RECOGNITION OF THE CHARACTER OF SOILS. 



523 



quite commonly just as calcareous as the heavier soils, and 

 show no " silicophile " flora. 



According to the writer's observations and views, it being 

 obvious that some plants are practically indifferent to the pres- 

 ence or absence of lime in the soil except in so far as it influ- 

 ences favorably the physical conditions, moisture must always 

 stand first as the condition of maximum crop production, and 

 as a conditio sine qua non of the best development of plants on 

 all kinds of soils; its best measure being a matter of special 

 adaptation to each species. But this being understood, he 

 agrees with Contejean as to the commanding influence of lime 

 in determining the adaptation of soils to plants, both cultivated 

 and wild. At the same time, it is obvious that the absence of 

 the opportunity to observe really native vegetation, adapted to 

 the soils through ages, has created for European observers 

 difficulties which are readily solved where original native 

 floras are available. 



Schimper x says pointedly that observations prove that the 

 differences between the location of plants on calcareous and 

 siliceous soils are not constant,, but vary from province to 

 province; that c. g., the list of indifferent (bodensteter) plants 

 for the Alps do not hold good in the Dauphine, still less be- 

 tween the Carpathians and Skandinavia. According to 

 Wahlenberg the following species are calciphile in the Carpath- 

 ians, and according to Christ indifferent in Switzerland : 

 Dryas octopetala, Saxifraga oppositifolia, most of the legumin- 

 ous species, Gentiana nivalis, G. tcnclla, G. verna, Erica cornea, 

 Chanucorchis alpina, Carex capillaris. Geum rcptans is re- 

 ported by Bonnier to be exclusively calciphile on Mont Blanc, 

 exclusively silicophile in the Dauphine; indifferent in Switzer- 

 land. A great number of similar contradictions are reported 

 by others as well, and the entire subject thus becomes rather 

 vague ; so that Schimper and others suggest that climatic con- 

 ditions may in part be responsible for these discrepancies. 



In all, or nearly all these cases, it is tacitly assumed that the 

 underlying geological formation has essentially been the source 

 of the soil, and that its character is determined accordingly. 

 But this assumption is wholly arbitrary unless confirmed 

 by actual direct examination. A soil-formation overlying 



1 Pflanzengeographie, p. in & ff . 



