. Contributions to the genetics of Drosophila melanogaster. Drosophila melanogaster; Heredity; Karyokinesis. THE ORIGIN OF GYNANDROMORPHS. description of a few of them was published we have continued to keep records of their occurrence. Others, too, working with our mutant types have found them, and a few have been described by Dexter, Duncan, and Hyde. We soon reahzed that they occurred with suffi- cient frequency to make it possible to devise experiments of a sort to furnish the long-sought criterion as to the most common method of their occurrence. It is this evidence on which we wish now t
. Contributions to the genetics of Drosophila melanogaster. Drosophila melanogaster; Heredity; Karyokinesis. THE ORIGIN OF GYNANDROMORPHS. description of a few of them was published we have continued to keep records of their occurrence. Others, too, working with our mutant types have found them, and a few have been described by Dexter, Duncan, and Hyde. We soon reahzed that they occurred with suffi- cient frequency to make it possible to devise experiments of a sort to furnish the long-sought criterion as to the most common method of their occurrence. It is this evidence on which we wish now to lay chief emphasis. The ordinary gynandromorph is an animal that is male on one side of the body and female on the other. The reproductive organs, gonads, and ducts may or, in bees at least, may not show a corre- sponding difference. A typical case of a gynandromorph that is bilateral, at least superficially, is represented in plate 1, figure 1. For a long time it has been recognized that bilateral gynandromorphism is only one kind of abnormal distribution of the sex characters; even in the classical case of the Eugster bees (see p. 74) other distributions of the characters were recorded. In the fly represented in plate 3, fig- ure 2, the upper part of the abdomen is female, but the lower side of the abdomen, notably the external genitalia, are male. In the individual represented in plate 3, figure 5, the left anterior side of the head is male, the right fe- male, while the left posterior parts of the body are female, the right male. Other cases will be described later in which even more irregular and complex distributions of male and female parts exist. Before discussing these and other cases in detail, it may be well to give three of the most recent interpreta- tions of gynandromorphism resting on a chromosomal basis and the criteria by which the validity of each has been tested. In 1888 Boveri suggested that on rare occasions a spermatozoon, on entering the egg, might be d
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