ACQUISITION OF NUTRIENTS BY PLANTS 287 



maize, oats and wheat may be increased by increasing 

 the ratio of nitrogen to other nutritive substances in 

 the nutrient media. This is also true of potassium and 

 phosphorus, respectively. This fact is accounted for 

 by the maintenance of the osmotic equilibrium at a 

 higher level for a particular ion which is relatively 



Fig. 99. Showing the intimate relation of root-hairs and soil particles. 



abundant in the nutrient solution, thus preventing the 

 return of the excess from the plant. 



148. Relation between root-hairs and soil-particles. 

 In a rich, moist soil the number of root-hairs is very 

 great, while in a poor or a dry soil there are compara- 

 tively few. The connection between the root-hairs and 

 the soil-particles is extremely intimate. When in con- 

 tact with the particle of soil, the root-hair frequently 

 almost incloses it, and by means of its mucilaginous 



