130 



K. S. LASHLEY AND S. I. FKANZ 



brace the entire frontal pole and the areas I, k, a, ai, and a part 

 of the anterior portions of q and d (fig. 15) including most of 

 the area described by Dollken but not extending so far over 

 the parietal surface as his figures indicate. 



In the operative experiments this entire motor area was fre- 

 quently destroyed completely without serious interference with 

 the animal's ability to form kinesthetic-motor habits. 



After purely cortical destruction we have never found any 

 motor disturbance which has persisted for as much as eighteen 

 hours after the operation; in particular there is no indication of 

 localized disturbances in the front or hind limbs resulting from 



FIG. 16. THE DISTRIBUTION OF THE STIMULABLE AREAS IN THE BRAIN OF 



THE RAT 



the destruction of corresponding regions of the stimulable area. 

 In those cases where motor disturbances were observed there 

 appears to have been always a very extensive injury to the cor- 

 pus striatum. (The material is being reexamined with reference 

 to this point.) It seems clear, then, that the loss of the habits 

 was not due directly to motor paralysis. 



In experiments 27, 30, 32, and 33 there was destruction of the 

 frontal pole including at most only the stimulable area for the 

 head and neck and, with this, complete loss of the habit. So 

 it seems almost certain that in these cases the loss of the habit 

 was due to the interruption of some other cortical reflex path- 

 ways than those included in the excitable area. The effects of 



