56 
the latter. On evaporating over the water bath and ad- 
ding water to the residue a yellow liquid was obtained, 
containing a colouring matter, the reactions of which were 
similar to those of the substance from elm leaves. No tannin, 
however, could be detected in the solution and this may 
serve to explain the fact that blades of grass, corn, &c., do 
not ultimately become brown in fading, but remain yellow. 
The portion of the residue after evaporation left undissolved 
by water, was green and fatty, and its solution in alcohol 
showed the absorption bands due to modified chlorophyll. 
These experiments leave the question of the nature and 
mode of formation of xanthophyll undecided. It may be 
one and the same substance in all leaves, or it may differ 
according to the source whence it is derived, it may be 
formed by the oxidation of chlorophyll, or it may pre-exist 
in the green leaf. I am inclined to think that it exists ready 
formed in the green leaf, but is not then seen on account 
of the far greater tinctorial powers of the chlorophyll 
present at the same time, and that it makes its appearance 
only when the chlorophyll has been decomposed, the sole 
trace left by the latter being the slight greenish tinge which 
all faded yellow leaves show more or less. The varying 
proportion of xanthophyll contained in green leaves would 
explain the fact, difficult to understand if we suppose it to 
be derived from chlorophyll, that some leaves assume a 
deep yellow colour in fading, while others remain of a pale 
yellow, and others again are almost colourless when they 
fall. 
I will now conclude, hoping, if I have not communicated 
anything strikingly new, that I may at least have succeeded 
in affording the meeting a few moments’ amusement. 
Bromley, Kent, 
10th December, 1881. 
