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1905] BRIEFER ARTICLES 303 
beaker to exclude all light during the extraction of the chlorophyll. In 
order to eliminate individual peculiarities, each experiment was done in 
duplicate for two different plants of each species studied. The time 
required for extraction of the chlorophyll from leaves of different species 
varied widely and is recorded for each case in the table following. Except 
where otherwise stated, half-grown leaves were used, as in most cases 
they yield the best solution in the shortest time. 
It was found that the transparency of living leaves was increased if the 
air was driven from the intercellular spaces and its place was taken by 
water. Accordingly in these experiments the leaves were put in water 
under the air pump for half an hour and examined at once. If they are 
allowed to stand in water for an hour, leaves like Pelargonium, Begonia, 
Oxalis, etc., show the characteristic spectrurn of incipient decomposition 
of chlorophyll. In the table the spectrum of a single leaf is given in each 
case 
The spectra were observed by a Kohl spectroscope, Hoffman form, 
mith a comparison prism; one which is ample for all educational work. 
The Welsbach light was used. 
Asis well known, chlorophyll when examined by means of a spectroscope 
shows in all seven distinct absorption bands which are usually designated 
by the Roman numerals. I is 4 broad black band in the red; II is a 
‘artow gray band in the red, near the orange; III is a gray band in the 
srange near the yellow; IV is a dark band in the middle of the green; V, 
VI, and VIE are broad black bands in the blue, usually absorbing it to 
such a degree that with a few exceptions they can be seen separately only 
it a very thin layer of a dilute solution, These seven bands are never all 
present at one time. 
_1n the following table the letter d means the band is dark; that it is 
oa ul that itis very faint; and o that it is absent. Where the spect 
are 5g leaf differs from that of the chlorophyll solution its differences 
tion of ape by the bracketed letters. The time required for the extrac- 
the asiosit chlorophy ll is given in minutes. The thickness of the layer of 
Solution in each case was 15™™, ‘Typical green” means the average 
; nged color of chlorophyll. 
ing a“ a table it will be seen that certain leaves are described as yield- 
acid $3 w-green solution. In all these cases the solution gives an 
fhe on With litmus paper and the spectrum is of a distinct character 
a of the other leaves. ‘These facts, with others developed in the 
Classes of this study, show that we must distinguish between two distinct 
of chlorophyll spectra: the ‘normal chlorophyll spectrum” show- 
