98 THE COTTON PLANT IN EGYPT chap. 



to the nearest millimetre exept in the filaments, where 

 half-millimetres are attempted. Three flowers are 

 examined on every plant, and the means for all three are 

 taken. 



First flower and maturation. — The obvious effect 

 of early stunting is to provide a long tail of late-flowering 

 plants upon a graph which shows the date of the first 

 flower. If the originally stunted plants are excluded, the 

 P.E. of this date works out at a little more than four 

 days in most families, or 3^ per cent, of the time elapsing 

 between sowing and flowering. 



The maturation of the flowers opening during early 

 July at Cairo has been directly recorded by marking the 

 flowers. The results for, e.g., family " 77 " in 1911 gave a 

 mean of forty-eight days with a P.E. of ± 3'0 per cent. 

 The period is longer in the Delta. 



Flowering and boiling. — The limits of the present 

 volume do not permit of detailed discussion of the 

 fluctuation from plant to plant in flowering- and boiling- 

 curves, beyond the account of the possible controlling 

 factors already given. 



The influence of sowing-distance is shown in Fig. 44, 

 four times the number of flowers being found on wide- 

 sown plants as against field sowing. The point is important 

 with regard to propagation of new varieties ; ^^ by wide- 

 sowing we can obtain 100 bolls per plant from a strain 

 which will only produce 15 to 20 in field crop. 



The influence of defoliation by cotton-worm is peculiar, 

 the flowering being immediately arrested, but subsequently 

 extended much later than usual, so that a warm autumn 

 may enable the ultimate yield to reach the normal. 



A few points of interest arise with regard to the total 

 production of flowers up to a certain date, and the bolls 

 developed from them. The correlation between these two 

 quantities was worked out in the wide-sown, very irregular 

 family of " 17" for 1910, with the following results. 



