FOREIGN COHRESPONDEi;CE. 
2ti3 
hellidifolia, L. ; Silene acaulis, L. ; Potentilla fngida, Will. ; Phyteuma 
hemisphcericiim, L.; Erigeron mnflorum, L. ; Fi/ret/irum alpinu7n,W\\ld. ; 
Sarifraga brydides, L. ; S. Groenlandica, Lap. ; S. musco'ides, Martins ; 
Androsace Helvetica, Gaud. ; A. puhescens, D. C. ; Gentiana verna, L. ; 
Luzida spicata, D. C. ; Festuca Ilalleri, Will. ; Poa laxa, Haeuke. ; 
P. coesia, Sm. ; Agrostis rupestris, 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, siiows us, on a space of ground infinitely larger, only 82 
species of jAanerogamic plants. 
On the Alps plants arc warmed by the soil in which they grow far 
more than by the air which surrounds them ; a bright liglit favours 
their respiratory functions ; 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 flourisli 
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- 
Bphere 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. Favoured 
by Count IMarschall, of Vienna. 
1. — •Metalliferous Strata of Rochlitz, on the Southern Slope of the 
Bohemian Siulets. 
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 cii'cumstances. 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 
