344 MUTATIONS IN EYE-COLOR OF DROSOPHILA. 



if the ordinary (red) white female in question lacks both the orange and th 



C factor. Thus 



' 



VPocX—VPocX White (red) 9 



VPoCX— Vpoc Eosin d" 



VPocXVPoCX Light-eosin 9 



VPocXVpoc White d" 



Crosses between the white male of orange stock with dark-eosin $ show that 

 and C are both absent from the orange-white stock also. Thus: 





VP0CX—VP0CX Dark-eosin 9 



>pocX — vpoc White (orange) c? 



VPoCXopocX Light-eosin 9 151 



VPoCXopoc Light-eosin <? 158 



At that time we did not have in stock whites of the Pink and Vermilion 

 stocks and could not make the same test with them, but there can be little 

 doubt that the whites of these classes also lack and C. 



If true it follows that all white-eyed flies are alike in that they lack both orange 

 and the color producer. They differ, as explained above, only in the presence 

 or absence of the factors for V and P. 



The Eye Color of "Permutants" Lacking V, P and 0. Fig. 5. 



Having flies that lack the orange factor, such for instance, as the dark-eosin 

 fly VP0CXVP0CX, and flies that lack the vermilion and pink factors but con- 

 tain C, such as the orange flies vpOC, it would seem possible by crossing and 

 extracting to obtain some that would lack the factors for V, P and but contain 

 C; for instance, vpoC. One might expect these flies to be white-eyed; for, they 

 would lack all the previously determined factors for eye-color, and possess only 

 the color producer. 



In order to make up flies of this sort we crossed dark-eosin females with 

 orange males. Such a combination would give red females and eosin males. 

 Those inbred should give the desired result as the following analysis will show : 



VP0CX—VP0CX Dark-eosin 9 



vpOCX — vpoc Orange c? 



VPoCXvpOCX Red 9 



VPoCXvpoc Light-eosin cf 



vPoCX VpoCX VPOCX VPoCX vpOCX vpoCX VpOCX vPOCX 

 vPoCX VPoCX vpoc Vpoc 







