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 hlue 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. Bed 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. Bed color as a heat producer. — The rays of 

 light that are taken up by the red and blue colors 



