174 THE DEVELOPMENT OF RAW COTTON 



thus obtained were marked on the boiling curve, when it 

 was found that each date was three days later than a 

 sudden rise in the boiling, which we knew to be due to 

 diminished shedding; this marked the interval between 

 the opening of the flower and the opening of the 

 boll as 51-3 (or 48) days for strain No. 77 in 1913, 

 repeating the conclusion formed by direct determination 

 in 1910. A system of records obtained at very little 

 personal trouble or official cost, which will thus cast up 

 evidence at will, splitting apart differences of three days in 

 a period of seven weeks, is obviously not without its uses. 



Such an example also shows the precision to which 

 field crop botany might be developed. 



A fuller account has been given elsewhere of the 

 methods by which these records were obtained, and only 

 sufficient has been said here to explain the nature and 

 purpose of them, and to make the appearance of the 

 plant-graphs in the figures intelligible. 



Cytological Methods. The earlier part of this work was 

 effected in 1905 and 1906, when technical difficulties and 

 the absence of physiological data made it plain that no 

 further real advance was possible until more had been 

 found out concerning the physiology of Egyptian cotton. 

 The indirect attack, or flanking movement, took years to 

 develop, but in 1912 enough was known to justify a 

 resumption of the direct cytological investigation, and 

 material was collected which cleared up the whole story 

 provisionally in about a week at the microscope, and was 

 completely confirmed by the parallel and subsequent 

 studies of cotton ripened from dated flowers and bolls. 



