IV THE COLOURS AND PIGMENTS OF PROTOZOA 75 



contain phseodia or phaeodellas, which are similar 

 masses impregnated with fine granules of brown 

 pigment of unknown characters. Several sug- 

 gestions as to function have been made, but none 

 seems well established. Karawaiew considers that 

 they play an important part in the assimilation of 

 food, but in what respect is not quite apparent. 



Among the Foraminifera, pigments perhaps of 

 lipochrome nature are very common. We have 

 already spoken of Globigerina as being bright red 

 in mass ; a similar pigment is described in some 

 detail by Fritz Schaudinn in Myxotheca arenilega. 

 This is a very large form, and in it the whole of the 

 protoplasm is coloured a bright Pompeian red by 

 means of a finely granular pigment. The pigment 

 is soluble in alcohol, and was found to be absent 

 in only two cases out of a large number examined. 

 The organism was observed to feed on Copepoda, 

 which are often very brightly coloured organisms, 

 and we must allow the possibility that the pigment 

 was derived from the food. It may be thought that 

 this suggestion is too freely made for the colours of 

 the Protozoa, but it should be remembered that in 

 organisms of such great simplicity it is difficult to 

 clearly distinguish between pigment directly intro- 

 duced with the food and intrinsic pigment ; in their 

 case derived pigment has not quite the same mean- 

 ing as in the case of coelomate animals. Even in 

 the Ccelomata, indeed, colouring-matter introduced 

 into the gut with food may have a direct importance 

 in coloration ; many of the transparent herbivorous 

 worms such as Nemerteans or Annelids are coloured 

 green by the contents of the gut. It is likely that 



