. The elements of genetics. Genetics. COILING RIGHT LEFT. Rr Rr F, lRR+2Rr+lrr 1 £ s£i 3 Families all right 1 Family ALL left Fig. 45.—The direction of coiling of the shell in Liimica pcrc^ra is determined by a single gene difference, the allelomorph giving right-hand coiling being dominant to that giving left. The direction of coiling reflects, however, not the snail's ov^n genotype but that of its mother. Thus all the offspring of a female have the same direction of coiling, even though she be a heterozygote. The segregation will appear in the phenotype as differences between the families of
. The elements of genetics. Genetics. COILING RIGHT LEFT. Rr Rr F, lRR+2Rr+lrr 1 £ s£i 3 Families all right 1 Family ALL left Fig. 45.—The direction of coiling of the shell in Liimica pcrc^ra is determined by a single gene difference, the allelomorph giving right-hand coiling being dominant to that giving left. The direction of coiling reflects, however, not the snail's ov^n genotype but that of its mother. Thus all the offspring of a female have the same direction of coiling, even though she be a heterozygote. The segregation will appear in the phenotype as differences between the families of grandchildren. In this way the reciprocal F^'s differ in the cross between true breeding strains of right and left coiled snails. The F2's from these reciprocals, however, are alike and are also uniform. The segregation among the genotypes of the 's shows itself only in the F3 generation which consists of 3 families of uniformly right coiled snails to i of uniformly left coiled snails, no matter which way the original cross was made. 192. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Darlington, C. D. (Cyril Dean), 1903-; Mather, Kenneth. New York : Macmillan
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Keywords: ., bookcentury1900, bookpublishernewyorkmacmil, booksubjectgenetics
