Prof. Meyen on Red and Green Snow, 245 



tion of the muscular annection of the animal to the shell. 

 The animal observed by Valenciennes may very possibly be 

 a different species, as the non-serrated margin of the snout and 

 its perfectly corneous state would lead us to believe. 



XXX. — On Red and Green Snow, By the late Prof. Meyen*. 



M. Ch. Martius, who twice accompanied the French expe- 

 dition to Spitzbergen, has given us some interesting observa- 

 tions on coloured kinds of snow, which throw quite a new 

 light on this subject. On the occasion of speaking of the 

 structure and development of the cells of plants in his treatise, 

 ^ Du microscope, et de son application a I'etude des ^tres or- 

 ganises, et en particulier a celle de Futricule vegetale et des 

 globules du sang,^ Paris, 1839, 4to, p. 19, he brings forward 

 the several simple orders of Algae the individuals of which 

 consist of solitary vesicles, and there Protococcus viridis and 

 nivalis are mentioned as the simplest plants ; and the descrip- 

 tion of a green field of snow is given, which was seen on the 

 coast of Spitzbergen on the 25th of July, 1838, by MM. Mar- 

 tins and Bravais. The surface of the snow w^as white, but a 

 few centimetres below it was as deeply coloured as if it had 

 been sprinkled with a decoction of spinage. In another in- 

 stance M. Martins found this green substance scattered like 

 dust over the surface of a snow-field, the greater part of which 

 was covered with an immense mass of Protococcus nivalis ; 

 below the surface and on the edges of the field the snow was 

 also coloured green. 



The microscopical examination was made in Paris, and it 

 was found that the snow-water was filled with an amorphous 

 green matter, among which were spherical Protococcus cells ; 

 some were red and much larger than the green ones, and 

 others were rose-coloured, and as far as size goes stood between 

 both. Later researches showed that the snow was composed 

 of globules, which varied much in size and colour; some ap- 

 peared to be simple, green or pale rose-coloured, and 0*01 to 

 0*05 millimetres in diameter ; others, which were however 

 scarcer, were blood-red and 0*02 mill, in diameter. Other 

 globules appeared to be compound, for they appeared like a 

 case in which other globules were enclosed ; their diameter 

 was 0*05 to 0*055 mill. : in one globule there were 5 red small 

 ones, and M. Martins never saw green ones enclosed in this way. 



From many observations M. Martins came to the conclusion, 

 that the red globules of the green snow are identical with 

 those of the red snow, and that the green snow {Protococcus 



* From Wiegmann's Archiv, Heft i. 1840, p. 166, communicated by H. 

 Croft, Esq. 



