STRUCTURE OF THE BOLL 59 



the flower-bud (PL VIII.). This new bud grows out in 

 almost a straight continuation of the old stem, forcing 

 the flower-bud and its stalk sideways, and itself repeats 

 the same performance. Each new flower is therefore in 

 reality a lateral branch from its predecessor, though the 

 general appearance is as if each flower was an offshoot 

 from a main flowering branch. 



The flower proper begins to develop inside the three 

 enclosing bracts at a date which can be fixed with cer- 

 tainty as being twenty -three days before the flower opens, 

 in the case of No. 77 strain grown at Giza. 



During these twenty-three days the various portions 

 of the flower are developed, and their internal structure 

 is differentiated. 



The chief of these latter processes is the formation of the 

 male and female sex-cells; but as the author has dealt with 

 them fully elsewhere, and as the details are not immediately 

 relevant to our present topic, a few general remarks will 

 suffice. 



The various parts of the open flower are the green ring of 

 the calyx (which must not be confused with the three external 

 leafy bracts), the coloured petals, the hollow brush of stamens 

 containing the pollen, and the ovary containing the ovules. 

 The latter develops after flowering and fertilization into the 

 fruit, or boll, and into the seeds, respectively. 



The pollen-grains each contain two male nuclei and one 

 other nucleus. The nucleus is a definite structure found in 

 the protoplasm of every living cell (e.g., Fig. 11, B, b, and C, c), 

 there being usually one nucleus to each of the cells which by 

 their growth and multiplication build up the bodies of all 

 living organisms. The function of this nucleus appears to be 

 that of directing and controlling the behaviour of itself and 

 of the rest of the living substance, or protoplasm, of the cell. 



