DISTINCTIONS IN CULTIVATED BARLEYS. 6 



casin, Mont.; Aberdeen and Gooding, Idaho; and Chico, Cal. Of 

 the work done at these points, that at St. Paul, Minn., which was 

 conducted in cooperation with the State experiment station, was the 

 most extensive. 



REVIEW OF THE LITERATURE. 



Although the literature of barley is, with the possible exception 

 of wheat, more extensive than that of any other cereal crop, the pub- 

 lications bearing directly upon the theme of this paper are com- 

 paratively few. The great mass of the European publications, 

 especially the German ones, have to do Avith the malting quality of 

 barley. They are concerned mostly with its chemical constituents, 

 the effect of soil, climate, and culture upon the nature and composi- 

 tion of the grain, and the behavior of the converting enzyms in 

 grains of different character. The same is true of papers on the 

 morphology of the grain, and even many of the publications treating 

 directly of barley breeding have little bearing upon the present dis- 

 cussion, as they are often concerned only with the correlation of 

 characters or with the behavior of hybrids. It is only the papers 

 dealing with the taxonomic features of barley, and experiments such 

 as those of the Swedish Plant-Breeding Association at Svalof, 

 which have had for their end the isolation of plant variants, that are 

 of particular pertinence. 



The first comprehensive systematic work was that of Kornicke 

 (15) % who described 44 botanical forms of barley, using spikelet 

 fertility, color, nature of the awn and glume, and the adherence or 

 nonadherence of the palea. His groups will undoubtedly form the 

 bases of all future classifications. The classification of Yoss (25) is 

 important largely because he based a part of it upon the extent of 

 overlapping of the grains, thus forecasting in an indefinite way the 

 use of density. Atterberg (2) made use of the bristle and nerve 

 characters discovered by Neergaard, mentioned below, and subdi- 

 vided the previous groups until he had 188 named botanical varieties. 

 Beaven (3), by a rearrangement and compilation of previous classi- 

 fications and by growing and describing a large number of hybrids 

 of Karl Hansen, Kornicke, and others, gave a very clear conception 

 of the entire species. His work is perhaps most valuable in the 

 placing of the Abyssinian forms with abortive lateral florets in a 

 group by themselves. He does not make use of the finer subdivisions 

 employed by Atterberg. Eegel (21) , on the contrary, carries the sub- 

 division still farther and uses twisting of the spike and earliness and 

 lateness of the variety in his separations. The last, a purely physio- 

 logical phase, he employs in named botanical forms. 



A review of the work at Svalof is especially valuable in this con- 

 nection because of the fact that a large part of that effort has been 



*The figures in parentheses refer to the bibliography at the end of the bulletin. 



