144 VEGETABLE PHYSIOLOGY 
chlorophyll by alcohol. It can be separated from the 
extract by appropriate means, and its solution yields the 
absorption spectrum represented below those of chlorophyll 
in fig. 84. Another pigment, Hrythrophyll, is present in 
thosa leaves which are found upon the trees in autumn. 
Like xanthophyll, it appears to be a product of the decom- 
position of chlorophyll, and it has a spectrum which differs 
from both the others. 
It is extremely difficult to say what is the chemical 
composition of chlorophyll, on account of the readiness with 
which it is decomposed. In all the processes which have 
been adopted for its extraction it undergoes decomposition, 
and consequently no definite conclusions as to its chemical 
nature can at present be arrived at. It can be made to 
yield definite crystals by appropriate methods of treatment 
after extraction, but it is probable that these crystals are 
a derivative of chlorophyll and not the pure pigment. 
Analyses of the crystals have been made by Gautier and by 
Hoppe-Seyler, who give them the following percentage 
compositions :— 
Gautier Hoppe-Seyler 
C 73°97 73°34 
H 9:8 9°72 
N 4:15 5°68 
O 10°33 9°54 
Ash 1:75 1:72 
According to Hoppe-Seyler the ash contains phosphorus 
and magnesium. 
From his analysis Gautier came to the conclusion 
that chlorophyll is related to the colouring matter of the 
bile ; Hoppe-Seyler considered, on the other hand, that it 
is a fatty body allied to lecithin. 
Except in the lowest unicellular plants, the chlorophyll 
is always attached to some form of protoplasmic body 
known as a plastid. These are small masses, of varying 
size and shape, which are embedded in the general cyto- 
