Mr. Hogg's Observations on the Spongilla fluviatilis, 367 



Zooph.") thus mentions what he considered remarkable specimens : "Spongia 

 vulgaris fluviatilis in aquis stagnantibus ssep^ crassis crustis fundum obducit. 

 Talis crustse fragmenta parvulis Phryganearum larvis, membranaceis tubulis 

 in spongiosa substantia nidulantibus scatentis monstravisse mihi olim sum- 

 mum apud Goettingenses Botanicum celeberr. Biittnerum memini; nee simi- 

 les unquam invenire ipse potui." So one of my specimens will show how this 

 Sponge is seen occasionally to fix itself and to spread upon the tube or case of 

 a Caddis or Cadeworm, as related in the passage just cited. Another speci- 

 men here presented is interesting from its parasitical mode of growth, because 

 it has invested a moss {Hypnum riparium, Linn.) in a very beautiful manner. 

 In short, I may safely infer, from the many different substances to which I 

 have noticed the Spongilla fluviatilis attached, and from the many curious 

 places wherein I have observed its seedlike bodies growing, that wherever one 

 of these bodies can obtain a lodgement for itself, there it increases and flou- 

 rishes*, and consequently, that these bodies are in fact the true sporulesf or 

 ovules of the River Sponge, be it a vegetable or an animal production. 



Lastly, I beg to submit to your notice three specimens of the small fresh- 

 water Polypary, named Plumatella repens by De Lamarck, which I discovered, 

 for the first time I believe in England, in the month of August last among 

 some patches of the Spongilla from the same rivulet. 



* Two or three of these seedlike bodies having lodged in the mouths or openings of two fluviatile 

 shells that form part of the case of the caddis or larva Phryganea, now exhibited, clearly prove this : 

 they also show how the sponge begins to be developed. 



t Having yesterday received the new number (for July 1838) of the " Annales des Sciences Natu- 

 relles," seconde sdrie, torn. x. Zoologie, I have just perused the " Observations sur les Eponges et en 

 particulier sur la Spongille ou Eponge d'eau douce, par M. F. Dujardin." At page 9, this author, who 

 is convinced of the animality of Sponges, states, " Dans ces diverses parcelles vivantes, on voit des 

 ■ granules color^s en vert au printemps, grises ou jaundtres h, I'arrifere-saison, et que je ne puis regarder 

 comme des organes importans, ou comme des ovules de I'Eponge." But the experiments mentioned 

 in the preceding notes at page 366, will entirely refute the opinion of M. Dujardin, and prove without 

 a doubt that these are in reality the reproductive bodies of the Spongilla. On the other hand, 

 M. Dutrochet, in his very able " Observations sur la Spongille rameuse {Spongilla ratnosa, Lara., 

 Ephydatia lacustris, Lamour.," Spongia lacustris, Linn.), and in which he advocates the vegetability 

 of that species of Sponge, adds concerning its seed-hke bodies, " Ces corps sent done des espfeces 

 de tubercules, ce sont des reservoirs de matifere nutritive pour servir au ddveloppement du v^g^tal, 

 et k sa reproduction au printemps." See Annales des Sciences Naturelles, tom. xv. p. 212, 1828.^ 

 J. H., December 19, 1838. 



VOL. XVIII. 3 C 



