868 



merely in the infant state ; and consequently if the genus Hormosi- 

 phon is to be retained, the Arctic species must be regarded as belong- 

 ing to it, for no such appearance has been detected by Mr. Berkeley 

 either in dried or freshly-gathered specimens of Nostoc commune. It 

 is possible that more extended observation may show that this cha- 

 racter is not of the consequence attributed to it by Kutzing ; but in 

 the mean time Mr. Berkeley characterizes these specimens as — 



HoBMOsiPHON ARCTicus, foliaceo-plicatus viridis vel fuscescens, filis demura 

 (gelatina dififusa) liberis. 



Fronds foliaceous, variously plicate, sometimes contracted into a 

 little ball. Gelatinous envelope at length effused ; connecting cells 

 at first solitary, then three together ; threads (which are nearly twice 

 as thick as in Nostoc commune) breaking up at the connecting cells, 

 so as to form two new threads, each terminated with a single large 

 cell, the central cell becoming free. Of these threads and of their 

 gelatinous envelope Mr. Berkeley gives figures. 



With regard to the Thibetan Nostoc, Mr. Berkeley adds that a 

 species of this genus, as is well known, is a native of Tartary and is 

 eaten abundantly in China. There is a box of it, sent by Mr. Tra- 

 descant Lay, in the Museum of the Linnean Society ; and mention is 

 made of it by M. Montague in the ' Revue Botanique,' ii. p. 247, as 

 having, in the form of a soup, made part of a dinner given by the 

 Mandarin Huang at Macao, to several members of the French Em- 

 bassay. The Mandarin described it as a freshwater plant, growing in 

 Tartary in streams and running water, and sold at Canton in small 

 boxes : it is highly esteemed by the Chinese, and not very expensive. 

 At this time M. Montague regarded the species as Nostoc caeruleum, 

 but specimens sent him by Mr. Berkeley proved it to be distinct, and 

 it was afterwards published in the * Revue Botanique ' under the name 

 of Nostoc edule. Berk, and Mont., and figured by Kutzing in his 

 ' Tabulae Phytologicae.' In the last-named author's ' Species Alga- 

 rum,' it is said to have been gathered by Gaudichaud, who,, although 

 a great traveller, was certainly never in Tartary. The Thibetan Nos- 

 toc, like the Arctic, is probably quite as good as the Tartarian. After 

 some further notes on the chemical changes produced in this plant 

 and in Nostoc commune when treated with iodine and sulphuric acid, 

 and a reference to a passage in Kutzing's ' Grundziige der Philoso- 

 phische Botanik,' where he speaks of these plants as consisting in 

 great measure of gelacin (a substance belonging to the same category 

 as bassorin, and perhaps a modification of it), Mr. Berkeley concludes 



