File:Contributions to the genetics of Drosophila melanogaster (1919) (20502580599).jpg

Title: Contributions to the genetics of Drosophila melanogaster
Identifier: contributionsto00carn (find matches)
Year: 1919 (1910s)
Authors: Carnegie Institution of Washington; Morgan, Thomas Hunt, 1866-1945; Bridges, Calvin B. (Calvin Blackman), 1889-1938; Sturtevant, A. H. (Alfred Henry), 1891-1970
Subjects: Drosophila melanogaster; Heredity; Karyokinesis
Publisher: Washington, Carnegie Institution of Washington
Contributing Library: NCSU Libraries
Digitizing Sponsor: NCSU Libraries

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THE ORIGIN OF GYNANDROMORPHS. 19 pronouncement as to the sense in which the phrase is employed; otherwise it is Httle more than a play on words. For instance, when one X chromosome is present the individual is a male, which means that one X plus all the rest of the cell makes a male, and when two X's are present, these two plus all the rest of the cell make a female. In what sense can such a statement be twisted to mean that each such combination contains in a latent condition the opposite condition? Compare the facts with a similar chemical situation and the absurdity of the inclusion hypothesis is evident. Maltose has the formula C12H22O11 and glucose the formula C6H12O6. One is twice the other minus one H2O. To state that maltose contains glucose latent or that glucose contains maltose latent is obviously absurd, yet this does not differ much from the view that each sex contains the opposite one in latent form. De Meijere thinks that gynandromorphs can be explained in "that the activation of the opposite sex (opposite to the one already under way) has started in, relatively later, after all the parts have taken on their definite positions; many of the parts have gone too far in the first direction, i. e., they are too old, but those that have not may be turned aside and produce the oppo- ^ ^ site results."^ This view is offered to account for mosaics of sex char- acter. The bilateral gynandro- morph, he supposes, owes its origin to the above changes having taken place very early, even at the first division. De Meijere thinks ap- parently of effects being produced by external factors of some unknown kind rather than internal ones connected with a sex mechanism. His idea is too vague to be of use and too remote from present-day knowledge about sex determination to call for extended criticism. . Arnold Lang, accepting the same general conception of sex and expressing what he beheved to be the real relations by means of the formulae that Goldschmidt had advocated, offered another possible interpretation of gynandromorphs that is superficially exactly like the theory of chromosomal ehmination which the results in Drosophila show to hold for this insect. In fact, Lang's view, if divested of the unnecessary encumbrance of De Meijere's conception and of Gold- schmidt's formulae, is then identical with the theory of chromosomal elimination. For example, Lang represents the fertilized egg (one that will give rise to a female) by the scheme shown in text-figure 4. The primary sex characters for the male are M carried by a pair of
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