The Scottish Naturalist. 125 



snow to be at - 3 2 C. ( = - 25 y 2 ° F.), and the air at the same to be 

 at- 35 C. ( = -31 F.). But at another period they enjoy per- 

 petual light ; and during this period the sun's rays, though falling 

 very obliquely, exercise a powerful influence. At midday the tem- 

 perature in the sun, in a sheltered spot, is very high. Nordens- 

 kiold found that the warmth of the air a short distance above the 

 surface of the ice at midday in July rose to 25 or 30 C. (= 77 

 or 86° F.). With temperatures like these, it is evident that a great 

 melting of the surface of the glaciers and fields of snow must take 

 place. The water thus formed from the snow and ice, though not 

 much above o°C. ( = 32° F.), ie, s the freezing point of water, is 

 amply sufficient to satisfy the demands for warmth of this class of 

 organisms, which may be considered among the simplest in the 

 vegetable kingdom. Though we may be inclined to look upon 

 the conditions of their existence as singularly hard, yet they 

 evidently thrive under them in a most remarkable manner. "Pro- 

 bably," it is remarked, "there is no other species on earth which 

 is richer in individuals than red snow." Dr. Wittrock gives 

 descriptions of several of these plants, including, where known, 

 their fructification. The chief general characteristics of this singular 

 flora of snow and ice may be briefly indicated. It consists 

 almost entirely of microscopic algce, of extremely low organization; 

 most of the species are unicellular ; sometimes they are solitary ; 

 at other times they occur in colonies. The fructification is asexual 

 and of one kind. They are generally of bright colours. The 

 " snow-flower" is blood-red ; Ancylonema Nordenskjoldii, purplish- 

 brown ; many Confervece and Desmidiece, are bright green. 



The genera and species which are known to occur are shown in 

 the accompanying table, which was drawn up by Professor 

 Wittrock. It is interesting as showing the Ice flora separately 

 from the Snow flora. Many more species are found on snow than 

 on ice ; their proportion is nearly four to one. The most com- 

 mon plant is the red snow ; next to it is Aficylonema Nordenskjoldii. 

 The latter species is found on ice only, and indeed is the only 

 species absolutely confined to ice. There are only two species 

 of Phycochromophycece on ice, while ten species are found on snow. 

 The snows of Spitzbergen are rich in Confervece ; while those in 

 Lapland are rich in Desmidiece. In the middle north the Phyco- 

 chro?ns prevail. Bacterium Termo is occasionally found within 

 the limits of the ice and snow flora ; and Chytridium Hccmatococci 



