524 SOILS. 



limestone on the slopes of a range may be wholly derived from 

 non-calcareous formations lying at a higher elevation, or may 

 have been leached of its original lime-content by abundant 

 rains. The feldspars constituting rocks designated as granite, 

 may or may not be partially or wholly of the soda-lime in- 

 stead of the potash series ; the mica may or may not be partially 

 replaced by hornblende, in which cases the soil would be cal- 

 careous to the extent of determining the character of the flora 

 as calcifuge or calciphile, without its being at all evident in the 

 physical character of the soil, which would still be " granitic " 

 or " siliceous." Such observations in order to be critically 

 decisive, clearly require that the observer should be, not merely 

 a systematic botanist, nor a mere geologist or chemist, but all 

 these combined. There is good reason to believe that most or 

 all of these supposed contradictions would disappear before a 

 critical physical and chemical examination of both the soils and 

 the rocks from which they are supposed to have been derived. 

 Contejean himself, in placing so many of his long catalogue of 

 plants into the doubtful groups, suggests many cases in which 

 the above considerations may explain the apparent dis- 

 crepancies. 



What is a calcareous soil? The definition adopted for this 

 volume has been given in a previous chapter (chapter 19, page 

 367) ; viz, that a soil must be considered calcareous so soon as 

 it naturally supports a calciphile flora the " lime vegetation " 

 so often referred to above and named in detail. Upon this 

 basis it has been seen that some (sandy) soils containing only 

 a little over one-tenth of one per cent, of lime show all the 

 characters and advantages of calcareous soils ; while in the case 

 of heavy clay soils, as has been shown, the lime-percentage 

 must rise to over one-half per cent, to produce native lime 

 growth. While in the United States observations of the con- 

 trasts between calciphile and calcifuge floras are easily made 

 in the field, and the facts must attract the attention of any 

 fairly qualified observer, in Europe they would have to be made 

 the subject of special cultural investigation based upon soil 

 analysis ; a procedure not yet fully accredited abroad, any more 

 than in the United States. In a general way it has however 

 been recognized by Msercker, as shown at the end of the pre- 

 ceding chapter. How far this estimate was based upon Ameri- 



