NATURE OF EXCRETORY PROCESSES IN MARINE POLYZOA. 137 
A remarkable form of cell, shown in Pl. III, fig. 20, was 
constantly noticed in this species, but in none of the others 
examined by me. Each cell consisted of a group of large 
vacuoles, some of which contained small granules or concre- 
tions, while others were completely filled with a number of 
minute granules, which always exhibited an active Brownian 
movement. 
The larger concretions in the former kind of vacuole are 
normally colourless, but in colonies treated with a mixture of 
Bismarck-brown and indigo-carmine most of them became a 
pale brown colour, while some of them had taken up a small 
quantity of indigo-carmine (fig. 20). 
These cells always occur in a special zone, in the growing- 
points, at the junction of the comparatively solid distal funi- 
cular tissue, and of the space in which the young tentacle 
sheath lies. They are perhaps in some way concerned in the 
excavation of this space out of the more solid funicular tissue 
of the younger part of the zoecium. They are also found, 
here and there, in the cavities of the older zowcia. 
They have been noticed in the same species by Claparéde,! 
who describes them as finely granular, brown structures, oc- 
curring only in the cavities of the buds, and only found in 
this particular species. 
c. Flustra papyrea. 
The granular parts of the stomach and cecum become in- 
tensely coloured by the Bismarck brown, which also appears 
in smaller quantities in the rectum. The intestine, the inner 
borders of the pharyngeal cells, and the tentacles may become 
diffusely coloured. Small quantities of the pigment may 
appear, in spherules, in cells belonging to the funicular tissue 
(never in cells of the type shown in fig. 14). 
D. CARMINE PARTICLES IN SUSPENSION IN SEA-WATER. 
The carmine particles are readily swallowed by the polypides, 
whose alimentary canals become filled with dense masses of 
1 ‘Zeits. f. wiss. Zool.,’ xxi, pp. 141-2, pl. viii, fig. 1. 
