THE EFFECT OF SOILS 117 



At first sight it might appear that the nature of 

 the soil may be a controlling element in determining 

 the distribution of a species. Some plants appear to 

 occur in Switzerland only where granite or schist 

 forms the rock from which the soil is derived. Others 

 seem to frequent only limestone soils. A third set of 

 plants appear to be quite indifferent as to soil. We can 

 thus distinguish three groups : the calcicoles, confined 

 to limestone soils ; the calcifuges, which occur only 

 where lime is absent from the soil ; and a third, those 

 which are indifferent as to soil. 



It is frequently asserted that the white-flowered 

 Anemone alpina occurs on all sorts of soil, while the 

 still commoner variety with yellow flowers, often called 

 Anemone sulphur ea, is only to be found on non- 

 calcareous soils. Again, the rarer Hairy Alpenrose 

 {Rhododendron hirsutum) is believed to be calcicole, 

 whereas the commoner species, Rhododendron ferru- 

 gineum, is indifferent in its tastes. The Auricula 

 {Primula auricula) is also stated to l^e calcicole. 

 It is true that in many localities this is the case. 

 The Auricula, for instance, flourishes exceedingly 

 on the limestone rocks of the Engstlen Alp (Canton 

 Berne). But from a botanical standpoint, in order 

 to estimate the absolute effect of the constituents 

 of a soil, as factors controlhng the distribution of 

 plants in the Alps, it is of importance to know 

 whether each species is always restricted to one 

 particular soil. 



Professor Bonnier, whose work wo have already 



