90 
COLOUR IN NATURE 
CHAP. 
These observations taken together seem to show that 
the pigment belongs to an interesting group of 
colouring - matters, which, as already mentioned, 
includes the pigments of the worms Bonellia and 
Chcetopterus , of the “ liver ” of Mollusca and of some 
other animals, all of which present some superficial 
resemblances to chlorophyll. In view of the fact 
that the cells of the “ liver ” in Mollusca contain 
yellow-brown granules which certainly contain the 
characteristic pigment (often called enterochloro- 
phyll), I am of opinion that it will probably be 
found that the so-called yellow cells of Anthea are 
merely granules of the characteristic pigment, prob¬ 
ably mingled with some other. Dr. M £ Munn (1885) 
on spectroscopic grounds certainly denies that the 
Anthea pigment corresponds to his “ enterochloro- 
phyll,” but as the animals contain a mixture of 
pigments, it seems not improbable that the anomalous 
appearances noticed by him were due to the simul¬ 
taneous occurrence of several pigments in the same 
solution. The resemblances to the chaetopterin 
group are certainly very striking. Now these 
“ yellow cells ” are widely distributed among sea- 
anemones, and if we may assume a similar wide 
distribution of a pigment of the chaetopterin group, 
it is possible to account for some of the remarkable 
colour-phenomena of the Ccelentera ; these may be 
merely the result of the properties of the dominant 
pigment. 
The better known pigments of the chaetopterin 
group, viz. chaetopterin, bonellin, and “ entero- 
chlorophyll,” show two marked peculiarities. In the 
first place, associated apparently with their complex 
