a. 
B.—-CHEMISTRY. 43 
In the solid form these products are micro-crystalline powders, bluish- 
black and greenish-black respectively. | They are accompanied by two 
non-nitrogenous yellow pigments, the unsaturated hydrocarbon, 
carrotene, C,,H,,, and its oxide, xanthophyll, C,,H,,0, both of which 
readily absorb oxygen and are allied to a third carrotinoid substance, 
fucoxanthin, ©,,H,;,O,, associated with them in brown alge and 
isolated in 1914. _ Based upon the experience indicated above, Will- 
stétter and his colleagues have examined upwards of 200 plants drawn 
from numerous classes of cryptogams and phanerogams. The leaf- 
green of these is identical, and the proportion of a to b almost invariably 
approaches 3 : 1 excepting in the brown alge, in which b is scarcely 
recognisable. 
This is not an occasion to follow, otherwise than in the barest out- 
line, the course of laboratory disintegration to which the chlorophyll 
molecules have been subjected by the controlled attack of alkalis and 
acids. The former agents reveal chlorophyll in the twofold character 
of a lactam and a dicarboxylic ester of methyl alcohol and phytol, an 
unsaturated primary aleohol, C,,H,,.OH, of which the constitution 
remains obscure in spite of detailed investigation of its derivatives; but 
the residual complex, representing two-thirds of the original molecule, 
has been carefully dissected. The various forms of this residual com: 
plex, when produced by the action of alkalis on chlorophyll, have 
been called ‘ phyllins ’; they are carboxylic acids of nitrogenous ring: 
systems, which retain magnesium in direct combination with nitrogen! 
The porphyrins are the corresponding products arising by the action of 
acids; they are carboxylic acids of the same nitrogenous ring-systems 
from which the magnesium has been removed. The phyllins and the 
porphyrins have alike been degraded to the crystallina base, stiopor- 
phyrin, ©,,H,,N,, into the composition of which four variously 
substituted pyrrole rings enter, probably as follows :— 
CH — CH 
| | 
CH,.C — CHyY. Ze C 
; DN Ne i] 
C.H,.C CD g& — CH 
C tnadeinend Yo 
C. H,.C —— CC Wat C.C.H, 
| ,NH HNC | 
CH,.C — C Cc C.CH, 
CH 
*Htioporphyrin, C,,H,,Ny 
It is this assemblage of substituted pyrroles which, according to 
present knowledge, is the basic principle also of the blood-pigment, in 
which iron plays the part of magnesium in chlorophyll. Fundamental 
as is the difference between hemoglobin and chlorophyll, relationship 
can be claimed through this connecting-iink, because the same com- 
pound, etioporphyrin, has» been produced from hemoporphyrin, 
C,,;H,,0,N,, which is thus its dicarboxylic acid. Hemoporphyrin 
arises from hematoporphyrin, C,,H,,0,N,, produced by the action of 
hydrobromic acid on hamin, C,,H,,0,N,FeCl, which in turn is 
detived by exchanging chlorine for hydroxyl in hematin 
F 2 
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