178 NATURAL SCIENCE [September 
Now, although Mr Etard has, by virtue of masterly analytical 
skill, succeeded in separating certain distinct green bodies occurring 
in the same species, which seem to respond to a definite chemical 
composition, it is not so clear that the question as to what chloro- 
phyll itself really is has been finally settled. ‘The grand difficulty 
is to decide definitely whether chlorophyll is (like carotin) a solid 
substance in itself and present in such quantity as to allow of its 
being separated and withdrawn purely and simply from the other 
constituents of the leaf; or whether it exists therein in exceedingly 
minute quantity only (like that of a dye fixed on a vegetable fibre), 
and inseparable therefrom save by means which bleach and destroy 
it irrevocably? It is evident that if the former alternative be 
accepted, then by simply absorbing the green pigment by animal 
charcoal from the ‘ chlorophyll, it will still retain its physical and 
chemical characters unchanged; if the latter be adopted, the same 
absorption will completely destroy only the colouring matter as such. 
Unfortunately it is absolutely impossible to tackle the question 
on these grounds or in this fashion, for the simple reason that no 
solvent at present known extracts chlorophyll, ze. the pigment, 
purely and solely from the leaf; it is invariably conjoined with 
fats, waxes, resins, etc., and even subsequent exhaustive treatment 
with a series of different solvents does not eventually effect a com- 
plete purification. Such being the case, we must rest content with 
the results and effects of close application and a prolonged experi- 
ence, feeling assured that in the course of time views and vistas 
will open, leading to a correct apprehension of the subject. One of 
these views may now be exploited for the edification of the reader. 
Microscopic observation of the living leaf reveals that the 
chlorophyll granules are individually independent globules of dense 
protoplasm without proper walls plunged in the midst of the funda- 
mental protoplasm and tinged by the green matter, their form and 
size remaining unaltered when extracted by ether, etc. Protoplasm 
itself is of course insoluble in the solvents which readily dissolve 
chlorophyll, but it is always accompanied by fatty matter of free 
formation which doubtless is one of the products of assimilation. 
Starch also, although not invariably present, very commonly occurs 
in these corpuscles ; and Belzung seems to think that its presence is 
necessary for the formation of the green pigment—an opinion which 
I am disposed to dispute. In addition, however, to starch and fat, 
the occurrence of which is sufficiently palpable, it would be absurd 
to imagine that other bodies are not evolved in quantities more or 
less minute during the career of the tremendous vital energy exerted 
by the living protoplasm. Tremendous certainly it must be at the 
actual moment of its outcome, but perhaps for that very reason 
- essentially frail and subject to degradation and decay. - Hence arise 
