Sept.i.i92o Fixed Intermediate, Hordeum intermedium haxtoni 577 



siderable number of these were between 2-rowed and 6-rowed parents. 

 In 1 910 the Fi generation was grown, and in 191 1 the Fj generation. In 

 the Fj generation of 1910 the heterozygous intermediate was very vig- 

 orous, and a considerable number of selections were grown in 191 1 from 

 the small lateral kernels to see if they would produce vigorous plants. 

 In the F2 generation it was apparent that there were intermediates pres- 

 ent which differed from those of 1910, and 56 selections of different types 

 of intermediates were grown in 191 2. These came from 12 different 

 crosses and included the progeny of combinations of 10 different 2-rowed 

 and 7 different 6-rowed parents. A number of these proved to be homo- 

 zygous, and others were isolated from the F3 generation by further selec- 

 tion. Unfortunately, the records of 191 2 are incomplete, and the total 

 number of homozygotes obtained can not be determined. It is also 

 impossible to establish the complete list of crosses from which fixed in- 

 termediates were obtained. Beyond all question, from one to five fixed 

 intermediates were obtained from each of five different crosses. These 

 crosses involve three different 2-rowed and five different 6-rowed parents. 

 In these cases original material or complete records of the progeny are 

 still at hand. The crosses were as follows : S. P. I. No. 20375 X Svanhals, 

 Surprise X Primus, Primus X (2-rowed X 6-rowed), Garton 2-rowed X 

 Sex-radigt, and Manchuria X Svanhals. There is a definite statement 

 in the field records that a selection of zeocriton X Manchuria and another 

 of Chevalier X South African were fixed intermediates, but there are 

 neither specimens nor progeny records to confirm these statements. 



It will be seen that in the five crosses where the evidence is complete 

 the 2-rowed parents were dense-spiked. Aside from the fact that those 

 which have been preserved came from such crosses, there is no evidence 

 in the data now at hand that indicates inability to secure intermediates 

 from crosses in which both parents are lax-spiked. The common varie- 

 ties of lax 2-rowed barleys have less vigorous lateral florets than the 

 common varieties of dense 2-rowed barleys. It is possible that the prog- 

 eny of crosses where the lax forms were used would be lower in fertility 

 and the intermediates correspondingly less conspicuous. Hence, they 

 would be less desirable and less likely to be retained as specimens. 



In 1 91 5, after the junior author became connected with the Minnesota 

 Agricultural Experiment Station, it was decided to repeat one of the 

 crosses from which fixed intermediates had been secured, in order to 

 determine the inheritance and, if possible, to discover an explanation 

 of the occurrence of this form. By making crosses and growing an 

 occasional generation in the greenhouse in Washington in the winter and 

 sowing the seed in Minnesota in the spring several generations have 

 been studied since that date. The cross chosen for this purpose was 

 Manchuria X Svanhals. The F2 and F3 generations are reported in de- 

 tail. Other crosses were studied in which no intermediates were pro- 

 duced; but since the data are negative, they have not been included, 



