104 K. S. L ASHLEY AND S. I. FRANZ 



for the first five trials was: to plane, 721 seconds; to door, 35 

 seconds. The average time per trial for the last five trials was: 

 to plane, 5.4 seconds; to door, 2.4 seconds. 



Retention was tested first four days after the operation. The 

 animal was still stuporous and on this, and the following day 

 made no attempt to get upon the food box. On the seventh 

 day after the operation he ran actively back and forth from the 

 door to the back of the food box and tripped the plane twice 

 by climbing up over it from the door. On the following day 

 he was stuporous but on the ninth day he solved the problem 

 five times quite rapidly. Thereafter he became progressively 

 worse and died on the fourteenth day after the operation. 



The average time per trial for the first five trials of the re- 

 tention tests was: to plane, 179 seconds; to door, 26 seconds. 

 This is less than one fourth of the time required for the first 

 five trials of training and indicates some degree of retention 

 although no specific habits of reaction to the plane which had 

 been noted before the operation were observed to persist. 



Lesion (plate III, fig. 26). Right hemisphere. There is a 

 transverse lesion extending diagonally forward and downward 

 from just above the hippocampus through the lateral ventricle 

 to the base of the olfactory bulb. The corpus striatum is cut in 

 two transversely. The entire frontal pole is probably non- 

 functional. 



Left hemisphere. The lesion is very similar in form to that 

 on the right but penetrates less deeply toward the mesial sur- 

 face and probably leaves the mesial cortex functional. 



After extensive destruction of the antero-lateral regions of both 

 hemispheres this animal gave no indication of the retention of 

 specific habits of reaction to the plane. However, even though he 

 was stuporous for much of the time, he required only one fourth as 

 much time for the retention tests as for corresponding tests in ini- 

 tial learning. 



