18 . THE ROYAL SOCIETY OF CANADA 



Cross No. 908 



The second cross made was between the Arlington barley and 

 578D, the latter being a two-row, hooded sort. The plants of the 

 first generation were essentially uniform. No. 908 (plate A) is one 

 of these. This type was at first described as six-row, although the 

 two-row condition is supposed to be dominant. As a matter of fact 

 these heads are almost perfectly six-row in type; the median rows 

 being, of course, entirely filled, and the lateral rows showing only a 

 few gaps, chiefly at the base. These heads are certainly far more of 

 the six-row than of the two-row type. The median rows carry 

 rudimentary hoods while the lateral rows are without any trace of 

 hoods. In subsequent generations the heads of this heterozygous 

 type showed marked variations in the number of kernels developed 

 in the lateral rows, and in the degree of development of the hoods 

 on the median rows. Sometimes the number of kernels in the lateral 

 rows varied considerably in different heads from the same plant. 



When seeds from No. 908 (and others of the same pedigree) were 

 sown, four main types were produced (see plates C and D). 



Type I, two-row, with no awns, but with two rows of hoods. 



Type II, six-row or approximately six-row, with no awns, but 

 with hoods (usually very poorly developed) on the two median rows 

 only. The lateral rows often lack two or three kernels, and occasion- 

 ally more. 



Type III, two-row, with well developed awns on the median 

 rows. Occasionally a few kernels are present in the lateral rows. 



Type IV, Arlington type (or similar to Arlington), six-row, with 

 poorly developed awns on the median rows, the lateral rows being 

 strictly or nearly awnless. As in the case of type II, two or three 

 kernels are often wanting in the lateral rows, and sometimes the 

 number of gaps is greater. 



When the progeny of cross No. 908 and others of the same 

 parentage were being studied most of the plants seemed to belong, 

 definitely, to one or other of the four groups just mentioned. There 

 were a few, however, which quite defied classification. But, when 

 studied numerically, the grouping adopted proved inadequate to 

 explain the proportions of each type found, there being far more six- 

 row plants present (types II and IV) than were to be expected. 

 The number of plants belonging to each type was counted as accurately 



