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



animal lodged within it. It would therefore be just as erroneous to decide 

 that this substance is of an animal nature merely from its smelling, on drying, 

 somewhat like carrion, as it would be to declai'e that the Phallus impudicus 

 among the Fungi, and the flowers of the Stapelia variegata amongst the Pha- 

 nerogamia, are both really animals, or, at all events, animal productions ; for 

 who, having once experienced the filthy odours given out from both these sin- 

 gular plants, did not instantly recognise their nauseous resemblances with the 

 most foetid and putrid animal matter? 



Likewise, some may perhaps be led to infer the animal nature of the Spon- 

 gillce from the numerous spicula, which constitute a not unimportant portion of 

 their composition, and considering that they are, if not identical, at least ex- 

 ceedingly analogous with those similar bodies, which are abundant in the 

 structures of some of the Polypiferous Alcyonia ; but these spicula do by no 

 means afford a sole indication of an animal substance, because many vegetable 

 productions are well known to secrete the like particles, which are termed 

 raphides* by modern botanists. 



Lastly, those naturalists who consider with Montaguf the likelihood of the 

 Freshwater Sponge being the nidus, matrix, or production of some unknown 

 insect or animal, and which surely might even at this day receive some 

 slightly additional weight from my discovery of the anomalous insect here al- 

 ready described:}:, I would beg to remind, that my successful experiments of hav- 

 ing raised, or grown, young Spongillce from their seedlike sporidia and locomo- 

 tive sporules, have in the most complete manner negatived such a supposition. 



Wherefore, my late researches on the Spongilla fluviatilis have at length 

 forced me to secede from my favourite and early opinion concerning its ani- 

 mal nature, and to adopt that of its vegetability : of the correctness of which, 

 the proofs (among others) derived, from the modes in which light acts upon it, 

 as well in bringing out the green colour, as in causing bubbles — most probably 

 oxygen — to be disengaged, when exposed to the full sunshine ; from its co- 

 louring matter remaining pale and unchanged when kept in the dark ; from 

 its sporules or reproductive bodies possessing the faculty of locomotion, like 



* These raphides are crystalline spicula, and consist most frequently of oxalate of lime. The spi- 

 cula of the Sponges are composed, either of carbonate of lime, or of silica. 



t See Wemerian Memoirs, vol. ii. part 1. p. 77, in note. See and, pp. 390, 391, 



