3i6 THE CHLOROPHYLLS AND THE CAROTINOIDS 



complete absence of light. While various opinions have been expressed re- 

 garding the role which these pigments play in photosynthesis as yet no con- 

 vincing evidence has been discovered that they play any part at all. 



3S0 400 420 440 460 460 500 

 WAVE LENGTHS IN MILLIMICRONS 



Fig. 82. Absorption spectrum of [3-carotene in ether-alcohol solution. 

 Data of Miller et al. (1935). 



Relative Quantities of the Chloroplast Pigments Present in Green 

 Leaves. — The chlorophylls are present in green leaves in greater quantity 

 than the carotinoids. This fact is illustrated by the data in Table 28 which 

 shows the absolute quantities of each of the four chloroplast pigments in the 

 leaves of the European elder. 



TABLE 28 QUANTITY OF EACH CHLOROPLAST PIGMENT IN LEAVES OF THE EUROPEAN ELDER 



{Sambucus nigra) in july expressed in grams per kilogram of fresh leaves 

 (data of willstatter and stoll, 191 8). 



Of greater significance from a biological standpoint are the molecular 

 proportions of these several pigments in the leaves. Since the molecules of 



