CEREBRAL FUNCTION IN LEARNING 95 



Operated animals. Four animals were trained after destruc- 

 tion of the frontal pole of the cerebrum. Three of them finished 

 training and only limitation of time prevented the fourth from 

 learning the problem. Their individual records are given below. 



Number 1. Small female, 94 days old. The frontal pole of the 

 cerebrum was injured by a transverse incision carried diagonally forward 

 from the fronto-parietal suture. Training was begun 72 days after 

 operation. She became ill during the latter part of training and had 

 to be given a week's rest with full allowance of food. 



Trials required for learning 100 



Lesion: Plate III, figure 1. The frontal poles of both hemispheres, 

 between and in front of the forceps of the callosum were completely 

 destroyed. 



Number 2. Small female, 94 days old. The frontal pole of the 

 cerebrum was injured as in the case of number 1. Training was begun 

 72 days after operation. 



Number of trials required for learning 70 



Lesion: Plate III, figure 2. Practically all of both hemispheres 

 in front of the vertical plane of the knee of the corpus callosum was 

 destroyed. The left olfactory tract was severed. Both corpora 

 striata were injured, that on the left most extensively. 



Number 3. Small female, 73 days old. Operation as in the case 

 of number 1. Training was begun 72 days after operation. 



Number of trials required for learning .70 



Lesion: Plate III, figures. All of the cortex lying above and 

 between the forceps of the callosum was completely destroyed. The 

 subcortical ganglia were uninjured. 



Number 4- Medium sized male, 150 days old. Both frontal lobes 

 were destroyed by transverse incisions. Recovery was very slow. 

 The animal lay for four days in coma and appeared to be stuporous 

 up to the beginning of training, 60 days after operation. During train- 

 ing he was very erratic, trying to climb out of the training box, or lying 

 quiet for long periods. After 30 trials, however, he gave certain evi- 

 dence of discrimination, turning back repeatedly before he reached 

 the end of the dark alley, when errors were made, and advancing into 



