ENVIRONMENT OF THE BOLL 93 



This influence of soil -water is characteristic of the 

 Egyptian crop during the ripening of the bolls. In the 

 middle of June the climatic control, which has until then 

 been the main factor of the environment (acting chiefly 

 through night temperature, as we have formerly men- 

 tioned), is rapidly lost, with the increasing size and 

 evaporation of the plants, and thenceforward the chief need 

 is the maintenance of sufficient moisture around the roots. 



If we now examine the curves showing the changes in 



these various characteristics, such as lint length and 



Alterations strength, from one five-day mean to the 



from Day to next, the first feature which catches our 



Da 5 r - attention is the suddenness with which the 



changes take place. The length of the lint rises steadily 

 from 29-1 millimetres on August 1 to 30-9 millimetres on 

 August 10, or nearly T L inch in ten days; and this does 

 not give the full magnitude of the change, since the 

 calculation of five-day means tends to smooth out these 

 differences. The true change between July 29 and 

 August 12 is nearly 4 millimetres, or J inch, which in itself 

 is sufficient to change the commercial classification of the 

 lint produced. 



These sudden changes are shown by all the observed 

 characters, and it should at once be obvious that, when 



Average we s P ea k f tne properties of a bale of lint 

 Properties of ginned from the field crop of even a pure 



a Bale. strain of cotton much less from a com- 

 mercial variety we are speaking in averages. That the 

 pickings from different parts of the same field may be 

 different has long been recognized, as also the fact that 



