154 PROBLEMS OF BIRD LIFE. 



visibility of the three potatoes was entirely due to the coloring 

 of the under side, and Mr. Thayer was asked to color the middle 

 one like the two others in order that the effect might be 

 observed. Mr. Thayer complied with the request, painting 

 the under side of the middle potato white, and shading the 

 white up into the sides as in the case of the others. The effect 

 was almost magical. The middle potato at once disappeared 

 from view. A similar experiment was tried on the lawn. Two 

 potatoes were painted green to resemble the green of the grass 

 above which they were suspended. One was painted white on 

 the under side and at once became invisible when viewed from 

 a little distance, while the other showed plainly and seemed 

 very dark, the shadow, superadded to the green of the under 

 side, making it remarkably conspicuous. The experiments 

 were an overwhelming success." 



Try this experiment yourself and then notice how almost 

 invariable is this law of gradation by which Nature helps the 

 birds and beasts to escape detection, however gayly they are 

 colored. 



