CELLULAR DEFENERATION AND FORMATION OF PIGMENT. ] 09 



(1) Lytocarpns filamentosus (Lam.). 

 PI. XII, figs. 1-3; text-figs. 1-3. 



Ill this species hotli dark brown or black specimens and 

 pale liorn-colonred colonies occur. The pigmented specimens 

 were found in bare exposed pools at Alexandra Junction, 

 Natal, and at Sisters' Rock, Port St. John, Pondoland. The 

 colonies were 4-5 in. in length and were clearly of consider- 

 able age. The non pigmented specimens were found at Park 

 Rynie, Natal, in sheltered pools considerably overgrown with 

 weed ; they were small, young colonies, not more than about 

 1^ in. in height. 



The pigmented colonies were not in a vigorous condition ; 

 a good many of the polyps appeared to be moribund, and 

 some portions of the colonies were completely dead. A micro- 

 scopic examination showed that the blackness arose through 

 the fact that large numbers of both the ectoderm and endo- 

 derm cells were densely crowded with relatively large, dark 

 brown granules (PI. XII, figs. 1-3). 



In text-fig. 1, A, a fairly vigorous polyp and a piece of the 

 cojnosarc are illustrated in longitudinal section. Pigmented 

 areas of considerable size are seen in the endoderiii, in the 

 general ectoderm, and in the thin, outer sheets of ectoderm. 

 Mostly these areas correspond to separate cells which assume 

 an oval shape, but sometimes there is formed a reticulum of 

 pigmented strands consisting of several cells or portions of 

 cells. In fig. B are seen two endoderm cells and an ectoderm 

 cell in process of transformation. Figs. c-Q illustrate the 

 stages of transformation of an ectoderm cell in the outer 

 ectoderm sheets ^ seen in fig. a. 



Usually the pigment granules appear in little clusters in 



' It may be mentioned here incidentally that these thin, outer ecto- 

 derm sheets would appear to functionate as structures by means of 

 which the ccenosai'c and polyps may cling to the inner surface of the 

 perisarc-tube and hydi-othecse. In the case of operculate species of 

 Sertularia these sheets around the polyp are supposed to serve as 

 opercular muscles. 



