The Orchard Plant 55 



are exceedingly delicate and are of short duration. As the 

 root increases in length, new ones are formed and the older 

 ones die, so that they are continually dying and new ones 

 are being formed throughout the growing season. (See 

 Fig. 5.) Great numbers of these organs are formed in good 

 soil which is in proper tilth, and thus provide the tree with 

 an immense absorptive surface. These 



".y* ' ' ^ * ' '-"Tr-"' 



tiny growths penetrate in between and |_ 

 often grow around the soil particles in i /""* 



order to absorb more readily the film of 

 water which surrounds the particles. 



Such delicate structures as root-hairs 

 are easily destroyed, so it is not to be won- 

 dered at that nursery trees, as they are re- 

 ceived by the orchardist, have lost all of 

 these organs. When such trees start into 

 growth, they do so at the expense of the 

 food that has been stored in the tissues, U 



and this drain must continue until new FIG. 5. A Root- 

 root-hairs can be f?rmed. Untoward con- 

 ditions of any kind, such as extremes of 

 moisture or drought, heat or cold, may cause the death 

 of these important organs. Hard, compact soils ex- 

 clude the air to such an extent that but few root-hairs 

 develop. Yellow foliage and a stunted growth are com- 

 mon sjTnptoms resulting from these conditions. 



The soil water, of course, contains small amounts of 



plant-food materials in solution; usually not more than 



.01 to .03 per cent of solid matter dissolved in it. 1 When 



the soil solutions contain as much as 2 per cent of dissolved 



1 Percival, "Agricultural Botany," p. 203. 



