158 SIDNEY F. HARMER. 
they had taken up, and fresh granules had to be developed 
later. 
Similarly the alimentary canal of B. avicularia was able 
to rid itself of Bismarck-brown, a process involving the loss of 
its normal granules, by excreting it into the lumen of the ali- 
mentary canal, enclosed in spherules noticed as of normal 
occurrence in this species; these spherules are probably con- 
cerned in the excretion of some of the normal pigments of the 
alimentary canal, although their function may be in part a 
digestive one. 
Again, the pigments taken up by the alimentary canal, 
whether carmine, indigo-carmine, or Bismarck-brown, passed 
for the most part into the “ brown bodies” at the time of the 
degeneration of the polypides. In F. papyrea it was definitely 
proved that indigo-carmine contained in the “ brown bodies” 
left the zocecia by way of the alimentary canals of the new 
polypides. In the two species of Bugula the “ brown bodies,” 
coloured by pigments taken up at an earlier period, were left 
behind in the zoecia. 
The leucocytes charged with indigo-carmine did not appear 
to take any further active part in the life of the zocecium; but 
they certainly play the important part of retaining the greater 
quantity of the pigment which originally soaked into the 
tissues. The other tissues thus remain without the slightest 
trace of a blue coloration ; and it can hardly fail to be admitted 
that the leucocytes are performing an excretory function, so 
far as they are exercising a selective absorption of an abnormal 
substance like indigo-carmine from the other tissues. In dead 
zocecia all the tissues become at once diffusely stained with 
indigo-carmine. So long as the zocecium remains alive the 
leucocytes retain this pigment, and shield other tissues from 
its action. 
On the regeneration of a polypide the growing tissues are 
invariably quite free from the artificially introduced pigments, 
The exposure to the action of these bodies may in some cases 
result in the degeneration of the polypide or of the funicular 
tissue ; but the young polypide-bud and its muscles, as well as 
