CHAPTER V 



COLOUR-PHENOMENA IN WORMS 



Colours of Turbellaria and Nemertea — Pigments of Gephyrea — 

 Colours of the Chaetopoda, Structural and Pigmental 

 Colours — The Pigments of the Capitellidse — General 

 Characters of Coloration of Leeches and Origin of Mark- 

 ings — Pigments of Polyzoa and the Origin of Pigmentation. 



As central and unspecialised forms, the worms are 

 of considerable interest in a comparative study of 

 colour, and there are several interesting facts in 

 regard to them which make it desirable that we 

 should consider the more important groups suc- 

 cessively. 



The somewhat grim associations which cluster 

 about the Platyhelminths do not lead us to expect 

 bright colours among them, and yet in point of fact 

 the free living forms often exhibit great brilliancy. 



Among the Turbellaria pigment frequently occurs 

 in the cells of the epidermis, in the interstices between 

 these cells, or in the parenchyma of the body. 

 Many, such as Convoluta, contain in the cells of this 

 parenchyma the so-called symbiotic Algae of green 

 or brown colour. These chlorophyll cells have no 

 cellulose envelope, and often contain pyrenoids. 



