On the Colour of Leaves of Plants and their Autumnal Changes

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                                to the pink colouring matter.
It has already been stated, that the young, upper leaves 
of the Gloire de Dijon Rose are of an intensely dark red, with 
in some, glimpses of a little green colour. Under the microscope 
the colouring matter is seen to occupy the cells in the same 
way as in the other red leaves. An alcoholic solution was pre=
=pared from these leaves, but this instead of being, as in the 
geraniums of a reddish yellow tinge was a bright grass green.
Notwithstanding this however, the residue left after evaporation 
was for the most part bright red, but outside this red deposit 
was a circle of a green colour, while in the centre of the red 
residue was a round spot composed of yellow colouring matter.
The explanation of these differences will be given a little 
later on. The <s>cut portions <\s> single pieces of red leaf after the action of the 
alcohol were quite colourless.
Another plant of common occurrence in the Riviera and which 
has already been referred to, is the Castor Oil plant; the young 
shoots and leaves are of a dark, mahogany colour; the younger 
and smaller the leaf, the deeper the colour, the young stems 
and mid-ribs of the leaves being bluish red; both surfaces of the 
leaf are coloured, but the colour is confined to the superficial layer 
of cells, not continuously, but with intervals showing the usual 
green colour of the older leaves.
The alcoholic solution, like that obtained from the young 
leaves of the Gloire de Dijon Rose, was of a beautiful grass green 
colour, changing in the course of evaporation to a brilliant  carmine.
The dry residue presented the following characters; An outer green 
ring, an inner red ring and a central area or spot, having 
                            
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Manuscript details

Author
Arthur Hill Hassall
Reference
AP/69/1
Series
AP
Date
1892
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On the Colour of Leaves of Plants and their Autumnal Changes, 1892. From The Royal Society, AP/69/1

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