ENVIRONMENT OF THE BOLL 105 



of a whole crop, the order of variability is reversed, short- 

 period accidents tending to obliterate themselves ; so that 

 while ginning out-turn only changes by 1 or 2 per cent, 

 from year to year, length may vary more, and strength 

 so much as to mark off certain years of the Egyptian 

 crop, just like famous or infamous vintages of port and 

 champagne. 



Before considering the grader's report on the samples 

 from these dated flowers, it is necessary to deal with a 

 Weight of resu ^ derived mainly from other material 

 Single Lint than the series under discussion namely, 

 Hairs. the weights of single fibres. As in the case 

 of breaking strain, although the measurements of this 

 characteristic are not of direct use to the commercial 

 growers or users of cotton as they stand, it is quite pos- 

 sible that some simple indirect or mechanical method of 

 obtaining the measurements may be devised, and know- 

 ledge of them be turned to utilitarian account. The four 

 components which could affect the weight of a lint hair 

 are its length, the thickness of its wall, the density of the 

 cellulose of which the wall is composed, its diameter, and 

 its moisture-content. Length can be eliminated by- 

 cut ting uniform lengths out of the middle of a fibre, and 

 moisture by standardizing the humidity of the air in 

 which the weighings are made, or by calculation; we do 

 not know whether variations in the density of the wall 

 exist, but if such is the case they could be detected by 

 weighing hairs of equal thickness. In general, however, 

 the weight of the hair will depend on its diameter and 

 the thickness of its wall; thus the weights of fibres of 



