CANADA PORCUPINE 51 



other animals, however, does not justify the same assumption. 

 In the cases of Nos. 6 and 7, it is equally certain that there 

 was some form of reaction in which visual stimuli was the chief 

 factor. The tw^o sets of results are sufficiently similar to be 

 discussed as one problem. In reference to other controls, the 

 precautions by means of uniform paints and frequent washings 

 of the soiled forms have most certainly kept the relative bright- 

 ness of the forms well below the discrimination limen. As to 

 the possibility of the forms having particular markings by 

 which the porcupine might discriminate them, the reader is 

 refeiTed again to the many reversions and inversions of the 

 individual forms which was more than sufficient to complicate 

 and break up an}^ such associations. In the judgment of the 

 writer there remains but two questions legitimately open to 

 discussion: (a) Have the porcupines grasped the forms as a 

 whole or in part sufficient to give a perception of one dimen- 

 sional space? (b) Have they observed only the outline, only 

 the edge as a more or less regular line giving perception of one 

 dimensional space? Auxiliary to these is the other problem of 

 whether the discrimination is of the perceptual or conceptual 

 order ? 



As to the first question the author is skeptical. It is far 

 from certain that the animals have even seen a circle or a tri- 

 angle, as such, in one visual grasp. The fact that the forms 

 were necessarily large for this kind of work; that the animals 

 possess no binocular field of vision and above all that they are 

 probably myopic* in daylight for still objects makes perception 



* Note: April 23rd, almost 11 months after I began work with the porcupines 

 and nearly seven months after obtaining porcupine No. 7 this very interesting 

 incident occurred. No. 7 was feeding as usual in one of the side rooms in the barn 

 when a large, light gray cat looked around a partition and stood observing us from 

 a distance of about eight feet. Nothing but its head was visible. As the porcupine 

 turned in the course of the experiment so that the image of the cat might fall on 

 the periphery of his retina, he quilled with a suddenness which I never have seen 

 in any of them before, and scudded away to a corner of the room. When I looked 

 again the cat was still motionless but whether it had moved its head as the porcu- 

 pine turned in the experiment and thus gave No. 7 vision of a moving object or 

 whether the porcupine had perceived a still object at that distance can not be 

 certain. This difference in the behavior of the porcupine toward food stimulus 

 and enemies is significant. I have been told on reputable authority that a few 

 months after I had captured this animal, hunters took a wild cat from the same 

 locality in the mountain. Thus, we may safely surmise that No. 7 phyletically 

 and probably individually knew this feline enemy. Possibly if we were stimulat- 

 ing the porcupine with their arch enemies we should not be led to infer myopia. 

 But the fact still remains that the porcupine seems to be unable to perceive sig- 

 nificance in a situation as new as a piece of laboratory apparatus at a distance 

 of more than a few inches. 



