180 THE COTTON PLANT IN EGYPT CH. x 



his personal freedom than any other manifestation of the 

 " march of progress." 



With regard to the general cultivation of cotton, 

 these researches have thrown into prominence the 

 immense importance of the root system, whereof in a 

 limited sense the aerial portions are only the visible 

 expression. 7 ' 13 ' 15 ' 16 ' 26 ' 27 ' 29 It seems probable that a great 

 deal of botanical research in the coming twenty years will 

 be subterranean. Researches have also cleared .up the 

 causes of seed-failure, have obtained some general ex- 

 pressions for the effect of environment on development, 

 and by means of a system of records, which can be kept 

 with no more trouble than meteorologists' observations, 

 they have thrown light on the causes of variation in crops 

 from year to year, and from place to place, in the form 

 of certain curves of flowering, boiling, and growth, which 

 have a precise value. 



The designation of lines upon which to drive our wedges 

 still further into the mass of available material is almost 

 impossible, since the most valuable results are usually 

 obtained by following out a side line, which in its turn has 

 been detected through the accidental direction of attention 

 to a commonplace phenomenon. Knowledge of the 

 changes in water-content of various layers of soil can be 

 applied directly to irrigation practice, study of the growth 

 processes in the fruit will demonstrate the causes of 

 fluctuation in the grade of the commercial product, and 

 any information about the infectivity of foreign pollen 

 may reveal the way by which the contamination of 

 varieties can be eliminated. Lastly, it should be borne in 

 mind that most of these researches are based on evidence 

 collected at the apex of the Egyptian Delta, so that there 

 is a long field of operations in which our present results 

 may be re-examined, stretching from the Mediterranean 

 into the heart of the Sudan. 



