No. 611] LINKED CHABACTERS IN WHEAT CROSSES 687 



they were opaque and graded insensibly into the condi- 

 tion of pure No. 35 it was considered impracticable to 

 make the arbitrary designation of degrees of hardness 

 any more complex than the three groups used. It should 

 be added, on the other hand, that a number of races were 

 secured which were as soft or softer than the type of No. 

 35 and a number of races which, to all appearances, were 

 ' fully as hard as pure No. 1. The inheritance of hardness 

 will, however, be reserved for discussion in a later paper. 



The question now arises as to whether this correlation 

 is genetic or physiological. Might it not be caused by the 

 simple fact that poorly filled (with starch) hard grains 

 will give rise to a more flattened head, than will plump 

 (starchy, soft) grains by failing to fill up and distend the 



