BOTANY. 293 



desert, which it covers in some parts, and grows during the night, as 

 do many mushrooms. The French soldiers, during an expedition to- 

 wards the south of Constantine, actually subsisted upon it for some 

 days, cooking it in various ways, and even making it into bread. I 

 do not pretend to explain the miraculous portions of the history of 

 the manna, nor the double quantity gathered on the sixth day. There 

 are a few characters in the account given by Moses which disagree 

 with the substance I have presented to you, yet the discovery of a 

 substance springing up in the short space of a night, on the surface 

 of the sandy desert, and that substance capable of sustaining human 

 life, is, to say the least, a remarkable fact, and one well worthy the 

 examination and researches of botanists." 



A NEW SPECIES OF MANNA. 



ALL the mannas are saccharine exudations of plants, and resemble 

 each other very closely in their chemical constitution. Their prin- 

 cipal constituents are gum, sugar, and the substance called mannite, 

 which derives its name from its source, and has been hitherto consid- 

 ered as the peculiar characteristic of manna. Dr. Thomas Anderson, 

 a Scotch chemist, has, however, recently analyzed a specimen of 

 manna from the interior of Australia Felix, which does not contain 

 any mannite. It is found in great abundance on the leaves of the 

 young mallee plant. The natives call it lerp ; it is "very sweet, 

 and is formed by an insect on the leaves of gum-trees; in size and 

 appearance like a flake of snow, it feels like matted wool, and tastes 

 like the ice on wedding-cake." It is very nutritive, and adheres to 

 the leaves so slightly, that it is washed off by rain. In opposition to 

 the opinion, that it is the product of insects, the natives assert that it 

 is the spontaneous production of the mallee or gum scrub, and that it 

 grows on both sides of the leaves. On a chemical examination, the 

 lerp is found to consist of small conical cups, covered externally with 

 a number of white hairs curled in various directions; the hairs are 

 not distributed over the whole external surface, but are usually at- 

 tached to the middle portion. The cups adhere loosely to one an- 

 other by the edges. Under the microscope, each hair is seen to form 

 a uniform tube, presenting a granular structure. The hairs and cup 

 are colored blue when touched by iodine, indicating that they contain 

 starch. The sweet taste is confined to the hairs. In fact it differs 

 both in form and chemical constitution from all other mannas, as has 

 been found by long examination. The question of the origin of the 

 lerp is a subject of great difficulty, for, as it is in part insoluble, we 

 cannot suppose that it exudes from a leaf when punctured by some 

 insect, as is the case with the other mannas. Chemists who have 

 examined it assert that it cannot be the product of an insect, while, on 

 the other hand, some entomologists have gone so far as to establish, 

 on the strength of it, an entirely new genus of insects. Jameson's 

 Journal, July. 



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