FIELD CROPS. 333 



vidual seeds, which differ according to the size, location on the stem, and degree 

 of ripeness of the seed bolls. 



As a means of securing more comparable results the author advises (1) that 

 the germinative ability of beet seeds be reckoned on weight rather than ou 

 number of seed bolls; (2) that the conditions of the test take a more liberal 

 form ; and (3) tliat in making the determinations of germinative ability a some- 

 what greater latitude be given. 



The inheritance of quantitative characters in maize, R. A. Emerson and 

 E. M. East {Nebraska Sta. Research Bui. 2, pp. 5-120, figs. 21). — This bulletin 

 discusses somewhat fully the inheritance of quantitative characters and pre- 

 sents data bearing upon this subject secured from experiments with maize 

 conducted by the authors working separately. The materials used were a strain 

 of Tom Thumb pop. Missouri dent, California pop. Black Mexican sweet, Wat- 

 son fiint, Leaming dent, Illinois low protein, Illinois high protein, Early Crosby, 

 Sturges flint, and Longfellow flint. 



It is noted that the results secured from the experiments were what might 

 well be expected if quantitative differences were due to numerous factors in- 

 herited in a strictly Mendelian manner. Real genetic correlations in the sense 

 of gametic associations are not antagonistic to the Mendelian doctrine. 



In a study of 8 different crosses the parents varied from 8 to 20 rows and 

 in nearly every case Fi was iutermediate between the parents, though in the 

 case of one cross of the 8-rowed variety with an apparently 12-rowed variety 

 the latter condition seemed to dominate. In most cases the Fj generations had 

 a wider range of variation than Fi, a range that included both par«it types. 

 The differences between the F2 families of a single cross are believed to have 

 been due to heterozygosis of one or other of the parent varieties. Where F» 

 families were grown the parent types were recovered in every case and inter- 

 mediate types were also seen. 



In the study of inheritance of length of ears, in each case the ear length of 

 one parent was approximately two and a half times that of the other parent. 

 In the cross of Tom Thumb with Black Mexican the Fi ear length was dis- 

 tinctly intermediate between the parental ear lengths. In the cross of Missouri 

 dent with California pop the Fi generation had ears practically as long as 

 those of the long-eared parent, but the extreme length of the Fi ears was doubt- 

 less in part due to heterozygosis, for the means of the Fj families were dis- 

 tinctly intermediate between the parental means. In every case the Fi frater- 

 nities were more variable than the Fi lots. 



The inheritance of diameter of ears was investigated in 2 crosses. The 

 ears of Fi were intermediate in diameter between those of the parents but some- 

 what nearer the larger-eared than the smaller-eared variety. The F2 ranges of 

 variation little more than filled the gap between the parent races. The parent 

 types were not recovered in Fa, but the several Fs lots were very distinct. The 

 smallest ears of the largest eared Fj families were larger than the largest ears 

 of the smallest eared families. 



Weights of seed were determined only for the cross Tom Thumb-Black Mexi- 

 can. It is noted that the seeds taken to represent the latter variety were 

 probably too large owing to previous mixture of strains. If allowance is made 

 for this the Fi seed weight was only a little below the mid-parental weight, and 

 the ranges of variation of the ¥2 fraternities well overlapped the ranges of the 

 parents. One F3 family had a seed weight nearly equal to that of Black Mexi- 

 can and the great variability of several Fs lots indicated heterozygosity suffi- 

 cient to enable the isolation of the pai'ent types on further selection. 



