NATURE OF EXCRETORY PROCESSES IN MARINE POLYZOA. 149 
remains of the old polypide. The cecum of the young poly- 
pide soon projects beyond the proximal side of the ‘‘ brown 
body,” which is ultimately left near the distal end of the 
zocecium, and at its posterior side (fig. 17). 
Nearer the base of the colony the zoccia usually contain at 
least two ‘‘ brown bodies,’”’! sometimes three, which always lie 
at the back of the zocecium, and which have probably been 
formed by the disintegration of as many successive polypides. 
The older zocwcia also contain numerous brown spherules, 
which have resulted from the disintegration within the zocecium 
either of the older “ brown bodies” or of the pigmented 
funicular tissue.? The leucocytes, in normal old zocecia, retain 
their ordinary, slightly yellowish, clear colour, and the zocecium 
further contains a certain quantity of ordinary funicular 
tissue. 
No change of importance was noticed in the blue-coloured 
leucocytes at any period of the experiments in either of these 
species of Bugula. To the end of the observations they 
retained their bright blue colour, and were scattered in the 
meshes of the funicular tissue. In some cases they became 
more or less aggregated into masses situated near the ‘‘ brown 
body” (see fig. 17). In other cases some of the pigment 
appeared to pass from the leucocytes into the ‘ brown body,” 
apparently by immigration of the entire leucocyte into the 
latter ; but it was not quite certain that this was a normal 
process. 
The effect of immersion in indigo-carmine on B. neritina 
was, in some cases, to induce the degeneration of most of the 
polypides. This was noticed, for instance, in one set of 
colonies at the beginning of the fourth day (seventy-three 
hours) after the first treatment with indigo-carmine solution. 
New polypide buds were being formed in most of the zocwcia 
at the fifth day (114 hours), and tentacles had appeared at the 
seventh day (148 hours). 
1} «Brit. Marine Polyzoa,’ vol. i, 1880, p. 53. 
* Claparéde, ‘Zeits. f. wiss. Zool.,’ xxi, p. 154; pl. ix, fig. 1C; pl. x, 
fig. 2. 
