THE SUMMIT OF THE YEARS 



to change colors; he glued the wings of the male to 

 the female and vice versa, and found that they mated 

 just the same. The laboratory experimentalists 

 ought to be able to throw light upon these questions. 



Elaborate experiments have already been made 

 to test the color-sense of certain birds, the Eng- 

 lish sparrow, the cowbird, the pigeon, and also 

 such animals as the raccoon and the monkey, with 

 the result that these animals do appear to dis- 

 criminate colors. But there always remains the 

 question: Are the animals guided in such cases by 

 a sense of color as we have it, or merely by a sense 

 of different degrees of brightness? A person who is 

 color-blind sees the different colors as varying shades 

 of gray, and for aught we know it is the same with 

 the animals: in selecting, say, blue or green, they 

 may only be selecting different shades of gray. 



I should like also to see our experimentalists test 

 the musical sense of birds : are they tone-deaf in the 

 sense that they are probably color-blind? Is the 

 divinely harmonious strain of the hermit thrush, 

 for instance, lost upon the ears of its mate and upon 

 its own ears? Does the rollicking and hilarious strain 

 of the bobolink count for nothing in its life? From 

 the apparent indifference of the female song-birds to 

 the musical performances of their mates, one would 

 say that the strains of the males fall upon deaf ears. 

 When the cock in the poultry-yard crows, the hens 

 shake their heads as if the sound annoyed them. The 

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