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 

 Chmtopterus, of the " liver " of MoUusca 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 chsetopterin 

 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 



