NATURE OF EXCRETORY PROCESSES IN MARINE POLYZOA. 167 
Fic. 19.—B. neritina. Indigo-carmine. 64th hour. Three leucocytes 
(Zeiss, F). 
Fies. 20—22.—B. avicularia. 
Fig. 20. Bismarck-brown and indigo-carmine (mixed). 40th hour. 
Three leucocytes containing indigo-carmine, and two of the cells 
which contain minute granules exhibiting a Brownian movement, or 
larger concretions. These cells appear to have taken up minute 
quantities of Bismarck-brown and of indigo-carmine (Zeiss, F). 
Fig. 21. (Same treatment as Fig. 20.) Two leucocytes and one of the 
cells with colourless granules found in the body-cavity of this species 
(Zeiss, F). 
Fig. 22. Carminate of ammonia. 330th hour. Two leucocytes, whose 
natural colour is unaltered, and several of the well-defined spherules, 
found especially near the growing-points, and containing carmine as 
well as natural brown pigments (Zeiss, F). 
Figs. 23 and 24.—F. carbasea. 
Fig. 28. A complex of leucocytes which have taken up indigo-carmine, 
and which contain granules of deposited indigo-carmine as well as 
natural pigments (Zeiss, F). 
Fig. 24, An individual leucocyte (Zeiss, F). 
