CHAPTER V. 

 COLOR-SENSE. 



The color-sense of mammals has been investigated by 

 experiments and by a study of their natural history. I 

 propose briefly to summarize the conclusions these investi- 

 gations have led to, discuss the way in which the color- 

 sense has been influenced by the adoption of arboreal life, 

 and endeavor to correlate its varying degrees of acuteness 

 with the different anatomical appearances met with in the 

 percipient end-organs of the retina. 



Many carefully thought-out experiments have been per- 

 formed to test the chromatic sense in mammals, and in some 

 elaborate precautions have been taken to exclude any fallacy 

 which might be occasioned by unequal degrees of luminosity. 

 These experiments have mostly been applied to dogs and 

 monkeys. The details of them will be found well epitomized 

 in Parsons' 17 book on Color Vision. It will suffice for my 

 purpose here to quote only the results obtained. 



Graber 38 found that the pig and the dog could distinguish 

 between blue and red, showing a distinct preference for the 

 former; it is, however, doubtful if this preference was not 

 due to brightness rather than color. 



Kalischer 39 came to the conclusion, from feeding experi- 

 ments he carried out on dogs, that there is no doubt of their 

 ability to perceive differences of hue as well as differences 

 of brightness; but that there exist considerable differences 

 in their sensibility to color. 



