THE LEAVES 69 



objects, such as the sugar beet, or large fruits, where 

 they could not possibly be of any use whatever. 



81. Characteristics of red and blue colors. It 

 has been shown in 66 that the red color of a leaf 

 of coleus may be extracted by water, and it is a 

 matter of common experience that the colors of fruits 

 are easily obtained in this way. If red coloring 

 matter is examined in the same manner as chloro- 

 phyl, it will be found that it absorbs different rays 

 of light than those taken up by the green pigment. 



82. Red color as a shield. A great many species 

 are furnished with a layer of red color on the upper 

 side of the leaf. This absorbs some of the light 

 which strikes the leaf, and a diminished amount is 

 allowed to fall upon the delicate green coloring 

 matter below. The action of the red then would 

 be like the slats of a shutter, which permit only a 

 part of the rays to shine through. The presence 

 of the red would be beneficial to leaves exposed to a 

 degree of sunlight stronger than they are otherwise 

 adapted to bear. 



83. Red color as a heat producer. The rays of 

 light that are taken up by the red and blue colors 



