172 Analysis of Scientific Books and Memoirs. 



tion, on board the Alexander, who expressly states, that the Red Snow 

 was never more than one or two inches below the surface. The remark 

 made in Italy, that the White snow fell as well before as after the Red, 

 may be easily explained, by what has been said before. We shall, too, 

 account for the great extent cf country which it covered in one night, bet- 

 ter from supposing a cause to act upon an homogenous surface, than by 

 supposing, that the Red Snow fell in one night over the whole mountain- 

 ous parts of Italy. 



That this snow was seen after only one night I have in part accounted 

 for, by observing, that its red colour could not be noticed before it was 

 formed into sufficient masses; and its rapid appearance will the less sur- 

 prise those naturalists who are accustomed to examine the Infusoria, and 

 who well know how quickly an innumerable multitude of these beings can 

 be produced under favourable circumstances. 



It now remains for us to determine, as correctly as possible, the nature 

 of these minute bodies, about which opinions are so much divided. 



The idea of De Saussure, that the colouring substance of the Red Snow 

 is the farina of a plant, deserves but little attention, as there is no plant 

 which has the farina, or p:llen, of that colour. De Saussure, indeed, en- 

 deavours to strengthen his opinion, by saying, that the farina may have 

 changed its colour from the intensity of the light upon the Alps; but al- 

 lowing this to be possible, chemical analysis is in opposition to it. 



The opinion of Mr Rauer has greater weight with us, namely, that the 

 Red Snow is a Fungus. Yet, still, I cannot agree with him. The fungi 

 are the offspring of darkness, and are never formed or kept in water. They 

 rather prefer a close and moist air, are produced by putrid substances ; 

 properties the very reverse of what we know of the Red Snow ; which is 

 formed in the purest waters, with the strongest light, in the clearest at- 

 mosphere, and without any previous decay. 



That which Baron Wrangel has described, and which I have shown to 

 be identical with the Red Snow, he considers to be a Lichen of the genus 

 Lepraria, a conclusion to which he may have been led by the crustaceous 

 covering which this plant forms upon limestone. This crust, however, I 

 take to be a sediment that is deposited on the evaporation of the water ; 

 and De Saussure's observation, according to which it is also formed on the 

 melted snow, shows, at the same time, that it is not peculiar to stones. 

 To this it may be added, that the sporules of the genus Lepraria have a 

 different form, and yield a different chemical analysis from the globules of 

 the Red Snow. 



Hence it follows, that this substance must be either an Alga or an Ani- 

 vialcula, between which I know no certain limits. There are forms 

 amongst them which may, with equal propriety, be ranked with either or 

 both. There are Alga; which become Animalcules, and vict versa. Last- 

 ly, there arc Infusoria, which, at one period of their existence, are endow- 

 ed with the power of movement, while, at another, they exist only in the 

 character of a vegetable. 



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