92 COLOUR IN NATURE chap. 



at least can be made to yield very bright green 

 derivatives. 



Dr. M'Munn (1885) has described by means of 

 the spectroscope a number of other pigments in sea- 

 anemones, but too little is known of these to make it 

 profitable to detail here their names and properties. 

 There is, however, one interesting pigment, called by 

 Moseley polyperythrin, which deserves further notice. 

 Moseley found this pigment in a number of simple 

 stony corals and in a few anemones and jelly-fish, 

 almost all from deep water. It is of a deep madder- 

 brown colour, and in the case of the corals sometimes 

 coloured uniformly both the soft parts and the coral, 

 sometimes the soft parts only. Further, in some 

 specimens it was uniformly distributed, while in 

 others it occurred in streaks or was totally absent. 

 The pigment dissolves in acidulated alcohol or in 

 dilute acid to form a pink solution with green 

 fluorescence, and gives a spectrum which in some 

 respects resembles that of the pigments of the 

 chaetopterin group. It seems not improbable that 

 this pigment is the result of the modification of a 

 pigment allied to the " chlorophyll " of Anthea. 



Another interesting series of pigments, apparently 

 not allied to the preceding, are those producing the 

 blues and browns of the surface jelly-fish. There is 

 reason to believe that the blue colour of Cyanea, of 

 the common Aurelia, of Rhizostoma, and of Vellela 

 are all due to a pigment called by Krukenberg 

 Cyanein, which is recognised by the following 

 characters. It is soluble in water, especially in 

 water containing neutral salts {e.g. sea-water). It is 

 unaltered by weak acids, but strong acid, alcohol, 



