cH.iii DEVELOPMENT AND ENVIRONMENT 55 



boll which does not ripen. We should also be able to 

 discuss the growth phenomena shown by the lint in the 

 boll, but the experimental difficulties of such investiga- 

 tion have not yet been overcome, and this section of the 

 development, which is of prime interest to the spinner, 

 must be left almost blank. 



Methods of observation. — So far as this part of 

 the research has at present been carried, the author has 

 had to devise methods in which the accuracy of the 

 individual observation is low, while the ultimate precision 

 of the result is due to multiplication of such observations. 

 Thus, averages are worked out for a large number of plants 

 and expressed in terms of " per plant per day" (abbreviated 

 for convenience to " p.p.p.d. "), with respect to such 

 characters as the opening of flowers, the ripening of bolls, 

 the shedding of flowers, and the growth rate. 



The results are usually plotted in graphic form for 

 convenience in examination. 



The lack of moderately trustworthy assistance in Egypt 

 often makes it necessary to arrange the time-table of work 

 so as to have daily observations on special plants and 

 groups for three days, then for three days more on another 

 series, and to take those families where the number of 

 plants is large, such as varieby-rows, only once a week, 

 depending on the greater number of component individuals 

 to compensate for the scarcity of observations. All these 

 observations can be plotted down to the same "p.p.p.d." 

 basis, and are directly comparable with the results obtained 

 by daily observation, or from large areas. 



Tiie task of working data up at any stage is lessened by 

 tabulating note-books at the beginning of the season, 

 though the balance between minimum discomfort in the 

 field, and facility at the writing-desk, is not always easy 

 to strike. The speed of desk- work can often be greatly 

 increased by preparing nomographs to take the place of 

 the slide-rule. 



