38 The Living Plant 



pass through as waste; and these of course are the ones which 

 come to our eyes. Now these waste rays include the entire green 

 light, which gives the principal color, together with all of the yel- 

 low, which, mixing with the green, gives thereto the characteristic 

 yellowish tinge which chlorophyll always shows. As to the re- 

 maining rays, they happen to form complementary pairs; thus 

 the bit of red and bit of green-blue form one pair, while the orange 

 and unabsorbed blue form another; and as complementary colors 

 (with lights) always give white or gray, these minor rays thus 

 neutralize one another so far as color is concerned, and do not at 

 all affect the positive yellow-green. If it had happened that, in- 

 stead of red and blue, the red and green had been the useful rays, 

 then chlorophyll, and all vegetation, would have looked blue; and 

 had green and blue been the useful kinds, then all vegetation 

 would have looked red. The greenness of vegetation is simplj^ 

 the wastage of that part of the white light of the sun which is not 

 needed in photosynthesis. 



In the early part of this chapter it was mentioned that many 

 leaves of a red color really possess chlorophyll, which becomes 

 visible when the red is removed by suitable solvents. This is 

 true of the seaweeds, the red and brown colors of which are due 

 to special pigments in the same grains with the chlorophyll; and 

 there is good reason for believing that these colors bear a relation 

 to the light conditions under which those seaweeds live, aiding 

 the chlorophyll to utilize the sunlight as altered by its filtration 

 through water. The case in the more familiar red plants of garden 

 and field, however, is different. The colors in the foliage plants 

 (Coleus, Copper Beeches, Japanese Maples) as well as in some 

 vegetables (Beet, Red Cabbage), is a product of enormous in- 

 tensification under cultivation ; but in all cases the wild ancestors 

 of these plants possessed some red color to begin with. This red, 

 indeed, is fairly common in wild plants, where it shows especially 

 in veins, petioles, nodes, or the under sides of leaves, and in the 

 stigmas of many wind-pollinated flowers. It reaches, however, 



