46 BRAINS OF RATS AND MEN 



paths. In the human medulla oblongata each of these 

 various sorts of sensory fibers enters its own local 

 specific primary sensory center (tactile, gustatory, 

 etc.), and the analysis of sensibility made by the 

 peripheral sense organs is preserved in the primary 

 centers. The final integration of these diverse sensory 

 modalities is made in higher correlation centers. This 

 increase in structural complexity of the brain permits 

 much more diversified responses to external stimula- 

 tion than are possible in a tadpole, and the switch- 

 board apparatus of the higher correlation centers is 

 correspondingly enlarged. 



Recurring to our analogy of a house with many 

 doors, the medulla oblongata of larval Amblystoma 

 may be compared with a building containing a large 

 central hall, admittance to which may be gained from 

 the outside through many doors; and leading out 

 from the main hall is a smaller number of short, wide 

 corridors some of which lead directly to exits, others 

 to a common living-room in another part of the 

 dwelling. The mammalian medulla oblongata, how- 

 ever, is more like a large apartment building com- 

 posed of many suites, each with its separate entrance 

 and exit, but the inner rooms of all having free com- 

 munication from suite to suite and also with a series 

 of large common living-rooms. Here the individual 

 suites would correspond with the separate reflex 

 circuits and the common living-rooms to the higher 

 correlation centers. 



