438 THE DIGESTION OF SPONGES. 



The intracellular digestion, discovered by Lieberkiihn (1) and 

 Metschinkoff (2) is probably effected by the amcehoid wandering 

 cells, whilst only the epithelial cells have the function of trans- 

 mitting the nourishing material to them. 



Lieberkuhn's, Metschinkoff's and my own experiments were 

 made with Carmine and not with neaaly nourishing material, so 

 that these conclusions are open to a little doubt as Metschinkoff 

 (3) remarks. His statements based on a series of most interesting 

 experiments, however, make it probable that in the Sponges the 

 nourishment is treated similarly to the Carmine granules. 



The question whether the Sponges digest with the Ectoderm or 

 with the Entoderm cannot yet be decided. But it does not appear 

 improbable that both layers (Polejaeff I.e.) may have that function. 

 The Keimblatter of other Ccelenterata are nearly analogous, so 

 that we can conclude that the layers of the much less highly 

 organised Sponges are still more so, and that we have in the 

 Sponges indifferent germinal layers before us. 



(1.) Lieberkiihn. Beitrag zur Entwickelunesgeschichte der Spongillen. 

 Miiller's Archiv. Band 1836, Seite 385 ff. 



(2.) E. Metschinkoff. Spongiologische Studien, Zeitschrift fur wis. Zool. 

 Band XXXII., Seite 371-374. 



(3.) E. Metschinkoff. Ueber die Introcelluljire Verdauung bei wirbellosen 

 Thieren. Arbheiten aus den Zool. Inst. d. Universitiit Wien, Band V., 

 Seite 25, 26 u.o. O. 



