, an end. The guinea pig is still 

 wearing out the floor of the same labyrinth. 



Were we to anticipate our later work we would suggest 

 that the significant contrasting features in the two animals are 

 their nerv^ous systems. In the one a mature nervous system is 

 accompanied by psychical maturit}- ; in the other, neural imma- 

 turity permits great psychical development. 



Part II. The Central Nervous System of the Guinea Pig. 



Introdiiction. 



The investigation of the central nervous system of the 

 guinea pig has for its purpose the description of the conditions 

 present at birth, and the changes in the medullation of fibers 

 between birth and maturity. 



When an adequate notion of the nervous system and its 

 growth changes has been obtained, it will be desirable to cor- 

 relate these facts with the physical and psychical responses de- 

 scribed in a previous part of this work. In view of the corre- 

 sponding investigation of the white rat, a comparison will be 

 made between the nervous system of the guinea pig and that of 

 the white rat. 



The progressive medullation of the central nervous system 

 has been correlated by many authors with the progressive ac- 

 quisition of function.^ Nevertheless, Watson has shown in the 

 case of the white rat ■ that both the peripheral and the central 

 nervous systems are entirely without medullated fibers at birth, 

 while man\' impulses are at that time transmitted to the central 

 system and there coordinated ; and that complex associative 

 processes are present before the medullation of those areas 

 which may mediate associations in the cortex. Furthermore, 



' A summary of the previous work on medullation will be found on pages 

 108 to III of Animal Education. The discussion of Flechsig's work is on 

 Paiges 6 and 7, and a criticism of his wholesale correlations between function and 

 medullation on pages 121-122. 



■■^ Animal Education, p. 117. 



149] 



