Arctic Natural History. 81 



for their small size. The climate is so unfavourable that 

 gigantic algse, such as occur in more favoured regions, can- 

 not exist; the organisms in question, the representatives of 

 the individual cells of which the larger species are composed, 

 supply their place, and the siliceous matter which they have 

 the power of separating from the medium in which they live, 

 renders them better fitted to resist the injuries to which they 

 are exposed. — (Sutherland's Journal.) 



12. Nostoc Arcticum, Berk. By Dr Dickie. 



This species has been recently described by the Bev. M. J. 

 Berkeley, in a paper read before the Linnean Society. He 

 refers it to Hormosiphon, expressing a doubt whether the 

 latter genus is anything but a young or abnormal state of 

 Nostoc. It appears to grow in great profusion in the loca- 

 lities where it occurs, and Dr Sutherland communicates the 

 following notes respecting it : — 



" It grows upon the soft and almost boggy slopes around 

 Assistance Bay ; and when these slopes become frozen, at 

 the close of the season, the plant lying upon the surface in 

 irregularly plicated masses becomes loosened, and if it is not 

 at once covered with snow, which is not always the case, the 

 wind carries it about in all directions. Sometimes it is blown 

 out to the sea, where one can pick it up on the surface of 

 the ice, over a depth of probably one hundred fathoms. It 

 has been found at a distance of tjvo miles from the land, 

 where the wind had carried it. Each little particle lay in a 

 small depression in the snow, upon the ice : this tendency to 

 sink commenced early in June, owing to the action of the 

 sun. At this distance from the land it was infested with 

 Podurse ; and I accounted for this fact by presuming that the 

 insects of the previous year had deposited their ova in the 

 plant upon the land, where, also, the same species could be 

 seen in myriads upon the little purling rivulets, at the sides 

 of which the Nostoc was very abundant." 



Dr Sutherland found this plant to be edible, and superior to 

 the Tripe de Roche, in connection with which it may be wor- 

 thy of remark here, that Nostoc edule (Berk. & Mont) is 



VOL. LIV. NO. CVII.— -JANUARY 1853. F 



