118 BOTANICAL GAZETTE [FEBRUARY 
pigments. Had Merver availed himself of methods of estimating 
the yellow pigments, he doubtless would have reported differently. 
Kout (30) has written extensively on carotin. He has shown 
that in Vicia Faba seedlings carotin forms and increases in the 
dark; in the light, at a low temperature, chlorophyll formation 
is suppressed, while the carotin increases; increase of light and 
temperature accelerates chlorophyll formation. Working with 
several species of plants, he concluded that etiolated plant organs 
owe their color almost exclusively to carotin. When some etiolated 
plants greened, the carotin content was found to increase sometimes 
as much as 125 per cent, and in all cases was found to increase to 
some extent. He did not believe that chlorophyll was formed at 
the expense of the carotin, however, nor did he think the chloro- 
phyll was changed to carotin in autumnal coloration. His experi- 
ments on coloration led him to conclude that the carotin content 
(evidently including carotin and xanthophyll) of the leaves 
increases. His results show that the carotin content of old leaves 
of Sambucus nigra is to the carotin content of young leaves of the 
same plant as 183:170. Color changes which he describes are 
very similar to those described by MEYER in autumnal yellowing. 
STOKLASA, SEBOR, and SENFT (47) believe that the autumnal 
changes of color depend on the hydrolytic fission of chlorophyll 
and the formation of phaeophytin and phosphatides; these sub- 
stances, which themselves have a brownish color, allow the red 
and yellow of carotin and of xanthophyll to appear. The colorless 
lecithin and choline derivatives are not combined with chlorophyll, 
but are merely admixed and possibly intimately associated with 
the chlorolecithins. The writer has shown that the yellow pig- 
ments in Coleus greatly increase as the leaf mottles. The yellow 
pigments are not simply left behind when the other pigments are 
translocated, but are being continually formed. 
WILLSTATTER stated that the proportion of chlorophyll @ and 6 
to the yellow pigments was 3.07 to 1 in sun leaves, while in shade 
leaves it was 4.68-6 to 1. IwANowskI (22) found that less chloro- 
phyll was broken up by light when the yellow pigments were in 
greater concentration. He concluded that the protective action 
of the yellow pigments could no longer be doubted. The yellow 
