368 



HOW CKOPS-GROW. 



contact with its particles. This contact is much more 

 intimate than has been usually supposed. If we care- 

 fully lift a young wheat-plant from dry earth, we notice 

 that each rootlet is coated with an envelope of soil. This 

 adheres with considerable tenacity, so that gentle shak- 

 ing fails to displace it, and if it be mostly remoyed by 



Fig. 43. 

 vigorous agitation or washing, the root-hairs are either 

 found to be broken, or in many places inseparably at- 

 tached to the particles of earth. 

 Fig. 40 exhibits the appearance of a young wheat- 



