16 S. I. FRANZ AND K. S. LASHLEY 



the exploratory sniffing at cracks and corners which is so char- 

 acteristic of the untrained rat in the maze. All were tested im- 

 mediately after the retention tests by being placed in a strange 

 cage with food and all spent at least thirty seconds in exploring 

 the cage before pausing at the food, so that the lack of explora- 

 tory activities in the maze must be looked upon as due to re- 

 tention of the habit and not to a general sluggishness resulting 

 from the operations. The three rats which were not over- 

 trained oriented in the starting compartment and two regularly 

 followed the path marked in figure 1. The abnormality of be- 

 havior of the third (Gl 9 ) was probably due to loss of sensi- 

 tivity of the vibrissae. 



The animals which were overtrained required 87 per cent less 

 time for the first fifteen trials after operation and made 90 per 

 cent fewer errors than in their initial learning. This, in addi- 

 tion to the data on individual behavior in the maze shows that 

 there was practically no loss of the habit resulting from the de- 

 struction of the frontal lobes. 



There is an apparent difference in the amount of retention be- 

 tween animals which were over-trained and those which were 

 trained only until they had learned the problem. This differ- 

 ence is probably not so great as is indicated by the averages 

 because the long time spent by the non-overtrained group is 

 the result of the inclusion of the rat Gl 9 which spent a great 

 deal of time in trying to remove the dressing from its head. 



Only one animal did not show evidence of the maze habit 

 after removal of the frontal portions of the brain. This animal 

 showed such an amount of muscular weakness, or apathy, "that the 

 running of the maze was not attempted by it even after the fash- 

 ion of an untrained animal. With this exception the tests gave 

 indisputable evidence of the retention of the habit after the 

 frontal portions of both hemispheres has been excised. More- 

 over, the evidence is more compelling because of some obvious 

 behavior disturbances in a number of the animals. Thus, it 

 has been reported of the second animal, Gl 9 that, although the 

 time for running the maze after the operation was greater than 

 in the training series its other behavior relating directly to the 



