INFLUENCE OF DIFFERENT FACTORS ON PIGMENT FORMATION 431 



the carotenols in chromatograms of pigments from squash seeds. Ac- 

 cording to Seybold and Egle, the carotenols in etiolated seedlings are 

 developed in white light more quickly than are the carotenes. Rudolph 

 (1934) and Simonis (1938) found that the carotenoids are formed in 

 blue light more rapidly than in red light; again, as in the case of chloro- 

 phyll, this might be due either to the position of the absorption bands 

 of the "precursors," from which the carotenoids are formed, or to an 

 " autosensitization " by the pigments themselves. Simonis found that, 

 in Elodea grown in red light, the ratio of ([a] + [b]):([x] + [c]) is 

 23% larger than in a similar plant grown in blue light. Strott (1938) 

 disagreed with Rudolph and Simonis, and asserted that not only chloro- 

 phyll but also the carotenoids are formed in red light more efficiently 

 than in blud light of the same intensity. 



The chemical nature of the processes which lead to the pigment formation is a 

 matter of conjecture. It was mentioned on page 404 that Preisser first assumed, a hun- 

 dred years ago, that chlorophyll is formed by oxidation, and Lubimenko (1928) suggested 

 that the formation and decay of pigments in green leaves is connected with changes in 

 the oxidation-reduction potential. Lubimenko found a steady increase in "peroxi- 

 dase activity" (?) of leaves with age, and considered this development as character- 

 istic of the oxidation state of the cell. At first, in young leaves, this activity is low, 

 and the pigment system is in an almost colorless, "reduced," state; later, the activity 

 increases, and the pigments pass one after another into the colored, "oxidized," state; 

 in autumn, the pigments are oxidized further and are converted into colorless products. 

 The stationary concentration of pigments in summer leaves corresponds to a certain 

 favorable "intensity of oxidation processes," which strikes the balance between the 

 rates of oxidation of a chlorophyll precursor to chlorophyll and of chlorophyll to a 

 colorless oxidation product. This balance is maintained, according to Lubimenko, by 

 a "protective reducing substance," allegedly present in the chloroplasts, which he calls 

 "antioxidase." 



Lubimenko's picture of a continuous oxidation process, in which the colored pig- 

 ments form a transient stage, as well as his assumptions concerning the functions of 

 the colorless leucophyll and the pigments chlorophyllogen and protochlorophyll (illus- 

 trated by the scheme on page 404), may be plausible, but have as yet not much experi- 

 mental foundation. 



It was mentioned on page 405 that, if protochlorophyll is a precursor of chlorophyll 

 (which is by no means certain), the last stage in chlorophyll synthesis is a reduction 

 rather than oxidation. 



(d) Heredihj 



Albinism is an hereditary characteristic subject to the laws of Mendel. 

 It would lead us too far to discuss here the relation of chlorophyll de- 

 ficiency to heredity. We may refer, however, to the work of von Euler 

 and coworkers (1929-1935), who found a close relationship between the 

 inheritance of chlorophyll and of catalase. Chlorophyll-deficient mu- 

 tants have been regularl}^ found to be catalase-deficient as well. A 

 certain, but less uniform, relationship apparently exists also between the 

 inheritance of chlorophyll and of the carotenoids. 



