76 



THE DEVELOPMENT OF RAW COTTON 



oxide) it causes the familiar beaded appearance, the cellulose 

 of the wall swelling through torn places in the cuticle. 



The actual length to which the hair attains depends in 

 the first place on the inherited nature of the plant which 

 bears it, as discussed in a former chapter, and in the 

 second place on the environmental circumstances during 

 some ten days only, as discussed in Chapter IV. What- 

 ever may have happened to the plant before or after 

 these ten days cannot affect the length, exclusive only 

 of the self- poisoning phenomena of Senescence. These 

 latter probably enter to some extent into the life-history 

 of every hair, but more research is needed upon them. 

 One obvious utility of such research should be apparent, 

 in that if senescence is the cause which checks the growth 

 of the fibre at a certain length, it might be possible to 

 obviate it, and produce lint of any length desired ! 



In the case of a batch of flowers marked on July 10, 

 1913, and picked at regular intervals till maturity, on 

 No. 77 strain, the final mean length attained by all the 

 fruits left to ripen was 30 millimetres (determined by 

 seed- combing). The flowers from a few days before and 

 after also gave the same length, so that the environmental 

 circumstances were obviously acting fairly uniformly at 

 the time. The mean length per day in the developing 

 bolls was as follows : 



^_- 



Day : | 3rd. \ 6th. , 9th. j 12th. ' 15th. 18th. 21st. 24th. ; Ripe. 



Length in milli- 

 metres 



6 11 16 ! 23 29 30 30 



