114 BOTANICAL GAZETTE [FEBRUARY 
Leaf pigments 
CHLOROPHYLL a AND b.—The amount of leaf pigments of Coleus 
was compared with the amount of leaf pigments in the lilac, accord- 
ing to the method given by WILLSTATTER and Stoxt (53). The 
ether extracts of the pigments were compared spectroscopically, 
and the amount of chlorophyll present in the lilac and in the Coleus 
was compared by the width of the absorption bands in the red 
end of the spectrum. In this comparison the band lying between 
the Fraunhofer lines B and C was used, since it was the most 
distinct. The extract of the Coleus leaves absorbed the rays from 
685.5 uu to 674.5 pu. The chlorophyll solution from the lilac 
leaves was then diluted until it gave an absorption band of the same 
width. It was found that the chlorophyll a and 6 content of the 
healthy green leaves of lilac was five times as great as the chloro- 
phyll content of the healthy green leaves of Coleus. Not even a 
trace of absorption in the red end of the spectrum was observed 
in the ether extract of the completely mottled leaves. 
The four leaf pigments (chlorophyll a and 6, carotin, and xantho- 
phyll) of green and completely mottled leaves of Coleus and of 
green leaves of lilac were then separated according to the method 
given by WILLSTATTER and STOLL,’ and the extractions tested 
spectroscopically to make sure of the purity of each extraction. 
The amount of each of the four pigments in the various leaves was 
then compared by means of a Schreiner colorimeter. The amount 
of chlorophyll a and 0b in the lilac leaves was taken as a standard, 
and the amount of green pigments in the Coleus leaves was com- 
pared with that of the lilac leaves. The writer realizes the limits 
of such a standard and regrets that there is not some stable dye or 
color which would serve as a basis for determining the exact amount 
of chlorophyll pigments in a leaf. The extraction of the pure 
pigments is a rather lengthy and expensive process, and when the 
pure pigments are once obtained some of them apparently do not 
keep well? By colorimetric comparison the lilac leaves were 
*A method for the quantitative estimation of the four pigments of green leaves 
will be published later. 
2 Preparation of these pigments, their keeping qualities, and some spectropho- 
tometric data will be published soon. 
