1884.] 
and on the Assimilation of Carbon. 339 
sorbing strata. The absorption-specTrum of an alcoholic 
solution of chlorophyll is given by way of comparison. 
If we disregard the more highly refractive portions we 
find in the speCtrum of a leaf only the band I., as broad as 
the bands II., III., and IV. appear in the spedtrum of the 
solution. If we superimpose three leaves upon each other, 
I. becomes considerably broader than in the spedtrum of 
the solution, II. and III. appear faintly indicated, whilst IV. 
is still wanting. If we use five leaves, I. appears twice as 
broad as in the solution, whilst IV. comes up as a faint 
shade. With six or seven leaves it becomes more distindt, 
but disappears again in the spedtrum of eight or nine 
leaves. 
The speCtrum of living leaves is thus essentially distin- 
guished from the speCtrum of the solutions of chlorophyll 
by the comparative feebleness of II. and III., and by the 
quite rudimentary character of IV. These faCts show that 
the chlorophyll of solutions is chemically not identical with 
the chlorophyll of living leaves. In other words, the latter, 
when taken up by any solvent, always undergoes a chemical 
change. Comparative experiments show that the effeCt of 
treating chlorophyll with a weak acid consists mainly in an 
increase of the strength of the band IV. Hence we are led 
to the conclusion that chlorophyll, as it exists in solutions, 
corresponds chemically to chlorophyll modified by acids. 
The difference between these two kinds of chlorophyll, as 
observed in the absorption maxima, may be traced also in 
the minima, which lie between the wave-lengths 720 — 700 
in the extreme red, and between 560 — 540 in the green. In 
the absorption-spedtrum of leaves the red did not disappear 
until the light had been passed through a stratum of sixteen 
leaves. The green was perceptible even through a layer 
of eighteen leaves, whilst it is more strongly absorbed by 
concentrated solutions. 
Though Dr. Reinke comes, in the points above mentioned, 
in collision with the results of earlier experimentalists, yet, 
as regards the fluorescence of the chlorophyll of the living 
cell, he agrees with the majority of observers. He finds the 
chlorophyll of living leaves non-fluorescent, whilst, as is 
well known, solutions of chlorophyll display a very fine red 
fluorescence. Reinke explains this fadt by the consideration 
that the chlorophyll in the leaves does not exist in a state of 
solution. The absence of fluorescence depends, conse- 
quently, on the state of aggregation of the chlorophyll. 
That its condition in this respedt is decisive may be learnt 
from the following experiment ; — Chlorophyll obtained from 
