80 L. W. SACKETT 



his right hand, or their left hand if the experimenter reached 

 the food with his left hand. In other words, the response was 

 generally symmetrical with the environment. At the same 

 time, all tests and observations in this study indicate that the 

 untrained porcupine is in perfect bilateral symmetry. 



9. The habit, perfectly formed, of taking food with one par- 

 ticular hand may be broken very readily by the substitution 

 of the other hand so that no trace of the old habit remains. To 

 re-establish the old habit is almost as great a task as the initial 

 formation of the habit. This seems to indicate that "first 

 impression" is not an extremely important factor in the learn- 

 ing process of the porcupine. 



10. Porcupines may readily be trained to use one hand to 

 take one kind of food and the other to take another kind of 

 food and to change the hand as often as the food being offered 

 is changed. In this, there was definitized response to particular 

 and varied stimuli. In making this adaptation they w^re guided 

 by some form of visual stimuli — probably brightness of the 

 food morsels. 



11. Porcupines readily learn and operate puzzle-boxes of four 

 locks in a series. In doing so, each part was operated in the 

 simplest manner consistent with the general method which 

 chance success and repetition had formed into habit and the 

 whole series was carried through with a minimum of effort. 



12. No definite determinations have been made on the porcu- 

 pine's ability to discriminate tones of different pitch. Vocal- 

 izations of the species indicate a fairly wide range of tonal 

 discrimination. The cochlea is also very complex. Observa- 

 tion shows them responding more sensiti\Tly to sounds of low 

 vibration rate, such as rustling of leaves or the rumble of distant 

 voices. 



13. In the use of forms which were constructed to appeal to 

 the denning proclivities of the porcupine, these animals learned 

 to discriminate the circle from other forms presented pair-wise 

 and eventually to find it when it was presented six-wise. In 

 making the choice of the forms, only a part of the form was 

 ordinarily used as a basis for discrimination. There seemed to 

 be .some kind of rudimentary image of the circle sufficiently 

 definite to cause the animal to react ncgati\'cly to each of the 



