122 BENE ST WARREN. 



and later they appear to fuse together partially or completely 

 to form a compact ball (fig. m) . It is not always clear that 

 the spherical bodies invariably correspond to a single cell, 

 sometimes they appear to consist of a modified portion of the 

 cytoplasm of a single cell, which rounds itself off and is con-' 

 verted into a spherical mass embedded in the general proto- ' 

 plasm of the living cell (fig. n). 



The bodies measure about 8 /i in the long axis and are 

 mostly of a somewhat elongated oval in shape. They do not 

 ■differ greatly in shape or size, whether they are in the ecto- 

 derm (fig. o) or endoderm (fig. p). A superficial examination 

 might readily enough lead to the supposition that the struc- 

 tures are parasitic protozoa or symbiotic algte with yellow 

 chlorophyll corpuscles ; but the greenish colouring matter 

 appears to be quite insoluble in alcohol, aiid eveiy stage can 

 be traced in the transformation of a tissue cell into these 

 yellow bodies. For these reasons the yellow bodies are 

 regarded as similar in general character to the black pigment 

 areas of the species previously described. 



(5) Sertularia linealis Warren. 



Text-fig. 8. 



In the few available specimens of this species there 

 occurred but little pigment-degeneration, but in one specimen 

 a certain amount was found in the ectoderm (text-fig. 8). 

 The degeneration was of the type of a vacuolated protoplasm 

 with the walls lined by a deposit of black pigment. In this 

 specimen practically no degeneration was found in the endo- 

 derm. The degeneration areas would seem to comprise a 

 group of interstitial cells. 



(6) Sertularia loculosa Bole. 

 Text-fig. 9. 



The type of pigment-degeneration is very distinctive in 

 this species. In the black specimens pear-shaped, dark 

 brown bodies are found both in the ectoderm and endoderm 



