Vol. XXX V. October, 1918. No. 4. 



BIOLOGICAL BULLETIN 



TWO NEW EYE COLORS IN THE THIRD CHROMO- 

 SOME OF DROSOPHILA MELANOGASTER. 



MILDRED HOGE RICHARDS, 

 CRAWFORDSVILLE, INDIANA. 



In the cultures of Drosophila mdanogaster which I have been 

 breeding at Indiana University, two new eye colors have lately 

 appeared. One of these, rose, closely resembles pink and peach 

 of the third chromosome, and is allelomorphic to them. The 

 other eye color, scarlet, is a bright red much like the vermilion 

 of the first chromosome in appearance, but quite distinct from 

 it genetically, for it is located on the third chromosome. 



Both eye color mutations occurred in the winter of 1916. 

 Scarlet appeared (November 18, 1916) in a wild stock which was 

 being used in a temperature experiment. Rose appeared (Janu- 

 ary 9, 1917) after scarlet had been crossed to eyeless, and later 

 was found in the eyeless stock, so that the mutation evidently 

 had occurred there. 



A series of temperature experiments was undertaken in the 

 fall of 1916 in the effort to determine whether it would be possible 

 to adjust a strain of Drosophila to a temperature abnormally 

 high for that species. The flies were bred in pairs, the tempera- 

 ture of the incubator usually being maintained at 27-31. Each 

 generation of flies was raised, during the greater part of its period 

 of development, at this higher temperature. The flies would 

 not lay, however, under the abnormal conditions; they were 

 allowed to mate, therefore, at room temperature, after which 

 they were transferred to the incubator. The larvae having 

 pupated, the cultures were again removed from the incubator, 

 for the heat proved fatal to the pupa stages. Even with these 



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