448 Ecology 



snow, but others arc distinct types. Fritsch points out that most of the 

 members of this yellow snow-flora contain a large amount of a solid fat and 

 that the yellow pigment which gives the colour to the snow is present in this 

 fat. The presence of the fat is probably an adaptation against the intense 

 cold of the habitat and thus functions like ha?matochrome, which is capable 

 of absorbing the heat-rays of the sun. 



Green snow differs but little from yellow snow. It has been described 

 from the Alps and from the Arctic. Its constituents are mostly Green Algse : 

 the zoogonidia of Chlamydomoiias nivalis, Ankistrodesmus nivalis and species 

 of Mesot&nium. A few members of the Myxophycere also occur. On the 

 Glacier d'Argentiere Ankistrodesmus Vireti is one of the constituents of 

 the green snow-flora (Chodat, '09). 



Brown snow has been described by Wittrock and it owes its colour to 

 numberless fine mineral particles with which are mixed Mesot&nium (Ancylo- 

 nema) Nordenskioldii (which contains phycoporphyrin in its cell-sap), several 

 other Green Algse, various diatoms and a few Myxophycese. 



Lastly it should be mentioned that Chodat ('02) has referred to black 

 snow (neige noir), the principal Alga in which is Scotiella nivalis (Fritsch, '12). 

 Scherffel ('10) also records Rhaphidonema brevirostre as a constituent of black 

 snow in the high mountains of Tatria. 



LITERATURE CITED 



APSTEIN, C. ('96). Das Susswasserplankton. Mcthoclc und Resultate dcr quantitative!! 



Untersuchung. Kiel mid Leipzig, 1896. 

 BACHMANN, H. ('07). Vergleichende Studien iiber das Phytoplankton von Seen Schottlands 



und der Schweiz. Arcbiv fur Hydrobiologie und Planktonkunde, iii, 1907. 

 BACHMANN, H. ('11). Das Phytoplankton dos Siisswassers mit besondcrer Beriicksichtigung 



des Vierwaldstiittersees. Jena, 1911. 

 BRUNNTHALER, J. ('00). Plankton-Studien, I. Das Phytoplankton des Donaustrorues bei 



Wien. Verhandl. der k. k. zool.-botan. Ges. in Wien, 1, 1900. 

 CEDERGREN, G. R. ('13). Bidrag till Ka'nnedomen om Sotvattensalgerna i Sverige. I. 



Algfloran vid Upsala. Arkiv for Botanik utgif. af K. Sv. Vet.-Akad. xiii, no. 4. 



Stockholm, 1913. 



CHODAT, R. ('96). Flore des neiges du col des Ecandies. Bull, de P Herb. Boiss. iv, 1896 

 CHODAT, R. ('02). Algues Vertes de la Suisse. Berne, 1902. 

 CHODAT, R. ('09). Sur la Neige verte du Glacier d'Argentiere. Bull, de la Soc. botan. do 



Geneve, 2 me ser. i, 1909. 

 DAKIN, \V. J. & LATARCHE, MARGARET (13). The Plankton of Lough Neagh. Proc. 



Roy. Irish Acad. xxx, ^ect. B, no. 3, 1913. 

 DELF, E. M. ('15). The Algal Vegetation of some Ponds on Hampstead Heath. New 



Phytologist, xiv, 1915. 



ENTZ, G. ('04). In Result, der wiss. Erforschung des Balatonsees, ii, Budapest, 1904. 

 FRITSCH, F. E. ('02). Preliminary Report on the Phytoplankton of the Thames. Ann. 



Bot. xvi, 1902. 



