Blood-red Colour of Water. 135 



they collect in masses, and thus produce the red -coloured 

 patches. 



In melting snow, we in general observe, every year, that al- 

 though it appears dazzlingly white before it melts, yet it may 

 soon be perceived during its melting, to disclose traces of dust 

 which has been mixed with it by the motion of the atmosphere, 

 and which gradually assumes a darker earthy hue, and at length 

 produces a spotted black surface. It is very probable that the 

 snow-plant, during sunshine, may still farther develope itself 

 and increase. 



Most botanists agree in this, that these bodies belong to a 

 kind of Alga. Bauer alone says that they are of a mushroom 

 form, of the genus Uredo ; and Wrangel, that they are of the 

 lichen form, of the genus Lepraria. The observations of 

 Wrangel are too convincing to be overlooked. Agardh has 

 looked upon the matter m the same light ; but it appears to me 

 that with these must be conjoined the observations of the Prior 

 Biselx of St Bernhard, Charpentier, Meisner and Chladni, and 

 which throw into the back ground the doctrine of equivocal 

 generation. The idea of infusory animals is to be entirely re- 

 jected. 



The preservation of these red bodies in snow-water for the space 

 of five years, according to the testimony of Agardh, seems to me 

 opposed to the nature of alga, and would rather prove that they 

 are bodies which do not belong to the element of algae, and 

 which do not develope themselves in it. As land vegetables, 

 they belong either to the lichen or the mushroom. The sim- 

 plicity of the structure ranks them closely with the mushrooms, 

 and no good reason appears why they may not be denominated 

 Lepraria nivalis. In my Silvis Mycologicis I proposed this 

 arrangement, and I have, after frequent repeated observation, 

 still the same idea. 



At the commencement of the year 1819, Chladni wrote liis 

 celebrated work on fiery meteors, which I here particularly re- 

 fer to. He was at that time acquainted with the chemical ana- 

 lysis of the substance in Thomson's Annals of Philosophy, 

 January 1819, and with Bauer's botanical explanation of the 

 colouring body. The former, which proceeded from the con- 

 jecture that the substance might be bird's mute, to which the 



