1918.1 FIELD CEOPS. 531 



hours, showed 7 per cent more vigor, and nearly the same variability as smaller 

 kernels of the same texture. 



The tests suggest that in somewhat favorable conditions for seedlings there 

 may be a practical method of eliminating the weaker ones, thus leaving only 

 those that will give better final results than when all plants from a lot of seed 

 are grown under highly stimulating conditions. This results in a method, of 

 selection, and an application to crop growing of the general law of the survival 

 of the fittest. Any conditions of the seed bed that tend to show the degree 

 of vigor of the seedlings are deemed essential in the vital test, and there is 

 a possibility that a lack of either heat, moisture, or light, the leading physical 

 environmental factors, may give the desired result. With such small seeds 

 as those of tomato, eggiilant, pepper, etc., a lack of high soil fertility may 

 suffice. 



Inheritance of a mosaic pericarp pattern color of maize, H. K. Hayes 

 (Genetics, 2 (1917), No. 3, pp. 261-281, pi. 1, fig. Jf).— The author describes ex- 

 periments with a mosaic pericarp pattern color of maize to study the behavior 

 of this character in continued selection of plus and minus variates this char- 

 acter having exhibited a high degree of variability. The subspecies Zea mays 

 indurata, known as " brindle flint," was used but did not prove to be homozy- 

 gous for the character from which it takes its name ; consequently, attempts 

 were made to produce homozygous races by self-fertilization. From 1909 to 

 1914. the work was conducted at the Connecticut Experiment Station and 

 since 1915 at the Minnesota Experiment Station. 



Selection experiments have isolated the following types which breed com- 

 paratively true: (1) Self-red pericarp, (2) pure for variegation but with a 

 range of variability from ears with only a few seeds with deep red stripes 

 to ears in which nearly all seeds are quite heavily covered with red striations, 

 (3) very slight pattern color which under the microscope appears to be due 

 to the presence of a faint color in some of the pericarp cells, and (4) an 

 uncolored pericarp race. Selection within the second type has not succeeded 

 in isolating strains which breed true for the amount of variegation, extreme 

 minus types tending to give progeny containing more ears of the minus type 

 than are obtained from extreme plus types. Heavily striated, self-fertilized 

 ears proved to be heterozygous, giving a progeny which segregates for one 

 factor difference. The very deeply variegated, heterozygous, self-fertilized ears 

 produced progeny having a greater proportion of variegated segregates deeply 

 variegated than was obtained in the progeny of less deeply variegated, self- 

 fertilized, heterozygous ears. 



Crosses ai'e reported with the homozygous types noted above and the results 

 obtained may be briefly summarized as follows : A cross between the self-red 

 selection and the homozygous variegated type gave an intermediate Fi having 

 ears more deeply striated than the homozygous variegated race. The Fj grown 

 from self-fertilized Fi ears showed a segregation of self-red, Fi, and homozygous 

 types, as expected, for one unit factor difference. Back crosses of the Fi with 

 parental strains gave parental and Fi types in a 1 : 1 ratio. 



A cross between the self-red selection and pattern selection showed a domi- 

 nance of the self-red type in Fi, and in Fz a segregation of self-i-ed and pattern 

 types, in a 3 : 1 ratio. 



A cross between the homozygous variegated selection and the pattern selec- 

 tion gave increased variability in Fi, shown by ears of a higher grade in varie- 

 gation than the parental variegated race and by the production of a considerable 

 proportion of bud sport ears. In the Fz some self-red ears were obtained. Pat- 

 tern ears bore the proportion to other grades of 1 : 2.3. 



