94 



Inheritance in Barley 



I. The Rachilla. 



In the barleys two forms of rachilla are recognised. The first [(a) 

 in Fig. 1] has long, stiff, pointed hairs which are inclined to the axis of 

 the rachilla at a small but variable angle. The appearance of such a 

 rachilla is suggestive of a diminutive ear of barley, the rachilla hairs 

 corresponding to the awns of the ear. 



The second 'type of rachilla [(6) in Fig. 1] has a longer and more 

 cylindrical axis, and the hairs upon this axis are all short, fine, slightly 

 curled, and woolly in appearance. Commonly this type is known as the 

 " smooth " rachilla, the first type being called the "bristly " rachilla. 



{a) 



Fig. 1. 



Atterberg (1) uses rachilla character in his classification of the Barleys 

 to separate the " distichum " group into sub-groups, and in connection 

 with it he further employs a somewhat obscure and variable character, 

 viz. the prickles or projections on the nerves or veins of the outer palea 

 [the " zahnchen " of Komicke (2)]. In the experimental results here 

 recorded, these "projections" do not appear as a "character," for their 

 variability renders sorting unreliable. 



At first both the hairs (or bristles) and the axis of the rachilla were 

 noted in all the F^ and F>t plants, but it became apparent that in certain 

 cases referred to later the axis was liable to considerable and unaccount- 



