586 



Journal of Agricultural Research 



Vol. XIX, No. ir 



where this can be done readily, because the others, where the differences 

 in percentage of fertility occur, are heterozygous for one or both main 

 factors. If there is a third factor, the Fj generation indicates that it 

 is expressed here as a i to 3 ratio with the heterozygous forms indis- 

 tinguishable from those homozygous for the absence of the factor. 

 By the same reasoning, lines 10 and 95 in Table I, which showed fer- 

 tility, should be homozygous for the presence of the factor and should 

 exhibit a higher percentage of fertility than the progeny of the other 

 five lines. The F3 progeny of lines 10 and 95 averaged 54.6 and 48.4 

 per cent of fertility in the lateral florets, while the progeny of the other 

 lines v/ere, respectively, 35.7, 33.2, 30.3, 25, and 17.8 per cent fertile. 



The data indicating a third factor in fertility are summarized in 

 Table III. The evidence at hand is not more than an indication of a 

 minor factor, yet the material itself is far more suggestive of such a 

 factor than the evidence. 



Table III. 



-Summary of data indicating a third factor of fertility in the cross between 

 Manchuria and Svanhals 



DISCUSSION OF RESULTS 



FIXED INTERMEDIATE, H. INTERMEDIUM 



Since tne purpose of this study was to gain a better understanding of 

 the occurrence of H. intermedium, this form is of greater interest here 

 than any of the other segregates. From the standpoint of historical and 

 present interest there are three questions which can now be answered. 

 There is no doubt that such forms occur; they have been found to be 

 stable; and in the particular cross reported here in detail the ratio of 

 appearance is approximately i to 16. 



The stability of this form was established by obser^'^ations on interme- 

 diates obtained from several crosses. The field experiences fit in well 



