170 SYSTEMATIZED PLANT-BREEDING 



cannot be recognised with any approach to the 

 certainty with which it could be in the case first 

 investigated. This is due to the fact that even 

 English wheat may have all the appearance of a 

 strong wheat, though in the bakehouse it may be 

 impossible to make a presentable loaf from it. 

 One can control this appearance to a certain extent 

 by appropriate cultural conditions, but still the 

 fact remains that one has to work with character- 

 istics which one cannot readily identify. Under 

 these circumstances part of the produce of every 

 plant chosen for further propagation has to be 

 tested by the tedious chewing process or one has 

 to chance matters and trust that the F 3 or F 4 

 generation will reveal the characteristics with 

 greater certainty. The method, though satisfactory 

 in practice, is far from ideal, for it involves the use 

 of a considerable area of land and a great deal of 

 labour at harvest time when it can least be spared. 

 The next difficulty is to secure the combination of 

 strength and high yield in one and the same variety, 

 for the strong wheats we have to use as parents 

 for the time being cannot be said to be average 

 croppers except under particularly favourable con- 

 ditions. This combination is essential because 

 heaviness of crop outweighs every other considera- 

 tion with the English farmer, though in countries 

 such as Canada quality is the chief factor which 

 determines whether or not a variety is worth 

 cultivating. Unfortunately very little is known 



