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HARDWiCKE'S SCI ENCE- GOSSIP. 



crystalline plates by exposure of the lichen to heat 

 in a covered vessel. A very careful management of 

 the heat is necessary, in order to obtain the best 

 result. If insufficient, there is no product ; if in 

 excess, then the acid is entirely sublimed in exceed- 

 ingly small prisms upon tlie cover of the vessel ; if 

 the heat be exactly of the right degree and kept up 

 a sufficient time, then the acid collects in large 

 plates and spiculaj about the edges of the apothecia, 

 glittering like mica and reflecting every variety of 

 prismatic colour. In this condition the lichen fur- 

 nishes a brilliant object for the microscope. My 

 mode of proceeding to obtain the proper result is 

 to place a portion of the lichen, furnished with ripe 

 apothecia, in a small porcelain dish or watch-glass, 

 which I cover with a bit- of window glass, and then 

 expose to the heat of a small spirit-lamp flame, at a 

 distance of about four inches from the source of 

 heat. The first result, in all probability, will be a 

 deposit of condensed moisture upon the under sur- 

 face of the cover. This may be wiped off, and the 

 cover replaced. If the heat is now of the right 

 degree, small glittering crystals will, in the course 

 of twenty minutes or so, make their appearance 

 about the apothecia, and gradually increase in size 

 under the prolonged continuance of the heat, until 

 the matter yielding them is exhausted. When a 

 good crop has been obtained the operation should 

 be discontinued, otherwise the product might be 

 too far volatilized. The result is exceedingly beauti- 

 ful, and will well repay care and patience in obtain- 

 ing it. These crystals are a delicate test for potash, 

 striking with it a brilliant red colour.— C. /, Mailer, 

 Eastbourne. 



New BKiTisn Elora. — Mr. A. Irvine, of 28, 

 Upper Manor-street, Chelsea, is preparing a new 

 work on the " British Plants," giving a condensed 

 summary of the characters of the orders, genera, 

 and species. x\s he is very desirous to obtain in- 

 formation about all recent additions to the species, 

 and hitherto unpublished localities, he will be glad 

 to receive any assistance on these heads. 



Our Moss Flora.— The Journal of Botany for 

 July contains an excellent article by Dr. Braith- 

 waite, on " Recent Additions to our Moss Flora," 

 Ulustrated by two lithographic plates of the new 

 species. 



The Agassiz Expedition. — American papers 

 state that the Agassiz expedition, at the latest 

 accounts, was off Sandy Point, Patagonia; and that 

 among the scientific curiosities noted by some mem- 

 bers of the party were immense quantities of the 

 largest known alga or seaweed, which grows on 

 those coasts in from 6 to 20 fathoms of water, in 

 vast beds. Patches of this seaweed were passed 

 in open sea, with large sea- lions lying on their 

 surface. 



Manna of the DESERT.-^Slnce the appearance 

 of the article in Science-Gossip of March last, 1 

 have been informed that the paper read by Mr. 

 Munby before the British Association at Birming- 

 ham, in 1819, left an impression (an erroneous one) 

 on the minds of some, that it was opposed to the 

 Biblical account: it may therefore be as well to 

 make a few additional observations, in order to 

 remove any doubts (if such stQl exist) on the sub- 

 ject. All will admit the manna vras miraculously 

 supplied, but there is no more reason to suppose 

 that it was not a natural product than the water 

 which issued from the rock at Horeb, where the 

 miracle consisted in its sudden issuing from the rock, 

 not in the water itself ; so with the quails, which 

 were miraculously seiit, but were natural quails. 

 The statement of Mr. Muuby that the lichen 

 grew up in the night (although afterwards qualified 

 by the expression " springing up ") might, if taken 

 literally, and without qualification, lead to an objec- 

 tion that lichens are plants of slow growth ; some 

 lichens, however (the Collemas for instance), are 

 greatly affected by moisture, so that during the 

 heat of the day, in such a hot climate, they would 

 be "scarcely visible, while in moist weather they 

 would " spring up," swell, and become prominent 

 objects: such would be the effect of a strong dew. 

 Thus, " when the dew that lay was gone, there lay 

 a small round thing," &c., but "when the sun 

 wuxedhot, it melted." (Exodus xvi. 14 and 21.) In 

 like manner the lichens would appear to melt, or, in 

 other words, to shrivel up and almost disappear. 

 An interesting account, and much to the purpose, 

 is given of the lichen by Lindley in his " Vegetable 

 Kingdom." He says : ",The Lichen esculentus some- 

 times appears in immense quantities in Persia, 

 Armenia, and Tartary, where they are devoured by 

 the natives, who fancy that they must fall from 

 heaven, not knowing how to account for the prgdi- 

 gious numbers of the plants, of the origin of which 

 they are ignorant." He adds : " Parrott says that 

 in some districts of Persia they cover the ground to 

 j the depth of five or six inches, and Eversman, who 

 had an opportunity of studying the species on the 

 rivers Ember and Jaik, and also near Lake Oral, 

 was convinced that, even in the earliest stage of 

 growth, the plants have not the slightest attachment 

 even to a grain of sand, but that the thallus is 

 developed freely, as was at first declared by Pallas. 

 A species or variety has lately been found in large 

 quantities in Algiers; and Treviranus informs us 

 that specimens supposed to have descended from the 

 clouds at Mount Ararat, exist in the Museum of 

 Natural History in the Armenian convent of St. 

 Lazzaro, in an island of that name in Venice. The 

 curious production in question is eaten both by 

 men and animals in the several countries extending 

 from Algiers to Tartary. The individual plants 

 weigh from a few grains to two scruples or upwards 



