’ 
1911] CURRENT LITERATURE 483 
while twenty corresponding F, families had an average height of 23.42 dm. 
and gave a yield of only 44.62 bushels per acre. 
Hayes and East have also shown a similar relation between first and 
second generation crosses, one such cross giving 105.5 bushels per acre in F, 
and only 51.5 bushels in F,, another cross giving respectively 117.5 bushels 
per acre and 98.4 bushels per acre. These authors give a good discussion of 
the economic bearings of these results and methods of putting them to practical 
‘Cotzmss has also shown the practical value of hybridization methods in 
corn growing, reporting on the results of sixteen rather wide crosses, all but two 
of which gave higher yields than the average of the parents, and all but four 
exceeding the better parent in yielding capacity. PEARL and SURFACE,™ 
while subscribing to the correctness of the genotype idea as applied to 7 
are of the opinion that the ordinary ear-to-the-row selection method “in a 
much cruder and less precise way, really makes use of the same chia 
the reviewer's “‘pure-line method,” and they wider simply the relaxation re) 
genotypes will have been satoinaticalty eliminated.” This view fails to t 
account of the relatively greater vigor in the F, hybrids. East, Hayes and 
East, and CoLins,” on the other hand, urge the use of the method of 
Morrow and Garpner,* as the most practical means of utilizing the greater 
vigor produced by heterozygosis, and the reviewer believes that the attitude 
of these authors is justifiable. The method of Morrow and GARDNER is 
identical with the “pure-line” method, except that highly developed commer- 
cial varieties are used in the place of pure self-fertilized strains. The two 
chosen parental types are grown in alternate rows in an isolated plot, and one 
variety is detasseled. The seed for the general crop is harvested from the 
detasseled row, and the process is repeated year after year, using the same 
parental varieties 
East and Haves” have made a most important contribution to knowledge 
™ Hayes, H. K., and East, E. M., Improvement in corn. Bull. Conn. Agr. 
Exp. Sta. pp. 21. pls. 4. 191t. 
3 Cottins, G. N., The value of first-generation hybridsin corn. Bull. rgr, B.P.L., 
U.S. Dept. Agr. pp. 45. 1910. 
™% Peart, R., and SurFace, F. M., Experiments in breeding sweet corn. Ann. 
Rep. Maine Agr. Exp. Sta. 1910.. pp. 249-307. Bull. 183. jigs. 220-233. 
*5 East, ., The distinction between development and heredity in inbreeding. 
Amer. Nat. 43:173-181. 1909. 
6 Op. cit. 17 Op. cit. 
*® Morrow, G. E., and GARDNER, F. D., Field experiments with corn 1892. 
Bull. 25, Ill. Agr. Exp. Sta. pp. 173-203. 1893. 
9 East, E. M., and Hayes, H. K., Inheritance in maize. Bull. Conn. Agr. Exp. 
Sta. pp. 137. pls. 25. 1911. 
