IQO 'Journal of Comparative Neurology and Psychology. 



errors, and so on. The normal behavior in learning the maze was first observed. 

 Nineteen normal rats were used for this purpose. 



Tests were then made to determine the principal sense organs used in learning 

 the maze. Normal rats which had previously learned the maze in the light, were 

 tested with the maze in the darkness. All the rats with one exception, ran the maze 

 perfectly in the dark. Normal animals were then allowed to learn the maze in the 

 dark from the beginning. Their records were quite normal. It was found that 

 animals trained to the maze in the light can run the maze almost perfectly after 

 both eyeballs have been extirpated. Likewise untrained rats, with both eyeballs 

 removed, can learn the maze in normal time. 



Animals without olfactory bulbs learn the maze in normal time, two of our 

 animals making phenomenal records. These anosmic animals after being trained 

 to the maze in the light are not at a loss if forced to run the maze in the dark. 



From further experiments, which we shall not report in detail, it becomes evident 

 that neither auditory sensations nor cutaneous sensations set up in the drum mem- 

 brane by the changes in the pressure of the various air columns in the maze play a 

 part in the formation of this association. Likewise it is improbable that the discrimi- 

 nation of the correct turns in the maze is effected by means of differences in the 

 contactvaluesof the various parts of the floor of the maze. The vibrissae, which are 

 probably used in the beginning of the association, are not used after the association 

 has been thoroughly established; for if after their removal a short period of adapta- 

 tion is allowed the rats in their living cages, no disturbance in their reactions is 

 noticeable when they are forced to run the maze. The correct turns are likewise 

 not made upon the basis of any possible difference in the temperature in the various 

 places in the maze. Differences in the pressure of the air columns do not form the 

 basis of the discrimination for changing the air pressure does not disturb the rats. 



It is of interest to note that the simple turning of the maze through the angles 

 of 45°, 90°, etc., badly disturbed both the normal and the defective animals for the 

 first three or four trips after the change was made. The method adopted in this 

 case was as follows: The animals, e.g., were allowed to learn the maze with the 

 entrance south; after they had become thoroughly familiar with it in this position 

 the entrance was placed east. Now, although the relations of the turns within the 

 maze are exactly the same as with tlie entrance south, the animals are confused. 

 No explanation of this is offered at present. 



Summarizing the results obtained from this series of experiments, we may say that 

 neither visual, auditory nor tactual sensations furnish the animal with the cue for 

 making the correct turns in the maze. The final conclusion is that kinaesthetic and 

 organic sensations are the principal sensory factors in this association. A suggestion 

 as to how the kinaesthetic sensations are "controlled" is offered. 



This paper is to appear soon as a monograph supplement to the Psychological 

 Review. 



Habit Formation in the Starfish. By H. S. Jennings. 



An account of experiments showing that by a course of training the starfish may 

 be induced to use habitually a certain pair of rays on which to turn in the righting 

 reaction. The habit lasted in certain cases three or four days. 



Modifiability of Behavior in the Dancing Mouse. By R. M. Yerkes. 



Visual discrimination tests show that the dancer avoids a disagreeable stimulus 



