. Carnegie Institution of Washington publication. 260 The Mechanism of Evolution in Leptinotaksa acting biotype 13. In figure 45 I have shown the behavior when biotypes 10 and 12, both from homozygous-acting extracted strains, are crossed. In F^, uniformly, type 4 is completely dominant and in F^ there is segregation, usually into three classes, on the average of 1:2:1, as far as this pair of char- acters is Fig. 45.—A second test made with respect to the same modified character as shown in figure 42. In the test (fig. 46) 6 reciprocal pairs were mated between Pg of the modified bi
. Carnegie Institution of Washington publication. 260 The Mechanism of Evolution in Leptinotaksa acting biotype 13. In figure 45 I have shown the behavior when biotypes 10 and 12, both from homozygous-acting extracted strains, are crossed. In F^, uniformly, type 4 is completely dominant and in F^ there is segregation, usually into three classes, on the average of 1:2:1, as far as this pair of char- acters is Fig. 45.—A second test made with respect to the same modified character as shown in figure 42. In the test (fig. 46) 6 reciprocal pairs were mated between Pg of the modified biotype 4 and biotype 12, and gave an F^ population all alike with biotype 4 dominant, 247 in all. Of these, 10 pairs mated gave progeny, an Fg generation in three classes, variable biotypes 4, 12, and typical biotype 4 nonvariable. Inbreeding each class in F3 showed the type 12 were true-breeding extractives F3 mm m J F2 I m ^ ^ ^- "I m Fig. 46.—Graphic representation of a further test between a selectively modified race crossed with biotype 12, showing that it was not modified but was the normal biotype 4 as far as its gametic com- position was concerned. in the 7 pairs tested, and that the biotype 4 nonvariable were pure, while vari- able biotype 4 were heterozygous dominants. At no point in these tests have any indications of gametic alteration in the biotype 4 as the result of the quan- titative accumulation of pigmentation been observed. In this entire experiment and its testing great care was exercised to keep out extraneous factors which might vitiate the series. At no time has there been any indication of gametic change. How, therefore, are these changes, often beyond. 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 Carnegie Institution of Washington. Washington, Carnegie Institution of Washi
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