184 



The small (food-) particles are captured from the circulating 

 water within the flagellated chambers, viz. outside-between the 

 collars or between the bodies of the choanocytes, while thus, 

 so to say, the water is filtered clear (p. 142 — 146, Fig. 63, 65 — 

 68). Next these particles are taken up within the choanocytes, 

 united to conglomerates and ejected again into the „intercellular 

 plasmic ground-substance" (p. 146 — 148, Fig. 66, 69 — 71), from 

 whence the amoebocytes with symbiotic algae take them up in 

 their turn (p. 146—148, Fig. 71). 



The coarse (food-) particles are captured from the circulating 

 water outside and against the flagellated chambers at the side of 

 the incurrent canal, and such, because they remain sticking in or 

 against the prosopyles. The thin layer of apparently undifFerent- 

 iated flowing protoplasm, which covers that side of every flagel- 

 lated chamber with the exception of the prosopyles (p. 151 — 

 154, Fig. 72 — 74), then takes up each partiele and carries it off 

 aside into the tissue, so that the prosopyles again become access- 

 ible (p. 148—152, 155, Fig. 75). 



Finally the question was discussed, whether food can be cap- 

 tured by the sponge in still more ways (p. 155 — 156). 



22. No observations were made which could fortify the theory, that 

 sponges feed especially on organic substances in solution (p. 138). 



D. 



23. My principal results regarding the digestion of food have 

 already been mentioned in the discussion of the symbiotic relation 

 of sponge and alga (see point 17). I only added some new obser- 

 vations (p. 157 — 158). 



E. 



24. By observing the phenomena in my normally living mi- 

 croscopic preparations, I have come to the conclusion, that in 

 fresh-water sponges defecation — and very likely excretion 

 at the same time (p. 166) — -■ takes place on a large scale by 

 means of vacuoles, which occur along the walls of the excurrent 



