STRUCTURE OF THE BOLL 73 



assistance which they might provide to persons wishing 

 to ascertain the age or state of ripeness of odd samples of 

 cotton-seed or of seed cotton which might have to be 

 examined. An entomologist, for example, could easily 

 use them for dating the attack of a boll-worm. If used 

 for such purposes, however, it would be advisable to take 

 a check series when possible, as the times given would 

 necessarily vary to some extent from country to country, 

 and even within the same variety. Thus, at Giza, in 

 1913, while Strain No. 77 had a maturation period of 

 forty-eight days, the same period on the same land for 

 " Domains Afifi " was fifty-one days. 



DEVELOPMENT OF THE LINT (Fig. 11, C, and Fig. 13). 

 Whatever refinements we may ultimately be able to 

 introduce into our knowledge of lint development, so as 

 to explain the origin of subtle differences which only the 

 expert can detect, between samples of the same uni- 

 formity, length, breaking strain, diameter, and colour, it 

 is now clear that the progress of inquiry has been ham- 

 pered in the past by unnecessary and mystical elabora- 

 tions of what is actually a most simple story. 



The origination of the fibre is quite independent of 

 fertilization, and also of pollination. Flowers picked at 

 noon on the day of flowering show well-defined lint hairs, 

 about as long as they are broad (Fig. 11, 6', b). The 

 lint hair itself is a simple unicellular hair, formed by the 

 outward extension of the external wall of a single outer 

 epidermal cell of the outer seed-coat. The full diameter 

 of the hair is attained almost at once, when it is only 

 iV millimetre in length (Fig. 11, <7, c), while its length 



