12 MKLOX CULTURE 



The Function of Root Hairs. — The absorption of 

 plant food is accomplished by means of very fine 

 root hairs, which may be seen very nicely on melon 

 roots which have grown between folds of muslin 

 or thick paper. These root hairs play a very im- 

 portant part in the growth and development of the 

 plant, but they cannot perform their natural func- 

 tion in the absence of free air. This condition ex- 

 ists in soils that either contain an excess of moisture 

 or that have been worked while they were in this 

 condition, thereby causing them to bake. 



The ideal soil for this class of plants, therefore, 

 must contain enough plant food and water to fully 

 supply the plants and yet be so porous that the air 

 can circulate through it and come in contact with 

 the roots. Each particle of such a soil is surrounded 

 with a thin film of water, while between the parti- 

 cles are spaces connected with each other and filled 

 with moist air that is in communication with the 

 air above the soil. The root hairs apply themselves 

 intimately to the wet surfaces of the soil particles, 

 or extend themselves into cavities filled with sat- 

 urated air, and are thus able to draw in the well- 

 aerated soil water with its dissolved food constitu- 

 ents in sufficient quantities to restore the loss from 

 transpiration and to distend the newly formed cells. 



It must be remembered that the soil is Nature's 

 great chemical laboratory, in which many changes 

 are going on constantly ; by decomposition, the 

 countless million, of plants and animals are acted 

 upon by myriads of bacteria, whereby nitric acid, 

 which supplies the higher plants with their most 

 useful food element^ — nitrogen — is formed. The 

 carbonic acid which these plants took from the air 



