File:The American Museum journal (c1900-(1918)) (18133405616).jpg

Title: The American Museum journal
Identifier: americanmuseumjo09amer (find matches)
Year: c1900-(1918) (c190s)
Authors: American Museum of Natural History
Subjects: Natural history
Publisher: New York : American Museum of Natural History
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: Biodiversity Heritage Library

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getting mates as those which possess it, although strong evidence of sexual selection with respect to other characters is being obtained. It is generally believed that close inbreeding is always attended by decreased vitality and disuse by degeneration. This is not the case with Drosophila ampelojyhila. It has been repeatedly V)red for a large number of generations, matins: lirother and sister, without disastrous results. I have, furthermore, made careful measurements of the wings of successive generations and found that although my pedigreed stock has not l)een allowed to fly for more than fifty generations, there has been no defeneration of the wino- either as to size or as to venation. On the other hand, by selective breeding I have been able to get specimens with greatly reduced wing venation as is shown in Figure 2, Figure 3 showing the normal wing. Selection in the other direction, i. e., for increased venation, is just as effective (Fig. 4). A study of the inheritance of these variations was begun at the Station for Experi- mental Evolution of the Carnegie Institution and is being continued, with other mathematical and exper- imental studies of evolution, at the Museum. About 200,000 pedigreed individuals of this species alone have already been obtained. The inter- pretation of the results of this work is complicated by the fact that the two sexes display the abnormalities to unequal degrees and also because the mode of inheritance deviates strongly from exj^ectation on the basis of the commonly accepted laws. F. E. LuTz. Fig. 3.

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