120 K. S. LASHLEY AND S. I. FRANZ 



Right hemisphere: Destruction of the entire corpus callosum 

 including the knee and all cortical tissue above it and above the 

 hippocampus. A transverse lesion extends laterad from the 

 anterior end of the lateral ventricle along the forceps of the 

 corpus callosum, through the external capsule to the cortex and 

 ventrad to the cerebral peduncle. The fornix is severed with a 

 slight injury to the adjacent thalamus. The lateral ventricle is 

 much enlarged but the corpus striatum is seemingly intact. 



Left hemisphere. The corpus callosum is destroyed as on the 

 right with absorption of all cortical tissue above its level. There 

 is a diagonal lesion from the anterior horn of the lateral ventricle 

 to the base of the olfactory lobe, probably involving all the 

 cortex laterad to it. Fornix destroyed and lateral ventricle 

 enlarged until it occupies half of the horizontal area of the lobe. 

 Corpus striatum and thalamus nearly completely destroyed. 



The animal shows destruction of the antero-dorsal half of the 

 cerebrum without marked loss in ability to form simple habits. 



Experiment 37. A transverse opening, 11 by 6 mm. was 

 made in the calvarium of a large male, 200 days old, just back 

 of the frontal-parietal suture and through it a transverse frontal 

 and longitudinal temporal incisions were made through the 

 cortex, followed by great hemorrhage. Killed 30 days after 

 operation. 



The animal recovered quickly, moving about and reacting to 

 other animals within four days after the operation. He was fed 

 by hand for the first four days, then learned to find food for 

 himself but would not eat with the experimenter near. An 

 abscess developed on his neck (infection of the cerebral glands) 

 but cleared up in 20 days. He showed fewer effects of the opera- 

 tion than any other rat in this group, being the only one which 

 showed any responses to other animals. This did not extend 

 to normal sexual reactions. 



Training in the simple maze was begun twelve days after the 

 operation. At this time the animal showed no motor distur- 

 bance and was normal in his reactions to the experimenter. He 

 was first trained to go to the right in the maze and required 

 fifty trials for learning. He was then required to go to the left 



