158 MEXDELISM chap. 



Taken as a whole English wheats compare favourably 

 with foreign ones in respect of their cropping power. On 

 the other hand, they have two serious defects. They are 

 liable to suffer from the attacks of the fungus which causes 

 rust, and they do not bake into a good loaf. This last 

 property depends upon the amount of gluten present, and 

 it is the greater proportion of this which gives to the 

 '"hard" foreign wheat its quality of causing the loaf to 

 rise well when baked. For some time it was held that 

 '"hard'' wheat with a high glutinous content could not 

 be grown in the English climate, and undoubtedly most of 

 the hard varieties imported for trial deteriorated greatly 

 in a very short time. Professor Biff en managed to obtain 

 a hard wheat which kept its qualities when grown in 

 England. But in spite of the superior quality of its 

 grain from the baker's point of view its cropping capacity 

 was too low for it to be grown profitably in competition 

 with English wheats. Like the latter, it was also subject 

 to rust. Among the many varieties which Professor Bif- 

 fen collected and grew for observation he managed to find 

 one which was completely immune to the attacks of the 

 rust fungus, though in other respects it had no desirable 

 quality to recommend it. Now as the result of an elab- 

 orate series of investigations he was able to show that the 

 qualities of heavy cropping capacity, "hardness" of grain, 

 and immunity to rust can all be expressed in terms of 

 Mendelian factors. Having once analysed his material 



