228 THE ALPINE FLORA 



it is rich in lime, and the plants upon it are lovers of 

 chalk. Among granitic mountains silica predominates, 

 and the flora consists, in degrees more or Jess marked, 

 of the species which reject the chalk and choose the 

 silica. In dolomitic countries, where the chalk is impreg- 

 nated with magnesia, a corresponding vegetation is 

 found, and the parallel may be extended indefinitely. 



Alpine flora, then, is divided, according to its chemical 

 affinities, into two great groups, the chalk-lovers and 

 the silica-lovers; other types fall under one or other of 

 these categories. Chalk appears to have so far the greatest 

 influence on the distribution of plant-life, that its pres- 

 ence or absence seems to be the determining cause of 

 the presence or absence of any particular species. Not 

 that the influence of silica is not almost as important 1 . 

 Later we shall see how Gentiana acaulis has taken on 

 modifications of the typical form, in adapting itself to the 

 chemical composition of the soil where it is growing. 

 And the same holds good of a fairly large number of 

 species, especially in our alpine flora. For this reason, in 

 order to make a comprehensive observation and study of 

 the whole range of alpine vegetation, two alpine gardens 

 have been established in Switzerland, one, la Unnsza, on 

 siliceous soil, the other, la J^ambertia, on chalk. Growth 

 in the two gardens is very different; indeed it cannot 

 but differ; and it is most interesting to watch the 

 behaviour under cultivation of chalk-loving species at 

 Linnaea and of chalk-rejecting ones on the Rochers de 

 Naye. 



1 Consult Dr. Magnin's great work, "La Vegetation de la region 

 lyonnaise. 



