108 K. S. LASHLEY AND S. I. FRANZ 



Experiment 30. The frontal poles of the cortex of a medium 

 sized male rat, 140 days old, were transsected with a spear- 

 pointed needle, introduced through small trephine holes in the 

 parietal bones just behind the fronto-parietal suture. The 

 animal had been trained for 25 trials on the inclined-plane box. 

 The average time per trial for the first five trials was: to plane, 

 3382 seconds; to door, 39 seconds. That for the last five trials 

 was: to plane, 43.0 seconds; to door, 10.4 seconds. During 

 training the animal developed an easily recognizable method of 

 springing the plane. He regularly placed his right fore foot on 

 the end of the plane and kept it there while he thrust his nose 

 under the plane. In this position his weight was supported 

 largely by the right fore foot and the end of the plane was pulled 

 down. 



Retention was tested first on the second day after the opera- 

 tion while the animal was still weak and stupor ous. He moved 

 about slowly, smelling in the corners of the restraining cage and 

 once crossed the top of the food box but gave no specific reaction 

 to the plane. He was tested daily for thirty minutes there- 

 after for fourteen days. For the first three days he was very 

 active and quite wild, squeaking and jumping whenever touched; 

 later he became tame but rarely moved away from the door of 

 the restraining cage. 



Lesion (plate III, fig. 30). Right hemisphere. There is a 

 lesion of the cortex above the dorsal and lateral surfaces of the 

 gyrus hippocampus with prolongation of the lateral ventricle 

 along the external capsule into the occipital lobe with probable 

 degeneration of all the fibers in this region. There is a complete 

 separation of the hippocampus from the external capsule with 

 probable degeneration of the fibers in the capsule. There is 

 a transverse lesion also extending forward along the corpus cal- 

 losum, around the knee to the floor of the lateral ventricle, and 

 laterad through the anterior end of the corpus striatum to the 

 external capsule. This lesion does not penetrate far enough to 

 injure the peduncle so that the ventro-lateral face of the frontal 

 pole is probably intact. 



Left hemisphere. There is a transverse lesion extending 



