STRUCTURE. 55 
and the varying manner in which they are affected 
by chemical influences, including the varying 
effects of the influence of light upon them, 
impress us with that exquisite sense of colour 
which lends so great a charm to flowers. So 
far as science has yet been able to comprehend 
this subject—for there is very much which 
still remains undiscovered and undetermined— 
it has been found that there are not less than 
seven substances of the nature of chlorophyll 
existing in differing plants; that these substances 
have distinct colouring capacities, and produce by 
commixture in varying proportions the exquisite 
shades and variations of colour in the plant 
world. It will therefore be desirable, as the word 
chlorophyll has generally been used to distinguish 
only that substance which gives to plants their 
green hue, to use the word chromophyll as one 
expressive in a general way of vegetable colouring 
matters; for we erroneously refer to the colour 
green, many plants whose leaves are much more 
than green. There is, for instance, a tinge of blue 
in many a leaf, there is gold in the foliage of Limes, 
and gold in the leaves of the graceful Beech. 
