38 THE DEVELOPMENT OF HAW COTTON 



feet than from any other part, so that a boring -tool may 



be pushed through wet mud on the surface and broken 



Deep ky attempting to struggle through the hard 



Draught of dry soil at that depth (Fig. 17). Many other 



the Eoot. side-issues show the enormous possible ex- 

 tent of the cotton root system. Thus, a plant which is 

 allotted 3 square metres of surface will produce more 

 flowers and more cotton than a plant which receives 

 2 square metres allowance. Since the root of the latter 

 has about five tons of soil to itself, it might be considered 

 to receive ample accommodation; but the plant can still 

 make use of more. The last fact brings up in vivid relief 

 the artificial conditions of field-crop cultivation, where 

 the plants are crowded together (Fig. 5, PI. XII.) to such a 

 density as will produce the maximum yield, and the con- 

 sequent limitations in the size of the root system have to 

 be met as far as is possible by skill in cultivation. The 

 author is sometimes inclined to think that in irrigated 

 countries with high-priced cottons the tendency will be 

 towards even closer crowding of the plants, as skill in 

 cultivation becomes greater through better understanding 

 of their necessities. Certainly the heavy first picking 

 which results from closer spacing should be a valuable 

 asset (if skilfully ripened off) in countries troubled by 

 boll- worms, which attack the later pickings. 



The last component of the soil question is the chemical 

 composition, and here Egyptian experience is not of much 

 Use, since manurial composition is rarely the principal 

 limiting factor of growth there, though there is some 

 indication that it acts as such for short periods at certain 



