346 POPULAR SCIENCE MONTHLY. 



this tendency seems to be a fundamental instinct manifested by even 

 the youngest mammals and is evidently of vital importance for their 

 preservation. 



Cat. The cat on which I am able to report was not in good condi- 

 tion after she became suddenly blind in both eyes, and lived but a few 

 days, or I should have been able to note more fully whether her psychic 

 state had been modified by experience. 



When put down on the floor she moved about in a slow and appar- 

 ently cautious way, and, though plainly perfectly blind, when she came 

 near objects she touched them only slightly. In this the whiskers 

 evidently served a good purpose, as was also observed in the rodents. 

 When one made a noise on the floor as by tramping with the feet, puss 

 invariably moved towards the sound, and so perfectly that by walking 

 about one could cause her to describe complicated figures, from which 

 and other observations I conclude that she had become a mere reflex 

 mechanism worked by the most prominent stimuli of the moment from 

 the external world. When she came to a wall, and especially a corner, 

 she stopped and sometimes lay down showing that the 'puss in the 

 corner ' tendency has a deep foundation, for I am inclined to believe that 

 this animal was not conscious in the true sense of the term. This cat 

 had become blind owing to a hemorrhage into the optic thalamus of 

 the brain and lived but a few days afterwards. 



I have not reported any other cases in this paper in which there 

 were brain lesions, the discussion being too complicated for my present 

 purpose. That the cat was guided purely reflexly by sounds was evident 

 from the fact that when one stood on a table and tramped as before, 

 puss underneath the table was soon brought to a standstill just below 

 the source of the sounds. Such a remarkable case of guidance reflexly 

 by the ear I had not seen before, and it proved very instructive to me. 



Dog. Of the blind dogs I have observed I shall refer to but one. 

 He was a cross-bred skye terrier and formed one of a litter kept in a room 

 in the college basement. He became totally blind when between two and 

 three months old. After this he soon changed greatly in disposition; 

 he, like the rats, seemed to revert to a sort of feral condition. He 

 would on the entrance of any one into the room hide, and when 

 approached would bite savagely at the extended hand ; in fact, in order 

 to catch him it was necessary to throw a sack or some such object over 

 him. He had gnawed away the legs on which Ms cage stood and to 

 which he was chained for a time. 



This dog seemed to be at least equal in intelligence to the other 

 members of the litter, his companions. So far as the objects in the 

 room that had a stable situation were concerned, he was perfectly 

 oriented, but if a new object was laid down he would run against it and 



