82 LUTHER BURBANK 



when hybridizing experiments are performed,, 

 that at least give clues to the story of the evolu- 

 tion of color. 



Analogies drawn from the study of the spec- 

 trum are also of aid, in connection with these 

 practical observations, in developing theories of 

 the philosophy of flower coloration, which, if 

 they cannot be said to be definite, have at 

 least a large element of plausibility and are 

 full of interest. 



THE PHYSICAL BASIS OF COLOR 



It has even been suggested that the earlier 

 forms of vegetation were probably red in color 

 where now the leaf structures in general are uni- 

 versally green; the basis for this belief being the 

 observed manner of reaction between plants of 

 green foliage and those of red foliage when hy- 

 bridized, the fact that sea weeds are usually red, 

 and the further fact that young vegetation, such 

 as the buds of trees in the spring, is very gener- 

 ally red in color, the subsequent greenness being 

 due to the development of chlorophyll granules. 



Just why the cholorophyll granule is green is 

 of course only matter for conjecture. But it is 

 obvious that this is the ideal color for this pur- 

 pose, otherwise it would not have been so uni- 

 versally adopted. 



