34 



THE ORIGIN OF GYNANDROMORPHS. 



Within each subdivision the arrangement of the cases is according 

 to the order of discovery, that is, by date, except that the colored 

 figures are taken out of order and described first in each group. 



Each case is known by a number, which is usually that of the culture 

 bottle in which the gynandromorph was found, but in some cases 

 letters or small numbers are used, which, however, correspond to the 

 bottle in which the specimen is preserved or the order in which the 

 descriptions were first arranged. The date, the finder, and the type 

 of illustrations are also indicated on the number line. 



The information on each case is then given in the order. Parentage, 

 Description, and Explanation. In many of the cases the explanation 

 is followed by a diagram showing at the left the two X chromosomes of 

 the zygote, which at the same time represent the female parts of the 

 gynandromorph, and at the right the single X that is left after elimina- 

 tion, which gives the constitution of the male parts. In case somatic 

 reduction was involved the leftmost set of chromosomes represents 

 the initial condition of the zygote, and the other two sets to the right 

 the resulting two conditions, whether male or female. 



A knowledge of the order and the relative spacing of the genes along 

 the chromosome is indispensable, and we have therefore made a list 

 of the sex-linked mutants mentioned, with their symbols and the 

 approximate locus of each : 



The figures in the plates are camera-lucida drawings of etherized 

 living flies, but in the following descriptions of the gynandromorphs 

 diagrams only are given (except in rare instances). These diagrams 

 were made from the flies themselves, which are preserved in alcohol. 

 All drawings and diagrams were made by Miss Edith M. Wallace, 

 to whose skill and accuracy they bear witness. 



