128 ERNEST WARREN. 



action oil them. The granules or masses vary considerably 

 in the intensity of coloration, and a study of numerous 

 sections leads to the view that the first products of degenera- 

 tion of the living pi'otoplasm consist of pale or nearly colourless 

 granules of a proteid nature and of a mucilaginous, some- 

 what refringent, clear substance in which the granules lie 

 embedded like cocci in a zooglea-matrix. Gradually the 

 granules become coloured dark brown or black by a further 

 •decomposition, and a general coloration of the colony results 

 therefrom. The protoplasm involved in the degeneration 

 processes is gradually transformed into these products, and 

 if the whole of the cell is thus transformed the cell dies. 

 The nucleus sometimes swells, as described in the case of 

 ganglion cells of an animal killed by sunstroke, and the 

 chromatin is dissolved. Usually the conspicuous nucleolus 

 persists unaltered after the chromatin has disappeared, but 

 ultimately even this can be no longer found. 



In Lytocarpus filamentosus (text-figs. 1-3), the cells of 

 both the ectoderm and endoderm are similarly affected. The 

 individual cells become converted into oval masses of dark 

 brown granules or globules. The average size of the masses 

 is about 25/z x 9/x, and the diameter of the largest granules is 

 about 0'7 ju. The death of the colony, or portion of a colony, 

 does not occur until a very large number of the cells become 

 involved. Contiguous cells may be affected, and a coarse 

 reticulum of degenerated tissu.e maybe formed in the ectoderm 

 and endoderm. 



In Thuiaria tubuliformis (text-figs. 4 and 5) pigment- 

 degeneration occurs in both the ectoderm and the endoderm. 

 In the case of the endoderm, a cluster of cells becomes 

 affected, and an oval, chambered structure with pigmented 

 walls arises. A frequent size is about 45 ^ x 30 ju. Some- 

 times the structure is greatly elongated (e.g. 0*2 mm.) in 

 the long axis of the coenosarc-tube. The ectoderm cells may 

 become swollen and erupted by the formation of cavities ; 

 but typically there is no very conspicuous swelling or coarse 

 vacuolation of the protoplasm in the ectoderm. In the 



