146 OKHAMANDAL MARINE ZOOLOGY REPORT 



change ; each mass plumped out and each of the wart-like papillae became the 

 base of a tiny arborescent tuft of branching threads. The general substance possessed 

 a certain amount of contractility when irritated, shrinking away when touched, 

 while the arborescent tufts suffered complete retraction at the place affected. The 

 tufts did not again expand fully for quite a minute after the cause of irritation 

 ceased. 



Examination under the microscope resolved each arborescent tuft into a group 

 of digitate papillae having perfectly colourless transparent walls, so tenuous as not 

 to be visible to the unaided eye. In each digitation was a branched or dendritic 

 tuft made up of brown cell-rows having a very close resemblance to the branching 

 threads of certain filamentous algse. It was the massing of these branched threads 

 that gave the arborescent appearance to each of the tufts referred to above 

 (Figs. 1 and 2). 



The cells of these branched strands were of uniform diameter, and each had 

 a well-defined nucleus. Besides forming the threads within the digitate papillae 

 these cells were also found in masses spread over the general surface of the organism 

 and forming brown patches here and there according to the relative abundance 

 of the cells. Other patches of brown, but deeper in tint and with a shade of red 

 in it, formed the remainder of the brown coloration of the surface, and wherever 

 such reddish-brown patches were, a great abundance of very minute red-brown 

 cells was indicated, the cells aggregated into rows (Fig. 8) or into irregular masses 

 (Fig. 9). Few or none of these minute brown bodies were met with in the digitate 

 papillae. 



The surface patches coloured grey were seen under the microscope to be composed 

 of granular cell-tissue, apparently colourless (Figs. 5 and 6). In each cell was 

 a clear spherical nucleus. The cells were irregular in outline, varying considerably, 

 but agreed usually in being elongated along one axis, so that they often formed 

 strand-like tracts. This grey tissue had a superficial resemblance to squamous or 

 tabular epithelium. It appeared to be restricted to the surface, but here and there 

 at some distance from the surface were small centres of a pale yellowish tissue made 

 up of cells, which, if not identical, appeared to be closely related ; indeed, the only 

 perceptible difference was that these more deeply seated cells were irregularly stellate 

 in outline (Fig. 7). 



The mass of the organism was distinctly areolar, large rounded cavities occupying 

 the greater part of the interior, separated more or less by a network of fine colourless 

 strands which appeared to be muscular. These colourless fibres were specially distinct 

 within the digitate papillae. On some of the threads protoplasmic centres could 

 be seen, each with a nucleus. A few gland-like bodies were observed in the digitate 

 papillae, containing secretion matter in the lumen. One was noticed to open by 

 a well-marked orifice upon the surface. Associated with the brown cellular strands, 



