Schunck . — The Chemistry of Chlorophyll . 67 
on vegetable physiology the term chlorophyll is sometimes 
applied to the complex of substances contained in living green 
cells which take part in the process of assimilation, and of 
which the colouring matter constitutes a portion ; and chemists, 
following the example of physiologists in giving a name to 
the whole which should have been confined to one part, have 
been led to ascribe to chlorophyll properties which no mere 
chemical substance can possibly possess. Only a few years ago 
Regnard 1 endeavoured to prove that chlorophyll when dissolved 
in alcohol, and therefore completely out of the range of influ- 
ences prevailing in the vegetable cell, was able to decompose 
carbonic acid and evolve oxygen on exposure to sun-light. 
Pringsheim 2 has shown that Regnard’s conclusions were er- 
roneous. The proof was, however, hardly needed, since no 
chemist need be told that it is impossible for a substance like 
chlorophyll, after separation from the organism of which it 
once formed a part, to effect the decomposition of carbonic 
acid with evolution of oxygen, unless indeed we suppose that 
it carries with it into solution a portion of the vitality of its 
original surroundings, which I imagine no physiologist would 
allow to be possible. 
I may say then, in order to avoid misconception, that in 
using the term chlorophyll I mean simply the substance — or 
it may be mixture of substances — to which the pure green 
colour of ordinary healthy leaves and other vegetable organs 
is due. 
Attempts to isolate Chlorophyll. 
In endeavouring to separate chlorophyll from the impurities 
accompanying it in the extracts prepared from leaves, the 
older chemists assumed that chlorophyll was a body of very 
stable character, and they consequently, for the most part, 
employed strong acids as a means of purification. Now chlo- 
1 Comptes Rendus, Dec. 14, 1885. 
2 Ber. d. Deutschen Bot. Gesellschaft, 1886, IV. n. 
