F. L. Engledow 103 



In the 2-bis-6 class were found several types, such as "Spitz," "Spitz 

 verlangert," etc., and consequently, although he recognised that the F2 

 ratios were monohybrid, he thought it desirable to employ a di-hybrid 

 or 2- factor explanation, because of the diversity of the heterozygote 

 forms. The fit of observation to expectation is good. As factors were 

 employed : Z, which is responsible for the 2-row state ; W, an intensifier 

 which is operative only in the presence of Z, and in the absence of 

 which there is an " tjbergehen " from 2-row to 2-6-row. In the light 

 of the evidence furnished by the crosses described in this paper, two 

 points of V. Ubisch's theory appear not to harmonise with the facts of 

 observation. These are : 



(a) Plants of the constitution ZZWw and ZZww are described as 

 2 bis 2-6 zeilig. This seems to imply that 2-zeilig is not genetically a 

 definite group. The evidence of Table II demands that it should be of 

 definite and invariable genetic constitution. 



{^) The ratio 6-row : all others is stated to be 1 : 3. In Table II 

 the ratio 2-row : all others also appears to be 1 : 3. v. Ubisch however 

 finds that the proportion of 2-row : all others is 3 : 13. This divergence 

 fi-om the results recorded in Table II is, of course, simply a consequence 

 of (a) above. 



IV. The Problem of Inheritance in Lateral Florets. 



As described in § II, the lateral florets found in the various races of 

 barley, and in their crosses, form a series (A) — (G). There is reason to 

 believe that (B), (C), (D) and (E) are genetically alike in regard to 

 constitution for the development of reproductive organs. Probably 

 there occurs a further series, corresponding to (B), (C), (D) and (E), 

 and produced by crosses between decipiens and distichum types (see 

 below). 



The evidence which has accumulated up to date concerning the 

 general question of lateral floret inheritance in barleys seems sufficient 

 to justify a brief review. Much of it has already been published by 

 Biffen (4) and (5). In these publications will be found the details of 

 those cases which are simply recorded in outline below. The four sub- 

 groups of barley — hexastichum, intermedium, distichum, decipiens — 

 together with the interesting awnless H. inerme, permit of ten sets of 

 crosses, and these are now described serially : 



(a) Hexastichum x intermedium, i.e. (A) x (B). 



In all cases the F^ had six complete rows of fertile florets, but the 



