. The physical basis of heredity . Fig. 4.—Male and female vinegar fly (Drosophila melanogaster). In the preceding illustrations the character differencebetween the two races is supposed to show itself in thesame environment. It has been found in a few othercases that the dominance of one character over the othermay depend on the environment. For example, in thenormal vinegar fly the black bands of the abdomen showgreat regularity (Fig. 4), but in a mutant race calledabnormal abdomen (Fig. 5) the bands may be irregu-larly broken up, or even absent. In cultures with abund-ance of fresh food and
. The physical basis of heredity . Fig. 4.—Male and female vinegar fly (Drosophila melanogaster). In the preceding illustrations the character differencebetween the two races is supposed to show itself in thesame environment. It has been found in a few othercases that the dominance of one character over the othermay depend on the environment. For example, in thenormal vinegar fly the black bands of the abdomen showgreat regularity (Fig. 4), but in a mutant race calledabnormal abdomen (Fig. 5) the bands may be irregu-larly broken up, or even absent. In cultures with abund-ance of fresh food and moisture, all the individuals havevery irregular bands, but as the culture gets old, and the MENDELS FIRST LAW 29 food and moisture become less and less, the bands becomemore and more regular until at last the flies are indistin-guishable from normal flies. If a cross is made betweena female with abnormal bands and a wild male, the off-spring that first hatch under favorable conditions are allvery abnormal. Here abnormal comple
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectheredit, bookyear1919
