ENVIRONMENT OF THE BOLL 119 



becomes a limiting factor, and barring accidents such as 

 boll-worms and water-tables, let us see where the longest 

 Differences anc ^ strongest lint was produced in this 

 between Daily Picking Series. The lengths of the 

 Pickings, earliest bolls have not been determined, but 

 their weakness puts most of them out of the running; 

 those of September 3 were good in both respects, but 

 only slightly superior to those of September 26, and on 

 October 9 we have another period which is much the 

 same. An important conclusion follows from this search 

 for good samples: it should have been possible so to 

 adjust the irrigation intervals that the length and strength 

 of the samples, although determined at 23-day intervals, 

 should move together. The obvious way of doing this is 

 to keep the intervals between irrigations constantly re- 

 lated to 23 days for this strain, and to 20-26 days for 

 other strains and sites. 



It may not be entirely coincidence or convenience, as 



is commonly assumed, that the rotation of water in the 



Egyptian canals is commonly arranged 



nearly at this interval; the usual explana- 

 Rotations. 



tion is that the cotton cannot stand longer 



intervals without water, but this is not strictly correct. 

 Personally the author considers that lighter waterings at 

 11 and 12 day intervals alternately would be tetter still, 

 and would of course produce the same result. 



Leaving this point, and assuming that the irrigation 

 intervals had been so adjusted as to change length and 

 strength simultaneously, this would not abolish the net 

 change of both. Thus the commercial pickings would 



