234 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



alpine plant life. The decomposing granite or the decomposing 

 schists, especially those containing a large amount of mica, seem 

 to resist the action of the sun's I'ays, as they appear to hold the 

 moisture, and only admit of slow evaporation, consequently the 

 temperature, although falling low, does not fall suddenly. Then 

 another item to be considered is the fact that the moisture being 

 so near the surface of this porous soil, when the temperature falls, 

 dew will be formed much faster, thereby causing protection to 

 the plants in modifying the effects of low temperatures. This is 

 markedly seen in many plants when we compare the flora of the 

 schists with those of the granites. Take Saxifraga rivtdaris for 

 instance, on the schists of Lawers, or by the sides of the streams 

 in the Dovrefjeld, in Norway, it attains only about one inch in 

 height, while on the granite of Lochnagar it reaches the height of 

 four or five inches. I^oa alpina on the schists is found as a rule 

 in single plants, while on the granites it is found in tufts, but in 

 these cases the method of decomposition appears to have much 

 greater influence than the chemical constituents of the rocks. 



In spite of the efforts of many geologists and botanists too, to 

 fix certain alpine plants to certain rock formations, these theories 

 have never, in my opinion, been proved from actual alpine 

 experience. Suppose the fine range of mountains under review 

 had been composed of another formation, granite with limestone 

 outcrops, for personal preference. I have no doubt that they 

 would have been richer than they are in arctic or arctic-alpine 

 plants. Calluna vulgaris grows luxuriantly on the sand by the sea 

 shore near to fresh water, the nidus here being destitute of lime. 

 Sphagnum grows to great perfection on the rocks overhanging the 

 sea in some of our Western Islands, where again no lime is 

 present, and the same might also be said of Vaccinium myrtillus, 

 Sarothamnus scoparius, Rumex acetosella, and Digitalis purpurea. 

 If traces of lime are to be found, they are very weak. Again 

 Heliarhthernurn vulgare and Anthyllis vuhieraria will only grow 

 where there is a strong percentage of lime, and all over the tract 

 of country we have been speaking of, the bracken seems to grow 

 whenever we can trace lime in the soil. No so-called limestone 

 plants are found on the limestone in Cornwall. But this only 

 goes to prove that the difference between a limestone flora and a 

 silica flora is not so great as the difference between a halophytic 



