38 Linnean Society ^ [June 4, 



He next showed that no arguments in support of the fancied ani- 

 mality of the Spongilla can be brought forward, either from its smell- 

 ing like carrion or animal matter, or from numerous spiculae being 

 present in its composition. And the manner in which he raised 

 young Spongilla from the seed-like sporidia and locomotive sporules 

 makes it perfectly conclusive that this freshwater sponge cannot be, 

 as Montagu supposed, the nidus of some aquatic insect, although 

 such an opinion might, without those successful experiments, have 

 been somewhat confirmed by the author's discovery of an unknown 

 and anomalous insect, which he has at present only observed inhabit- 

 ing this production. Some specimens of this small insect were ex- 

 hibited, and presented to the Society. 



Mr. Hogg concluded his letter with some general remarks on the 

 nature of the Spongia marina. He stated that hitherto he had al- 

 ways accounted these substances as being principally composed of 

 an animate or live jelly, which was endowed, as some authors af- 

 firmed, with a certain degree of sensation, and consequently had, 

 fourteen years ago, instituted for them an order " Gelatinifera," 

 which he arranged the last among the Polyparia Composita. That 

 on becoming convinced by his late researches on the river sponge of 

 its vegetability, he began in some measure to concur in the opinion 

 of Montagu, that that substance might probably be quite distinct 

 from the sea sponge, and to think that the latter might still be of an 

 animal nature ; but, on a more recent examination and comparison 

 of the Spongilla with many of the Spongia, he has found that there 

 exist no real grounds for that opinion, and that there scarcely is even 

 a generic difference between them. 



The author then compared the freshwater sponge with the sea 

 sponge, and showed, among other extreme resemblances in their 

 structure and composition, that many of the latter possess similar 

 seed-like bodies or sporidia, as well as the locomotive germ-like bo- 

 dies or sporules which have been described by Dr. Grant. 



Mr. Hogg concludes, if the currents of water do flow in and issue 

 out from the sea sponge, independent of the function of respiration 

 of any marine insect or parasitical animal nestling within it, that 

 then they are caused by the same means which effect the motions of 

 fluids in plants, and that these currents convey nutriment to the in- 

 ner parts of the sponge, after the same manner as food is supplied 

 to vegetables. He observed that neither the odours of the fresh, 

 dried, and burnt sponges, nor the presence of ammonia in them, af- 

 forded proofs of their animality, and that there really is no more pe- 

 culiarity in their chemical composition than what likewise exists in 

 that of certain plants. 



