CHAPTER II 



THE PREVALENCE OF GREEN COLOR IN PLANTS, AND 

 THE REASON WHY IT EXISTS 



Chlorophyll and Photosynthesis 



manifold are the works displayed in the world of 

 living plants, that to one who seeks some tie to bind 

 them all into a single natural group they seem at first to 

 present only an endless diversity. They do in fact 

 exhibit every possible gradation and variation; in size, from the 

 stately Sequoia of the Sierras, or the giant Eucalyptus of Aus- 

 tralia, towering high above all other living things and mighty in 

 girth, down to the humblest weed of the wayside ; in form, from 

 the graceful tree with its spray of twigs and myriad leaves to the 

 simplest sea-born plant whose life is wholly encompassed within a 

 miniature globe : in color, from the quiet green of the forest to the 

 brilliant hues of flowers, sea-mosses, or mushrooms: in texture, 

 from the ivory-hard seeds of palms to the jelly-soft fronds of 

 some seaweeds ; in habit, from the independent life of the mightiest 

 trees in the woods to the parasitic existence of a deadly germ of 

 disease within the body of man. Nowhere among these features, 

 nor j'et among any others that we know, can we find a single 

 one which applies to all plants. What is it then which binds all 

 of this heterogeneous assemblage into a single natural group? 



Failing to find any one feature conmion to all kinds of plants, 

 a scientifically-minded inquirer would next turn to ask what 

 feature prevails most widely among them. If one marshals 

 before his mental vision all of the great groups, from the flowering 

 trees to the microscopical germs, and centers observation upon 



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