1916] FIELD CROPS. 335 



that continuous selection of either the yellow or the brown seeded forms failed 

 to establish pure transmission of the seed color. It was further found that 

 self-pollination of mustard can take place and that self-pollination continued 

 several generations does not reduce the yield of seed or give rise to weak plants. 

 Crossing a pure yellow-seeded form with a brown-seeded plant of one of the 

 lines studied indicated that xenia in the yellow-seeded mother plant may show 

 itself in the form of a browning of the seed coat. Such a cross also showed 

 a different behavior in the Fi and a different segregation in later generations 

 tlian the cross of pure yellow-seeded with pure brown-seeded mustard. 



Experiments were conducted with oats to determine whether individual 

 Johannsen lines may be permanently distinguishable from each other by means 

 of the hairs and awns of the outer or lower grains in the spikelets, the color 

 of the glumes of these grains, or the number of grains per spikelet, even when 

 selection in opposition to the line characters is practiced. After the constancy 

 of the line character had become apparent, a comparison of a number of 

 morphologically uniform lines was made to establish whether the relative 

 heritability of characters finds expression each year or only in the average 

 of several years. Finally, studies were made to determine whether seasonal 

 conditions had a definite influence on the characters under observation. The 

 work was begun with four plants grown from grains taken in 1906 from seed 

 of Sechsamt oats. 



The observations made on a series of external characters indicated without 

 exception that in a Johannsen line definitely directed selection, even if carried 

 through a comparatively large number of generations, does not modify the line 

 character. The different characters studied were the varying degree of de- 

 velopment of the highly modifiable coloring of the seed coat, the interchange 

 between two colors of the seed coat as exhibited in subvarieties of mustard, 

 and the variable development of the very strongly modifiable external characters 

 of hairiness, the presence of awns in the outer grains of oats, and the number 

 of grains produced per spikelet in oats. A number of cases of spontaneous 

 qualitative variation which appeared after a varying number of generations 

 had been self-pollinated are reported. 



From the results of the breeding investigations it was concluded that cer- 

 tain external characters, such as those mentioned above as having been the 

 subject of these studies, can not be brought, even by means of continued self- 

 pollination and selection, to a more definite, permanent, and stronger expres- 

 sion. It is stated that the Johannsen lines in question belong to form groups 

 which either show the several characters with different degrees of modifica- 

 tion or, as in the case of the mustard lines, represent subvarieties. The state- 

 ment is made that seed production in the field is more difficult when the par- 

 ticular form group has such highly variable external characters as some of the 

 Johannsen lines of legumes and oats here studied. It is believed that the value 

 of continuing selection with self-pollinated plants was further brought out by 

 the possibility of spontaneous qualitative variations as shown in these experi- 

 ments, as well as by the fact that certain branches of a Johannsen line may 

 exhibit a difference in growth for several years. Spontaneous quantitative va- 

 riations were not observed in any of the lines under experiment. 



[Work with field crops], A. Boss {Minnesota Sta. Rpt. 1915, pp. 35, 36). — 

 The activities of the sections of farm crops and of plant breeding are briefly 

 noted. 



Experiments with different grades of seed oats are reported as showing that 

 the heavier seed gave the larger increased return for the labor of preparation, 

 and that for certain varieties of oats thick seeding seemed to be an advantage. 



