139 



a certain number of substances may enter a cell by diffusing 

 (eg. the vital stains), a large quantity of other substances may 

 not, and especially those, that might be food to the cell. This 

 entering or not-entering would in this case be a physical pheno- 

 menon, independent of the activity of the cell (lipoid-theory of 

 Overton). Although we are obliged, as Höber (30) 1911 points 

 out rightly, to admit beside this physical permeability still a 

 physiological permeability of the cells, in order to make the ab- 

 sorption of nutriment (in solution) conceivable, we may never 

 consider the absorption of vital stains by cells as a proof to the 

 >ility of also absorbing nutriment in solution. 



The capturing of solid food is generally stated for sponges. 

 As to this, the view of Vosmaer and Pekelharing (62) 1898 is 

 almost generally acknowledged in literature, as I mentioned already 

 in the Introduction. These investigators showed once more and 

 by better proofs than the others, that the flagellated chambers 

 would be the chief „eating-organs" of the sponge. 



These experiments were made in the following way: A Spon- 

 gilla or a Sycon, having been for some time in water with car- 

 mine or milk, was either immediately killed in 1 °l^ osmic acid 

 or placed back into pure water and killed afterwards. The sponges 

 were examined in sections or in maceration preparations. I will quote 

 here the description given by Vosmaer and Pekelharing: „In 

 sponges which had been for half an hour to two hours in water 



with carmine or milk we found a considerable quantity of 



carmine in the choanocytes, while in the pinacocytes and in the 

 cells of the parenchyma particles were seen here and there, but 



in a considerably smaller quantity than in the choanocytes 



If the sponge had remained for hours (to 24 hours) in the car- 

 mine, there was more carmine in the cells of the parenchyma 

 than in the choanocytes. If, after a stay of many hours in car- 

 mine, the sponge was placed back into pure water for some hours, 

 the carmine was abundantly found in the cells of the parenchyma, 

 and hardly at all in the choanocytes. Feeding with milk had 

 about the same results we believe we are entitled to 



