F. L. Englbdow 



95 



able fluctuation, and consequently inheritance results are recorded for 

 hairs (or bristles) only. 



In all cases observation was confined to the median florets, for these 

 florets alone exhibit well-developed rachillae throughout all the different 

 botanical classes of the barleys. The rachilla of the lateral floret reaches 

 a stage of development which corresponds very closely with the general 

 development of the floret itself Thus in H. hexastichum the rachilla of 

 the lateral is as well developed as that of the median. The "inter- 

 medium " barleys {H. Haxtoni and H. transiens) have full " bristly " 

 rachillae on their medians, while the rachillae of the laterals are long 

 and slender in the axis, the bristles being short and fine. In the 

 " distichum " barleys the laterals are small and infertile, and, whether 

 the rachillae of the medians be bristly or smooth, those of the laterals 

 have hairs which are so diminutive that they are scarcely visible even 

 under the microscope. Finally, in the "decipiens " barleys the lateral 

 floret is reduced to two very small empty paleae and no trace of rachilla 

 is to be seen. 



Certain varieties of barley show very great fluctuation in the form 

 of rachilla. In Praecox {H. hexastichum) in particular, a certain pro- 

 portion of abnormal rachillae is always found. It not infrequently 

 happens that only one rachilla on the whole ear is abnormal. Fig. 2 {a), 

 (b), (c), (d), (e), (/) illustrates commonly occurring abnormal types in this 

 variety. The normal type is the "bristly" (see (a) in Fig. 1). 



Fig. 2. 



Some of the abnormalities present a " leaf-like " form and in the F^ 

 of a Praecox x Archer cross there occurred the type shown in Fig. 3, 



7—2 



