Reproductive Processes of Sponges. 377 



gilla with carmine the particles entering by the pores were 

 conveyed to and stuck in (" stecken ) the ampullaceous 

 sacs (" Wimperorgane ") (no. 7, p. 384) ; also that Infu- 

 soria passing through the " canal-system " were taken into 

 the parenchyma (" Korperparenchym "), and there falling 

 to pieces, after some time disappeared without leaving a 

 trace behind, after the manner of an infusorium which had 

 been devoured by an Actinophrys (ib. p. 388). 



Although nothing is said here, again, about " nourish- 

 ment," no one can doubt what was passing in Lieberkuhn's 

 sagacious mind at the time, viz. that the Infusoria thus 

 afforded nutrient matter to the Spongilla. 



We now come to Hackel's views in 1872, viz. that the flagel- 

 late cells of the endoderm (" Geisselzellen des Endoderms") 

 are exclusively the organs of reception for the digestion of the 

 food (no. 11, vol. i. p. 372) ; and these we may pass by with 

 Metschnikoff's observation, viz. that they are theoretical and 

 not founded on matter of fact (no. 20, p. 372). This brings 

 us to the following statements of Metschnikoff himself in 

 1879, made under the heading " Ueber die Nahrungsaufnahme 

 bei Spongien" (no. 20, p. 371). 



Beginning with Lieberkuhn's observations, Metschnikoff 

 observes that they were made more than twenty years ago, 

 and that their result has of late been " lost sight of." If it 

 had not been for Lieberkuhn's observations, my own, which 

 were made seven years previously, would have shared the 

 same fate (no. 5, p. 400). 



With Metschnikoff undue prominence seems to be given 

 to the cells of the parenchyma (mesoderm) in the nourish- 

 ment of the sponge. It is true that he says the ampullaceous 

 sacs (" W^imperkorbe ") were " usually " empty, and that in 

 some sponges nourishment is carried on by the mesodermal 

 element. But why, with the facts above stated, should he 

 give illustrations (no. 20, Taf. xxii. figs. 16, 17) wherein the 

 mesodermal cells are represented as charged with particles of 

 carmine and the ampullaceous sacs (" Wimperkorbe ") empty, 

 without in the text alluding to the opposite results of other 

 experimenters, and conclude his observations with the state- 

 ment that it was clear that the mesodermal cells could take 

 in the material and were more or less able to digest it (no. 20, 

 p. 374) ? — which implies that they alone are the nutrient 

 organs, as the ampullaceous sac (" Wimperkorb") is not men- 

 tioned. 



It is possible, and I should think probable, that Metsch- 

 nikoff has never seen my paper " On the Ultimate Structure 

 of Spongilla" (no. 6), and therefore is not aware of the 



Ann. & Mag. N. Hist. Ser. 5. Vol. iv. 27 



