406 THE PIGMENT SYSTEM CHAP. 15 



these unicellular organisms belong to the first and some to the second 

 class. Heterocontae, Phaeophyceae, Rhodophyceae, Cyanophyceae, and 

 Diatomeae may be descendants of the first group of the fiagellates, while 

 Chlorophyceae and all the higher green plants may be genetically related 

 to the second group. 



Seybold (1941) noticed that green algae deficient in chlorophyll h do 

 not form starch as a direct assimilation product. Vaucheria, for example, 

 is known to store oil and not starch. A review of other algal classes 

 showed no direct contradictions to this rule. (Whenever starch was 

 found in 6-deficient colored algae, it could be interpreted, according to 

 Seybold, as a "secondary" product.) Seybold suggested that only 

 chlorophyll a participates in the synthesis of sugar, while chlorophyll 6 

 is a specific sensitizer for starch synthesis, a suggestion with which few 

 will agree. 



It has been asserted that at least some (and perhaps all) 6-deficient 

 colored algae contain another chlorophyll component, designated as 

 "chorofucin" by Sorby, and "chlorophyll 7" by Tswett. (Since the 

 nonexistence of a third chlorophyll component in leaves has now been 

 agreed upon, this compound may also be designated without ambiguity 

 as "chlorophyll c") The "third chlorophyll" was first observed by 

 Stokes in 1864 in extracts from brown algae, and its presence was later 

 confirmed by Sorby (1873) and Tswett (1906). Willstatter and Page 

 (1914) asserted, however, that it occurs only in extracts from algal 

 material which has been kept in storage — even if for only a short time — 

 and suggested that it is a decomposition product of chlorophyll a. 

 Wilschke (1914) and Dhere and Fontaine (1931) found, in extracts from 

 the brown alga Fucus, an absorption hand at 631 m^u, which could not 

 be attributed to either chlorophyll a or 6. A similar result was obtained 

 by Bachrach and Dhere (1931) with extracts from the diatom, Navicula. 

 Dhere and Fontaine also found an extra band in the fluorescence spectrum 

 of extracts from brown algae, even fresh ones, but this band was not 

 observed by Dhere and Raffy (1935) in living algae. This caused 

 Dhere to agree with Willstatter's hypothesis that "chlorophyll c" is a 

 post-mortem product. However, this concept was challenged by Strain 

 and Manning (1942^), who found that the absorption spectra of extracts 

 from diatoms {Nitzschia closterium) and brown algae (Fucus furcatus and 

 eight other species), prepared in many different ways, always show the 

 same deviation from the absorption spectrum of pure chlorophyll a. 

 The component responsible for this change was obtained in the pure 

 state by chromatographic separation, and proved to be a pale green 

 pigment with an absorption spectrum similar to that given by Tswett 

 forj' chlorophyll 7" and a fluorescence spectrum similar to that reported 

 for chlorofucin by Wilschke and Dhere and Fontaine. It is not identical 



