- [Footnote: surrounding snowy covering, and which may possibly be
warmed by heat ascending through open fissures. I have already spoken of the Saxifraga boussingaulti, which is found on the Chimborazo at an elevation of 14800 (15773 E.) feet; in the Swiss Alps, Silene acaulis has been seen at a height of 10680 (11380 E.) feet, being in the first-named case 600 (640 E.) feet, and in the second 2460 (2620 E.) feet above the limit of the snows, that limit being taken as it was in the two cases respectively at the time when the plants were found.
In our European Coniferæ, the Red and White Pine shew great and remarkable differences in respect to their distribution. While in the Swiss Alps the Red Pine (Pinus picea, Du Roi, foliis compresso—tetragonis; unfortunately called by Linnæus, and by most of the botanists of the present day, Pinus abies!) forms the upper limit of arborescent vegetation at a mean height of 5520 (5883 English) feet, only an occasional low growing mountain-alder (Alnus viridis, Dec., Betula viridis, Vill.) advancing now and then still nearer to the snow-line; the White Pine (Pinus abies, Du Roi, Pinus picea, Linn., foliis planis, pectinatodistichis, emarginatis) ceases, according to Wahlenberg, more than a thousand feet lower down. The Red Pine does not appear at all in the South of Europe, in Spain, the Appennines, and Greece; even on the northern slope of the Pyrenees it is seen only, as Ramond remarks, at great elevations, and is entirely wanting in the Caucasus. The Red Pine advances in Scandinavia farther to the north than the White Pine, of which last-named tree there is in Greece]*
