ON A CASE OF PERMANENT VARIATION IN THE 

 GLUME LENGTHS OF EXTRACTED PARENTAL 

 TYPES AND THE INHERITANCE OF PURPLE 

 COLOUR IN THE CROSS TRITICUM POLONI- 

 CUM X T. ELOBONL 



By A. St CLAIR CAPORN. 



(With Plates XIII and XIV, three charts, and one text-figure.) 



T^E work set forth in this paper was initiated by Professor Biffen, 

 who made the cross in 1913 and carried it on to the F2 generation. 

 Thereafter, from the analysis of the F^ figures, the experiment has 

 been in the hands of the writer. Rust, together with weakness of 

 straw, was often responsible for considerable damage, lowering and 

 shrivelling the grain output per plant, and thus increasing the difficulty 

 of discovering faint colour traces usually borne on only a few of the 

 riper grains. 



The Polonicum Parent. 



Triticuni polonicum is a tallish wheat about 4 — 4^ feet high. The 

 tillering is poor, most of the plants having only two stems which difi*er 

 from ordinary straws in being solid. The species is moderately sus- 

 ceptible to rust. 



The ear is very long, lax, and bearded. Owing to their great length 

 the outer glumes are a characteristic feature. Practically smooth, flat, 

 and deeply keeled, they spread out stiffly at flowering time, giving to 

 the ear the appearance of having been rubbed from the tip downwards. 

 (Plate XIII, figs. 1 and 2.) 



Average glume length (82 ears) = 29'23 mms. 



The frequency distribution is shown in Chart I. 



