i66 
COLOUR IN NATURE 
CHAP. 
“ of a modest, almost unadorned green colour ” 
( Insects , p. 302). 
It is impossible to speak of the colours of the 
Orthoptera without mentioning the remarkable leaf- 
insects ( Phyllium ). As is well known these insects 
exhibit an extraordinary resemblance to leaves both 
as to structure and colour. They are, however, when 
hatched not green but red ; after a few days, during 
which they feed greedily on leaves, the colour be¬ 
comes yellow, and after the first moult it is greenish. 
After this the green becomes more and more intense 
after every moult (Becquerel et Brongniart), but it is 
asserted that when dying the colour changes, exhibit¬ 
ing the hues of a fading leaf. In dried insects the 
colour is very fugitive. All these characters suggest 
an origin from the pigment of the food, and MM. 
Becquerel and Brongniart have sought to prove this 
spectroscopically. They found that the pigment 
occurs in amorphous granules in the subcutaneous 
connective tissues, and that it gives a spectrum 
closely resembling that of the green leaves upon which 
the insects feed. As, however, the whole insect was 
employed for spectroscopic purposes, without appar¬ 
ently any effort being made to remove the gut or its 
contents, the observations are not very conclusive. 
The frequency in the order of green colours associated 
with herbivorous habit may suggest that derived pig¬ 
ments are common and important in coloration, but, 
on the other hand, we have cases like that of the 
species of Mantis where a green colour is not infre¬ 
quent, and yet all are purely carnivorous. There 
seems also nothing intrinsically improbable in the 
idea that the green colour may be produced by a yellow 
