RETENTION OF HABITS BY THE RAT 



13 



seventh trial. He oriented in the starting 'compartment. The records 

 of learning and retention follow. 



Experiment 11. F3cf. Sixty-nine days old. Learning was com- 

 pleted in 60 trials with ten trials per day. Training was continued for 

 200 trials. 



The anterior third of .the cortex was destroyed. Little hemorrhage. 

 Retention was tested twenty-two hours after the operation. On the 

 first trial the rat turned into the cul de sac and ran half way to the end, 

 then turned back and went directly to the food. He made no other 

 error in the fifteen trials of the test, and followed the most direct route 

 to the food. His records for learning and retention follow. 



Experiment 12. G4cf. Seventy-three days old. Learning was 

 completed in 16 trials with 2 trials per day. Training was continued 

 for 200 trials. 



Frontal lobes were removed by a transverse incision in the region 

 of the fronto-parietal suture. Retention was tested twenty hours 

 after the operation. The animal was very weak and spastic. He 

 reacted promptly to the maze, however, orienting in the starting com- 

 partment and never hesitating at the turn in the maze. He had some 

 little difficulty in finding the food, pushing under instead of above the 

 edge of the dish. After 10 trials he began to show evidence of fatigue so 

 the remaining trials for retention were postponed for two days when he 

 had regained almost normal strength. The records of learning and re- 

 tention follow. 



