EYE COLOR IN DROSOPHILA MELANOGASTER 



371 



the amount of dilution (degree) there seems to be a very sHght 

 difference. The fact that they are both in the same chromosome 

 (II) made essential a further test of their distinctness. The 

 method of linkage (a comparison of the star cream c value with 

 the star cream b value) would be crucial only in case the values 

 were quite different. An easier method, and one which at the 

 same time disposes of the question of allelomorphism is to make 

 a cross between the two types. When this was done (culture 

 5721) it was found that the Fi flies were standard eosin in color, 

 as is expected from the cross of two distinct recessives. Evi- 

 dently cream c is neither cream b nor an allelomorph of cream 

 b, and this is the only case where confusion w^as possible. 



SUMMARY 



The significant facts with respect to the origin and the inheri- 

 tance of these modifiers are summarized in table 27 in which 

 the primary arrangement is according to the order in which the 

 modifiers were discovered. The first four modifiers appeared in 

 rapid succession in the summer and fall of 1913 and were worked 

 out almost simultaneously. In 1914 three more were found, 



TABLE 27 

 Summary of the origin and inheritance of the specific modifiers of eosin 



