174 



quite independent of the former. I too foimd in living tissue the 

 amoebocytes with symbiotic algae and the cells with equally 

 large grains imbedded in an apparently imdifferentiated inter- 

 cellular plasmic ground-substance (p. 17, 146 — 148, 156, 168, 

 Fig. 69, 71), in which numbers of enclosiires (eg. oildroplets 

 and sometimes symbiotic algae) and also vacuoles (p. 163 — 165), 

 and which, at the side of the canals, was one time lined by 

 cells (eg. pinacocytes) and not so another time (p. 154). "When 

 rubbed to pieces as well as when warmed, or af ter killing and 

 macerating, the whole tissue^ so also that undifferentiated plasmic 

 subsfmice, proved to ronsist of amoehoid cells with nucleus (see 

 also p. 153—154, 169—170). 



As to the observation, that that plasmic substance (i. e. the 

 ground-substance of the parenchyma) was not entirely lined with 

 pinacocytes, I mentioned already on p. 154 that the possibility is 

 not excluded that pinacocytes were present in fact, but not to 

 be discovered by their line extension. With regard to the above 

 described phenomena of ingestion of food in the flowing plasmic 

 layer outside and against the flagellated chamber (p. 152) and 

 of defecation by vacuoles in the excurrent canal walls (p. 163 — 

 166), it seems more likely that, at least there where those pro- 

 cesses take place, the pinacocytic covering of the canals will be 

 missing. Por that would certainly advance the rapidity. On the 

 other hand my observation made during the capturing of coarse 

 food particles outside and against the flagellated chamber, viz. 

 that first the partiele remains quiet for about 10 minutes before 

 being carried off by the flowing plasmic layer (p. 152), might 

 possibly show that thin pinacocytes, which then must first be 

 passed by the food partiele, are present. 



As we have now seen that all apparently undifferentiated plas- 

 mic ground-substance consists of amoeboid cells, we may conclude 

 that the layer of flowing plasm at the outside of the flagellated 

 chambers (p. 152, 156) is also formed by such cells. And we 

 may also conclude that the (food-) transport (from the choanocytes 

 to the amoebocytes with symbiotic algae, for instance) which, as 

 we saw above (p. 146 — 148, 168), takes place through the so 



