Mr. Hogg's Observations on the Spongilla fluviatilis, 365 



frequent in such Sponge must be their eggs." — " Der Schwamm des siissen 

 wassers soil eine absonderung ihrer kohren oder zellen sein, ist sehr wahrschein- 

 lich. Die korner, welche man so haufig in solchen schwainmen findet, sollen 

 die eier sein." 



Lamouroux, at page 3 of his "Hist, des Polyp. Corall. Flex." 1816, says, 



"_Linn6 dit qu'en automne on voit des semences dans I'Eponge fluviatile. 



Kalm semble avoir copi6 le naturaliste Su^dois. Ces auteurs prenaient pour 

 des fructifications, des Cristatelles dess^chees, ou des grains opaques d'une 

 substance encore inconnue, dont les Eponges d'eau douce se trouvent quelque- 

 fois enti^rement remplies." 



Also, De Lamarck inquires, " Les petits grains observes dans les Spongilles 

 seraient-ils des gemmes propres k produire les Cristatelles, comme I'observa- 

 tion de Lichtenstein* semble I'indiquer ?" (p. 99. torn. ii. of " Hist. Nat. des 

 Anim. sans Vert./' edit. 1816.) 



Hence, from these last three passages, we find that Lamouroux held these 

 seedlike grains not to pertain to the Spongilla, but that they were dried or 

 withered Cristatella;, or else certain opake grains belonging to some unknown 

 substance : and MM. Oken and De Lamarck inclined to consider them as 

 the eggs or reproductive germs or gemmules of the Cristatella vagans (De 

 Lamarck). This small polypary in its different stages, and several of its po- 

 lypes, are well represented in Roesel's " Insecten," vol. iii. tab. 91. p. 559. 



Now I cannot for a moment suppose that these seedlike bodies are the 

 germs or ovules of the Cristatellce, partly for this reason ; because I have not 

 yet succeeded in discovering any of those minute Zoophytes in the same rivulet 

 which the Spongilla inhabits ; and as I have found the same bodies to be 

 abundant in different specimens of the Spongilla fluviatilis, not only in the 

 summer and autumn, but also in the spring : it is extremely remarkable, and 

 indeed most improbable, that I should not have been able to notice the Cris- 

 tatellce in different stages of their development in that water, if these bodies 

 were in reality their ovules or germs ; whilst, on the contrary, I have con- 



* There is an article by H. Lichtenstein on Sponges {Suesvampene) in " Skrivter af Naturhistorie," 

 4 Bind, 1 Hefte, Kiobenhavn, 1,797, where he, at page 115 and the folio wing page, speaks of the 

 river Sponge (Flod-suesvamp) : but, being written in Danish, I have not been able to read it, though 

 I presume the author is the same Lichtenstein mentioned by De Lamarck. 



