NATURE OF EXORETORY PROCESSES IN MARINE POLYZOA. 135 
growing out into abnormally long and slender growing-points, 
in the funicular tissue of which carmine-particles derived from 
those originally taken up by the growing-points were present 
in the form of sharply circumscribed spherules, which con- 
tained (normal) yellowish granules in addition to the red 
pigment (fig. 22). 
c. Flustra papyrea. 
None of the tissues of this animal were shown to take up 
carminate of ammonia, the experiments with which, in the 
case of this species, were not altogether successful. 
C. Bismarck-Brown. 
A weak solution, sufficient to give the sea-water a yellow 
tinge, was found to give the best results. 
a. Bugula neritina. 
No part of the alimentary canal could be shown to take up 
Bismarck-brown ; but as the granules of the alimentary canal 
are normally very dark in this species it was not possible to 
be quite sure that none of the pigment had been absorbed by 
them. All the other structures which are naturally pig- 
mented, i.e. the funicular tissue, the pigmented part of 
the tentacles, the strongly pigmented region round each 
“aperture, and the pigmented parts of the growing-points, 
take up the Bismarck-brown freely. The fact that the ali- 
mentary canal in this species takes up neither indigo-carmine 
nor Bismarck-brown points to a physiological difference between 
it and that of allied species. It may be suggested at once that 
this difference is associated with the pigmentation of the funi- 
cular tissue. If it is assumed that the pigment-granules of 
the alimentary canal are in part of excretory nature—a ques- 
tion which will be further considered below—the difference 
between Bugula neritina and other species may be expressed 
by saying that some of the excretory functions normally pos- 
sessed by the alimentary canal are here performed by the 
funicular tissue, which is hence pigmented, 
