Linnaan Society. 285 



in his recent work entitled ' Recherches sur THydre et TEponge 

 d'Eau douce,' Paris 1844, in which the discovery of the locomotive 

 germs of the freshwater sponge is apparently claimed by the author 

 as his own. 



Mr. Hogg then proceeds to remark on the discrepancies of authors 

 with regard to the existence of cilia on these bodies, and on the 

 spores of the Ectosperma. He accounts for his having overlooked 

 them in the Spongilla, on the supposition that the germs which he 

 observed under a very high power of the compound microscope had 

 reached the period when, as M. Laurent states, *' ils perdent leurs 

 cils pour toujours," and notices that it appears, from M. Thuret's 

 recent observations, that the same circumstance occurs in the spores 

 of the Ectosperma. This resorption or disappearance of the cilia 

 after a certain period will readily account for the denial of their ex- 

 istence by practised microscopical observers. 



The existence of cilia subservient to locomotion is far from deter- 

 mining, in Mr. Hogg's opinion, the question of the animal nature of 

 the bodies to which they belong, although the zoocarpic theory, 

 which he regards as most improbable, appears to be still gaining 

 ground. He believes the motive power of the cilia of the sporules 

 of Spongilla and the AlgcE, as also of the Sea- Sponges, to be depen- 

 dent on some peculiar organization not connected (as in the loco- 

 motive gemmules of a zoophyte) with any muscular apparatus ; un- 

 less indeed, as he has before suggested, mere endosmosis and exos- 

 mosis should be found sufficient to produce it. 



For these and other reasons which are detailed in his paper, Mr. 

 Hogg still believes both the River and Sea-Sponges to be vegetable 

 productions, and thinks that " until they shall be discovered to pos- 

 sess a stomach or a gastric sac, no zoologist can possibly consider 

 them to belong to the Animal Kingdom." 



January 21, 1845. — R. Brown, Esq., V.P., in the Chair. 

 A Note was read, addressed to the Secretary, by John Curtis, Esq., 

 F.L.S. &c., containing the description of a cocoon of the Emperor 

 Moth (Saturnia Pavonia-minor), which on being longitudinally divided 

 was found to have internally, in place of the chrysalis, a series of 

 cells so analogous to those represented by Mr. Curtis in the nine- 

 teenth volume of the Society's * Transactions,' plate xxxi. fig. 5, as 

 to leave no doubt on his mind that the woolly masses there exhibited 

 are the cocoons of some large South American Bomhyx, and that the 

 substance of the caterpillar has been converted into cells by the larva 

 of the Tenthredinidous insect. But although the theory of the nest 

 there figured having been constructed by an insect of that family is 

 thus set aside as erroneous, it is only to make evident a still greater 

 anomaly in its economy, viz. that its larvae are parasitic. In the 

 present instance Mr. Curtis was unable, after the most rigid scrutiny, 

 to find any vestige of a perfect insect. A dried and broken maggot 

 was all that could be perceived, and its fragments on being put to- 

 gether bore more resemblance to the larvae of the Ichneumonidce than 

 to those of the Tenthredinidis. 



