424 



THE PIGMENT SYSTEM 



CHAP. 15 



which almost alone among green algae does not contain any chlorophyll b, 

 is also characterized by the production of oil instead of starch. A 

 review of algal families for primary starch production and chlorophyll h 

 content brought no striking confirmations of this hypothesis but also no 

 contradictions to it. Seybold then proceeded to investigate the chloro- 

 phyll composition of monocotyledons which produce no starch (e. g., 

 members of the Allium family) and found a deficiency in chlorophyll h 

 (while the ratio of [carotenol] : [carotene] and of [chlorophyll] : [carote- 

 noids] did not show systematic deviations from the usual average). 



Table 15.IX 

 Pigments of Several Monocotyledons 



Seybold suggested that, even in dicotyledons, the gradation in the 

 [a]:[b] ratio with light exposure, illustrated by table 15.VIII, may be 

 associated with a gradation in the capacity for starch synthesis. This 

 conclusion awaits confirmation by more extensive experimentation; even 

 if confirmed, it would not in itself disprove the earlier theory of Seybold 

 and Egle that the increased concentration of chlorophyll b is the result 

 of chromatic adaptation to weak bluish light, since heliophilic character 

 and absence of starch production may sometimes go hand in hand. 

 However, the adaptation theory would have to be discarded if one ac- 

 cepts also Seybold's suggestion that chlorophyll b does not partici- 

 pate in photosynthesis at all, but is a specific sensitizer for the photo- 

 chemical polymerization of sugars to starch; but (as mentioned on 

 page 150) we consider this suggestion highly implausible. 



3. Ontogenetic Adaptation of the Pigment System 



The capacity of individual organisms to adjust themselves to external 

 conditions is superimposed upon their hereditary inclination to produce 

 a certain pigment mixture. These individual adaptations extend to 

 both quantity and spectroscopic quahty of the pigments. As in the 

 case of phylogenetic adaptation, the most spectacular example is provided 

 by colored algae. Engelmann and Gaidukov (cf. Engelmann and 

 Gaidukov 1902, and Gaidukov 1903) found that the color of these 



