WHA T ANIMALS SEE 1 29 



imprisonment, are sufficiently remarkable ; but Dr 

 Harley also kept an accurate record of his impressions 

 when he at last looked again upon the light, after 

 the supreme moment at which he satisfied himself 

 that he was not blind, but could see. He found 

 that in the nine months* darkness his eyes had lost 

 all sense of colour. The world was black, white, 

 and grey. They had also lost the sense of distance. 

 His brain interpreted the picture wrongly. His 

 hand did not touch the object meant to be grasped. 

 Practice soon remedied the last induced defect of 

 sight. Experiment with skeins of various-coloured 

 wool, in the presence of one who had the normal 

 powers of colour-vision, restored the first. 



From this personal record, it may be gathered that 

 as the trained human eye has to learn, and might 

 lose, the sense of colour, so the animal brain, which 

 receives little or no training of this kind, may in 

 many cases be unaware of the colours which the eye 

 presents for recognition. We have no power of 

 determining this by simple tests, as in the case of 

 human beings. But there is little positive evidence 

 that the larger quadrupeds, oxen, deer, the felidas, 

 or dogs, have much sense of colour ; and their power 

 of vision in its wider sense varies so greatly in 

 different species as to suggest that the mental factor 

 in sight is often so little exerted for the main 



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