194 BRAINS OF RATS AND MEN 



In the first report of this series of researches Lash- 

 ley and Franz (1917, p. 133) wrote: 



The ability of the animals to form habits after the loss of 

 those parts of the brain which are normally used in learning, the 

 reestablishment of motor control after the loss of the stimulable 

 area of the cortex and of the corpus striatum, and the seeming 

 equipotentiality of the different parts of the frontal pole in the 

 functioning of complex habits go far toward establishing the 

 complete functional interchangeability of all parts of the cerebral 

 cortex. 



This motif reappears in all of the subsequent re- 

 ports, but to me it seems that this work in its entirety 

 by no means points in that direction, even in the case 

 of so simple a brain as that of the rat. The experi- 

 ments do show less sharply defined mosaic localiza- 

 tion of function than has often hitherto been sup- 

 posed. But this is very far from "complete functional 

 interchangeability of all parts," which is a priori im- 

 probable and is distinctly negatived by the experi- 

 ments reported. That there is a functional specifici- 

 ty of some sort corresponding to the known anatomi- 

 cal specificity of the cortex of the rat there can be no 

 reasonable doubt. The problem is to devise experi- 

 ments which are adequate to bring this specificity to 

 light and reveal its character. The experiments al- 

 ready reported have gone a long way in that direc- 

 tion, especially in excluding certain types of mosaic 

 localization formerly widely accepted. 



In discussing the double-platform box habit, Lash- 

 ley (1920, p. loi) concludes, **No single part of the 



