28 Transactions of the Society. 



VI — The "Bed Snow" Plant (Sphccrella nivalis). 

 By G. S. West, M.A., D.Sc., F.L.S. 



{Read February 17, 1909.) 



The red coloration of extensive tracts of perpetual snow in 

 alpine and arctic situations is caused by a small alga known as 

 Sphcerella nivalis Sommerf. It belongs to the sub-family Chlamy- 

 domonadere of the Volvocacese, and is very closely related to 

 8. lacustris (Girod.) Wittr. (= Ecematococcus pluvialis Flotow),the 

 tiny alga which so often gives a red colour to drying-up rain-water 

 pools and tanks. 



It is in the resting stage of the alga that the red pigment 

 is chiefly developed, and therefore the beautiful red coloration 

 of the snow, which sometimes causes the admiration and astonish- 

 ment of the traveller and explorer, is due to the presence of 

 myriads of the resting-cells of Sphcerella nivalis. 



There are no authentic records of " red snow " in the British 

 Islands due to this alga, and, owing to the peculiar physiological 

 conditions necessary for the completion of its life-cycle, it is 

 scarcely likely that it will be found. It occurs in the Austrian, 

 Swiss, and Italian Alps, and in Norway, the red tinge appearing 

 towards the month of August. It has also been found amid the 

 perpetual snows of other regions, more especially in the South 

 American Andes, and in the arctic and antarctic snow-fields. 



It possibly occurs throughout most of the arctic snow-fields, 

 and the present article was written on the examination of some 

 particularly fine resting-cells recently presented to the Society by 

 the Peary Arctic Club. 



Each resting-cell is a small globular body (17-24 y, in diameter), 

 consisting of a protoplast inclosed in a fairly thick wall of cellulose. 

 Pyrenoids and a nucleus are present, but are hidden by a red 

 pigment known as " hsematochrom," which permeates the whole 

 protoplasm, and exists partly in solution in minute drops of oil, 

 and partly in a microcrystalline form. A small quantity of 

 chlorophyll is also present, even in the purely red cells. The 

 exact function of this hrematochrom is a perplexing problem. It is 

 certainly more stable than chlorophyll, and generally accompanies 

 diminished vitality, which fact accounts for its presence in the 

 resting-cells. The cells can thus probably exist through adverse 

 circumstances much better than if they were merely green, not 



