RETENTION OF HABITS BY THE RAT 17 



maze was "retained. The time variation (lengthening) was due 

 entirely to changes in its physical condition other than those 

 necessarily related to its maze activities. That this is so will 

 be realized when it is remembered that the delays were made up 

 of periods of scratching its head-dressing and of long stuporous 

 or apathetic pauses. In the fourth animal the sensibility of 

 the vibrissae was decreased, perhaps they were anesthetic, and 

 the short times for running the maze after the operation are 

 especially noteworthy. The twelfth and thirteenth animals 

 were weak and spastic, and exhibited abnormal reactions in 

 connection with the food dish, but both managed to find the 

 correct path quite promptly. The time for the first fifteen 

 trials of the thirteenth animal, G2 <f , after operation was only 

 slightly less than that of the corresponding period of training, 

 but the long stuporous pauses account for much of the time that 

 was taken. 



As a whole, therefore, the experiments show that in the white 

 rat the removal of large parts of the frontal portions of the brain 

 does ngt greatly interfere with a learned reaction. This is the 

 more remarkable since it seems probable that the so-called motor 

 area is in that region and that in most, if not all, of the cases 

 there was a destruction or abolition of the motor connections. 

 While it can not be concluded with certainty, it seems likely 

 that the motor derangements which were exhibited by many 

 of the rats were due to the interference with the normal ef- 

 ferent impulses and not to the general anemia (from the hemor- 

 rhage of the operation). Some of the animals also showed ob- 

 vious disturbances of sensibility, the observations indicating 

 that in some the stimuli to the vibrissae and olfactory stimuli 

 did not give normal effects. In view of the importance of these 

 two forms of sensibility in the rat's reactions, we are led to 

 wonder whether these retain their predominance in the animal's 

 learned activities, or are replaced by other forms of sensibility, 

 such as the general kinesthetic. Although the results give plain 

 evidence of non-interference (relative, to be sure) with learned 

 reactions when the frontal portions of the brain have been de- 

 stroyed they also suggest that the habit reaction is not neces- 



PBYCHOBIOLOGT, VOL. I, NO. 



