Schunck . — The Chemistry of Chlorophyll. 1 1 7 
phyll, as connected with its properties in general, I will simply 
record some thoughts and suggestions that have occurred to 
me relative to the purely chemical side of the question, putting 
entirely on one side all that relates to the purely physical 
properties of chlorophyll, to its colour for instance, and its 
consequent power of absorbing heat and light in a peculiar 
manner, properties which, though undoubtedly important, can 
only be profitably studied by the physicist. My remarks, 
possibly in themselves of little importance, may perhaps serve 
to stimulate further inquiry. 
In removing chlorophyll from the class of resins, where it 
had previously been placed, to that of colouring matters, 
Pelletier and Caventou undoubtedly took a step in advance ; 
using the phraseology of modern chemistry, they placed it in 
the aromatic series of carbon compounds. No general views 
of importance regarding the constitution of chlorophyll are 
met with before the time of Hoppe-Seyler, who thought that 
his chlorophyllan might be a substance belonging to the 
lecithin class, yielding like other lecithins glycerine-phosphoric 
acid and choline as products of decomposition, and in addition 
to these chlorophyllanic, and perhaps fatty acids. In what 
relation chlorophyllan stands to chlorophyll itself he does not 
state. Tschirch thought that chlorophyllan itself was a pro- 
duct of oxidation of chlorophyll, into which it might be re- 
converted by the reducing action of zinc powder, but whether 
the chlorophyll so regenerated was identical with the natural * 
colouring matter seems doubtful, Tschirch himself admitting 
that they differ in some respects. The lively green colour of 
the solutions of the compounds obtained in the manner I have 
described by bringing phyllocyanin, organic acids, and various 
metallic oxides together, a colour very nearly resembling that 
of true chlorophyll-solutions is so striking that, taken together 
with the resemblance between the absorption-spectra of some 
of these solutions and that of chlorophyll, one is almost led 
to suppose that chlorophyll had in some cases been actually 
reproduced from phyllocyanin. This is indeed true in a certain 
sense, I think, i.e. in every case, whatever acid or whatever 
