CHAPTER IV 



THE COLOURS OF PROTOZOA, SPONGES, AND 

 CCELENTERA 



Pigments of the Protozoa, their Characters, Variations, and 

 probable Origin — Coloration of Sponges and Coelentera 

 — Distribution of Colours — The Colours of Corals and 

 Sea-Anemones — Colour-resemblances in the Coelentera 

 — The Effect of Light upon the Development of Pigment 

 — The Pigments of the Coelentera — Optical Colours. 



The pigments of the PrcJtozoa are mostly very plant- 

 like, chlorophyll and lipochromes being exceedingly 

 common. There is often an interesting alternation 

 between chlorophyll and red or yellow lipochrome 

 pigments, very similar to that seen in the vegetative 

 organs of the higher plants. Thus Hcematococcus 

 is sometimes red and sometimes green : it is always 

 red in the resting stage, and gradually acquires the 

 power of movement and a green colour simultaneously. 

 Sometimes in this form and in Euglena there is 

 merely a red ring round the nucleus ; when the 

 green colour develops it begins at the periphery 

 and gradually spreads inwards. Rostafinski found 

 that the red colour is produced by a combination of 

 two lipochromes, distinguished by their solubilities, 



