170 LIGHT, VEGETATION AND CHLOROPHYLL | 



Fig. II, 2. Absorption spectrum of the chlorophyll pigments. 



1, Whole chlorophyll; 2, Chlorophyll-a; 3, Chlorophyll-6; 



4, Carotene; 5, Xanthophyll 



especially in natural conditions. The active period, at least, 

 seems to be extremely short, since the average life of excited 

 chlorophyll has been estimated at 8 x 10-^ to 8 x 10-^^ second. 



The Action of Chlorophyll 



Chlorophyll seems to be the only pigment which enters 

 into photosynthesis, for it is the only one in which fluorescence 



