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ture about these processes. In the first place one has of course 

 always thought probable the excretion of dissolved matter by 

 diffusion (see Burian (10) 1910) all over the inner or outer sur- 

 face of the sponge, though in fact no one has ever mentioned 

 any strong proof for it. On the other hand Haeckel (25) 1872, 

 Lendenfeld (36) 1883, Weltner (65) 1891 and Delage and 

 HÉROUARD (16) 1899 supposed defecation and (or) excretion as 

 being performed by the choanocytes; while Minchin (45) 1900 

 ascribes this function for a considerable part to the amoebocytes. 

 Bidder (5) 1892, on the contrary, to the porocytes, and Loisel 

 (41) 1898 thinks the excretion being performed by the contraction 

 of the mesogloea (ground-substance). 



None of these investigators, however, mentions a definite ob- 

 servation of the phenomena. On the contary the following do: 



Masterman (42) 1894 found, if a sponge (Grantia compressa), 

 after having been fpr some minutes in a carmine suspension 

 and afterwards in pure water, had been killed with osmic acid, 

 that amoeboid cells filled with carmine protruded from the ex- 

 ternal surface, as if they were just going to be ejected. While 

 something the like seemed to have happened also at the internal 

 surface, as there were cells, ejected and laden with carmine, to 

 be found inside the canals too. Masterman says: „We have 

 here an example of a process of intracellular excretion for the 

 removal of waste solids". 



• Also the opinion of Cotte (13) 1904 is partly founded on 

 observation; as far as I know it is the last extensive publication 

 about excretion in sponges. As summary he gives: „Les cellules 

 mésogléiques (amibocytes, spongoblastes, etc.) rejettent leurs pro- 

 duits de désassimilation, sous forme de spherules, dans la sub- 

 stance interstitielle qui les expulse graduellemement. Les sphe- 

 rules usees des cellules sphéruleuses clasmatosées sent expulsées 

 par la substance fondamentale ; un certain nombre de sphéru- 

 leuses vont s'éliminer d'elles-mêmes an niveau des canaux. Les 

 choanocytes excrètent directement dans les chambres". This about 

 the excretion, about defecation: „Après I'ingestion de produits 

 inertes les chaonocytes rejettent dans les chambres une grande 



