8 THE BIOLOGY OF FLOWERING PLANTS 



TABLE I 

 Composition of Soil Solution 



The differences exhibited by similar soils of different 

 fertility are illustrated by Table II : 



TABLE II 

 Composition of Soil Solution 



Sassafras Loam, New Jersey : centrifulgal extraction. 



It will be noted that the total concentration of the 

 solutes estimated ranges from 58 to 155 parts per million, 

 or from o"oo6 to 0*015 V^^ cent. The whole of the solutes 

 are not, however, included in these analyses. A complete 

 analysis of the drainage from unmanured agricultural land 

 at Rothamstead quoted by Russell shows about 250 parts 

 per million or 0*025 P^^' cent, of dissolved solids ; a manured 

 soil gave 0*04 per cent. 



Bouyoucos and McCool (19 15), who devised the freezing- 

 point method, find a depression in dry soils of round 

 about 1° C. ; this is equivalent to that given by a i"j per 

 cent, solution of salt. In moist soils the depression is much 

 less — round about 0*05° C, equivalent to that given by a 

 o"i per cent, salt solution. This is a concentration of the 



