FOREIGN CORRESFONDEKCE. 



283 



hellidifolia, L. j Silene acaiilis, L. ; Potentillafrigida, Will. ; Phyteuma 

 hemisphcericinn, L.; Erigeron iiniflorum, L. ; Pyrethrum alpinum,y^\\\d.. 

 Saxifraga hrydides, L. ; S. Groenlandica, Lap. ; iS'. mus,cdides^ Martins ; 

 Androsace Helvetica, Gaud. ; A. piibescens. D. C. ; Gentiana verna, L. ; 

 Luzula spicata, D, C. ; Festuca Halleri, Will. ; Poa laxa, Haenke. ; 

 P. coesia, Sm. ; Agrostis riqoestris, All. ; and Carex nigra, All. 



Also, on the 28tli June, 1846, the temperature of the air in the 

 shade being 9^ 4' (centigrade), and in the sunshine 11° 4', the schistose 

 gravel in which these plants grew showed a temperature of 29°. 

 Spitzbergen, the shores of which may also be said to touch upon the 

 snow-line, shows us, on a space of ground infinitely larger, only 82 

 species of phanerogamic plants. 



On the Alps plants are warmed by the soil in which they grow far 

 more than by the air which surrounds them ; a bright light favours 

 their respiratory fimctions ; and so soon as the temperature descends 

 to zero during the day a layer of recent snow preserves them from the 

 accidental cold which generally accompanies bad weather on high 

 mountain-ranges. Equally sensitive to cold and to heat, they can 

 only endure a temperature ranging from 0'' to + 15°. Continually 

 moistened by the damp clouds and the wet which drops from the 

 melting snow, they would require the most careful culture to flourish 

 in the plains below, for the horticulturist would have to protect them 

 at once from the chills of winter and the heat of summer, giving them 

 constant humidity and bright light. 



At Spitzbergen, on the contrary, in spite of the perpetual day 

 which reigns during the summer, vegetation is poor and scanty, 

 because the sunbeams, mostly absorbed by the great depth of atmo- 

 sphere they traverse, and by the continuous mists, have not power to 

 vivify by their light or by their warmth its icy ground. 



Notes read before the Imperial Geological Institute of Vienna. Favom^ed 

 hy Count Marschall, of Vienna. 



1. — Metalliferous Strata of Rochlitz, on the Southern Slope of the 

 Bohemian Sudets. 



The author of a monograph on these strata is the lately deceased 

 Mr. E. Forth, who in 1853 successfully undertook the re-opening of 

 the old mines in this district, abandoned some centuries ago under the 

 pressure of unfavourable circumstances. The ores occur in a series of 

 calcareous strata, intimately connected with the schistose quartzite of 

 the micaceous and argillaceous schists of the South Sudets, and under 

 circumstances analogous to those of the Scandinavian metalliferous 

 deposits. Large masses of a mineral substance, similar to malacolite, 

 are impregnated with sulphurets of copper, lead, zinc, and iron. With 



