TWO NEW EYE COLORS IN DROSOPHILA MELANOGASTER. 2O3 



shown that in some cases external conditions (temperature) 

 change the amount of crossing over. 



Since the appearance of scarlet, the same mutation has been 

 found at Columbia University by D. E. Lancefield. Lancefield's 

 paper will be found in this journal. The two strains arose quite 

 independently, in laboratories remote from each other, and in 

 stocks that were absolutely distinct. They are identical in 

 appearance and in genetic constitution, and are due to the muta- 

 tion of the same gene, but the process of mutation occurred at 

 different times and in different localities. That they are due 

 to mutation of the same gene is demonstrated by crossing the 

 two stocks together, as I have done, using the stock kindly sent 

 me from Columbia and my own strain. The FI flies from this 

 cross were exactly like the parents. This origin of the same 

 mutation in two widely separated laboratories is of particular 

 interest, for here there is no possibility of contamination. 



The mutation rose occurred in the eyeless stock, but was not 

 observed until eyeless was crossed with scarlet. In color rose, 

 which is somewhat lighter than pink, is a shade lighter than peach 

 in older flies, but is practically identical with the latter at the 

 time of hatching. When rose was first observed there was no 

 peach stock kept in the laboratory. The three colors are very 

 similar when the flies are first hatched, but rose does not become 

 as dark with age as do the others. 



At the time when rose appeared, Dr. F. Payne had running in 

 the same laboratory stock of a new eye color identical in appear- 

 ance with rose. At that time it was thought that rose had been 

 derived from this stock by contamination. The gene for Dr. 

 Payne's eye color, called salmon, and as yet unreported, had 

 already been located in the sex chromosome. When salmon was 

 crossed with rose, the following results were obtained. 



f Salmon cf X rose 9 

 Cross I. s ... 



FI wild-type. 



fRose cf X salmon 9 

 Cross 2. ) 



I FI Salmon cf and wild-type 9 



These results indicated at once that the two eye colors are not 

 the same genetically, since rose is not sex linked. The FI when 

 inbred produced only the two eye colors, wild-type and salmon 



