146 



7 — 8 /o« on an average. The right one, on the contrary, was more 

 normal viz. narrower, with the ordinary width of 3 — 4 jw, and 

 constant as to size. Further, I think to have observed once a 

 great change of a prosopyle of another chamber, viz. that it 

 narrowed from an at first long, rather wide fissure to an opening 

 of 4 f/,. Taken for itself this seems a queer observation, rather to 

 be explained by optical delusion. But it deserves our attention, 

 when one considers it in connection with the preceding and with 

 what Delage (15) says about the prosopyles of Ephydatia: „meats 

 intercellulaires de grandeur et de forme extremement variables, 

 produits par ecartement peut-être temporaire des cellules flagel- 

 lées pour donner acces a I'eau", while also Weltner (65) writes 

 that they can arise and disappear again. In fact, this would be 

 logical; as in that way a flagellated chamber, after the choano- 

 cytes near the existing prosopyles had been overloaded with par- 

 ticles from the water, could open quite new prosopyles simply 

 by separating some other choanocytes. 



Finally I want to remind, that all these experiments with the 

 normally living microscopic preparations could only be made with 

 tissue of Spongilla (as Ephydatia grows so very slowly). 



I now must answer the 3''^ question, namely ivhat ha])pens to 

 the particles from the ivater, after they have heen captured by the 

 choanocytes at the base of the collars. 



Those particles — carmine grains or symbiotic algae — are 

 then taken up by the protoplasm of the choanocytes and carried 

 along into the cell (Fig. 66). How, I have never been able to 

 observe; but one sees them enter the choanocytic layer; while 

 one also sees them very distinctly, either in intact flagellated 

 chambers or in isolated choanocytes, within the separate cells 

 and always free in the protoplasm, never enclosed in a vacuole. 



Next those particles are rather soon ejected by the collar cells 

 again into the surrounding tissue — let me say here, into the 

 „intercellular plasmic groundsuhstance'\ in which also the chloro- 

 phyll carrying amoebocytes are to be found (chap. F.) — from 

 whence those amoebocytes take them later on. This fully corresponds 



