Prof. H. James-Clark on the Spongije ciliata3. 133 



XXI. — Notulce LichenoJogicce. No. XX. 

 By the Rev. W. A. Leighton, B.A., F.L.S. 



Every lichenist is unfortunately well aware of the great diffi- 

 culty of preserving specimens of lichens which grow on the 

 earth. Too frequently he finds, on consulting his herbarium, 

 that the earth on which such lichens grew has become dry 

 and crumbled into dust, involving in such disintegration the 

 destruction of the lichen itself, especially when this happens 

 to possess a crustaceous thallus. To remedy this a solution 

 of gum arable has been sometimes used, but with partially 

 satisfactory results only, inasmuch as the mucilage does not 

 penetrate the earth, but only conglomerates its surface. An 

 etFective preparation appears to have been discovered by 

 M. J. M. Norman, of Tromso, Norway. It consists of a solu- 

 tion of isinglass in spirits of wine, such as is used in the pre- 

 paration of English adhesive plaster, which a chemist informs 

 me is better known as '^ Front's plaster." This composition, 

 when liquefied in a vessel plunged into water of the tempera- 

 ture of 25°-30° C, is greedily imbibed by the earth on which 

 the lichen grows, and becomes inspissated into a solid gelatine 

 at a temperature below 15°. The solution may be applied by 

 a camel's-hair pencil until the earth becomes saturated ; but 

 care should be taken that the lichen itself be not moistened 

 with it, for otherwise it would become discoloured. When the 

 surface has become dry, the specimen may be submitted to 

 moderate pressure, which, after some days, produces the requi- 

 site hardness and tenacity. The favourable experience of 

 some years encourages M. Norman to recommend this prepa- 

 ration to his fellow lichenists. 



XXII. — On the Spongiffi ciliatoe as Infusoria flagellata; or 

 Ohservations on the Structure, Animality, and Relationshij) 

 of Leucosolenia botryoides, Boioerhank'^ . By H. James- 

 Clark, A.B., B.S., Professor of Natural History in the 

 Agricultural College of Pennsylvania f. 

 [Plates v., VI., VII.] 

 I HAVE been engaged like others, for some time past, in en- 

 deavouring to clear up the doubt which prevails in the scien- 



* A sketch of tlie contents of tliis memoir has abeady heen puhlished 

 in the ' Proceedings of the Boston Society ' for June 20, 1866 ; the ' Ame- 

 rican Journal of Science ' for November 18G6, and in the ' Annals ' for 

 January 1867. 



t From a separate impression from the ' Memoirs read before the Bos- 

 ton Society of Natural History,' vol. i. part 3 ; communicated by the 

 author. 



