48 ROOT-HAIRS. [CH III 



be remembered that the water so absorbed is the vehicle 

 by which the plant receives two-thirds of its food material, 



FIQ. 20. 

 A SEEDLING WHEAT WITH SOIL ADHERING TO THE ROOTS. (After Sachs.) 



for it is in this way that nitrogen in the form of nitrates, 

 sulphur in the form of sulphates, phosphorus as phosphates, 

 calcium, potassium, magnesium and iron reach it. To this 

 part of the subject I shall return. 



