V COLOUR-PHENOMENA IN WORMS loi 



to form in alcohol a pure green solution without 

 fluorescence, and so to offer a marked contrast to 

 bonellin. It seems most probable that this pigment 

 is related to some of the derivatives of bonellin. 

 The same pigment appears to occur in smaller 

 amount in some other species of Thalassema and 

 in Hamingia. Both these genera are further stated 

 by Lankester to contain haemoglobin in the peri- 

 visceral fluid and muscles. 



In the Sipunculoidea, another order of Gephyreans, 

 integumental pigments appear to be absent, but in 

 Sipunculus and Phascolosoma the oxidised blood 

 contains a deep red pigment called by Krukenberg 

 haemerythrin. This resembles haemocyanin in being 

 colourless when reduced, and probably in having 

 a respiratory function. It belongs to a group of 

 pigments called by Krukenberg the Floridines, 

 characterised by their solubility in water and 

 glycerine, and their insolubility in the usual organic 

 solvents, such as alcohol, ether, chloroform, etc., as 

 well as by the readiness with which they undergo 

 oxidation. This pigment is similar to the one 

 already mentioned as occurring in the sponge 

 Hircinia ; it is, however, difficult to believe that it 

 can be respiratory there. 



The Colours of the Ch^topoda 



The colours of the Chsetopoda often display great 

 beauty, and may be structural or pigmental, or due to 

 a combination of the two. One of the simplest forms 

 of structural colour is that displayed by the earth- 

 worm, where the cuticle exhibits a faint iridescence 



