8 S. I. FRANZ AND K. S. LASHLEY 



Animals tested for retention without overtraining 



Experiment 1. G2 $ . Ninety-four days old at the beginning of 

 training. Learning was completed in 54 trials at 10 trials per day. 

 No overtraining. 



Operation through two trephine holes, followed by extensive hemor- 

 rhage. Retention was tested twenty-five hours after the operation. 

 The animal was constantly irritated by inflamation of the nasal sinuses 

 but was otherwise in good condition. Orientation in starting compart- 

 ment was normal. In every trial except the second the animal kept 

 close to the right-hand wall of the middle alley and cut close to the end 

 of the partition. On the second trial she turned into the entrance of 

 the cul de sac but did not advance more than two inches. Various 

 tests suggest that she was anosmic. A comparison of the records of 

 learning and retention follows. 



Experiment 2. Gl 9 . Ninety-four days old. Learning was com- 

 pleted in 23 trials with 2 trials per day. No overtraining. 



Operation through large transverse opening, followed by consid- 

 erable hemorrhage but with recovery of motor coordination within 

 half an hour. Retention was tested twenty-six hours after the opera- 

 tion. The rat was very weak, falling over when attempting to make 

 quick turns or to scratch the dressing on her head. She oriented in 

 the starting compartment and gave no evidence of exploratory snif- 

 fing in the maze. On the first trial she turned into the cul de sac and 

 wandered back and forth for a few seconds, then went directly to the 

 food. A second error was made on the eleventh trial. The other 

 trials were made correctly but at a rather slow rate. The rat made 

 frequent long stuporous pauses and spent a good bit of time also in 

 scratching at the dressing on her head. On the following day she was 

 given 20 trials in the maze and in every case reached the food without 

 error and in less than four seconds. The records of learning and re- 

 tention follow. 



