The elements of genetics (1950) (21262823541)

Title: The elements of genetics

Identifier: elementsofgeneti00darl (find matches)

Year: 1950 (1950s)

Authors: Darlington, C. D. (Cyril Dean), 1903-; Mather, Kenneth

Subjects: Genetics

Publisher: New York : Macmillan

Contributing Library: MBLWHOI Library

Digitizing Sponsor: MBLWHOI Library

Text Appearing Before Image:

BASES OF CHANGH in chimaeras which themselves have arisen from a single original mutation (cf. Fig. 22). In animals the effects of somatic mutation are slightly different. Development and life being limited, the mixture is not a permanent one. Development being less simple the mixture is also less regular. As a result, the changed cells give flakes and sectors instead of layers

Text Appearing After Image:

Fig. 23.—Gynandromorph of Drosophila melanogastcr. The left side is XX and female. One X carrying the dominant gene Notch, whose effect appears in the left wing, has been lost on the right side which is therefore male and shows the effects of the recessive genes of the other X, viz. ruby (eye colour), scute (bristle reduction), broad (wing), and forked (bristle gnarling). The whole fly is slightly warped owing to the male side being shorter than the female (from Morgan, Bridges and Sturtevant, 1925). and the product is known as a mosaic instead of a chimaera. There is, however, one regular type of mixture of particular interest and this is the gynandromorph. Such monsters, male in one part and female in the rest, arise from a genetic difference between a pair of nuclei produced at an early mitosis in the embryo. They give various mixtures according to the stages and relative positions of the mitoses, but perhaps the commonest is the half-sidcr of the type shown in Fig. 23. They come about in a variety of ways as can be proved by genetic as well as by cytological evidence (Fig. 24). 1J2

1950 books genetics files fine grained classification needed gynandromorph illustrations book illustrations natural history high resolution images from internet archive

1950

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