IV THE COLOURS AND PIGMENTS OF PROTOZOA 75 
contain phseodia or phaeodellae, 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 Coelomata, 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 
