No. 5S5] SHORTER ARTICLES AND DISCUSSION 579 



by crossing the males to their heterozygous sisters. The char- 

 acter is not sex linked ; it decreases the viability of the flies, but 

 more than this can not be said at present. Work is being con- 

 tinued on this character and on Hies with the character "tau." 



"Furrowed" is characterized by having the head foreshort- 

 ened, which causes indentations or furrows in the eyes ; also the 

 spines on the scutellum are stumpy. The last character is of 

 importance in determining some of the flies, as a female will 

 sometimes occur without any disturbance of the eyes. 



This character arose in a male which was crossed to a wild 

 female. The P 2 generation gave normal females and half the 

 males were normal and half were furrowed. This established 

 the fact that the character followed the distribution of the sex 

 chromosome. The position of the gene in the chromosome was 

 next determined according to the theory that the genes in any 

 chromosome are arranged in a linear series. 1 Crosses were made 

 with eosin miniature, sable forked, and with vermilion barred. 

 Because of the low fertility of the furrowed females the cross 

 was always made with the furrowed males. Consequently, the 

 males alone are considered in the counts given below. 



In the first column are the cross-over classes between mini- 

 ature and furrowed and the per cent, of these to the whole 

 number is 3.4. Then the gene which determines the character 

 "furrowed" is supposed to lie 3.4 points beyond miniature, or 

 at 39.6. 



Sable Forked $ by Furrowed J 



In the first column are the cross-over classes between furrowed 

 and sable and these are 5.7 per cent, of the entire number. 

 Then furrowed lies at a point 5.7 to the left of sable, or at 37.3. 



i Sturtevant, Jour. Ex. Zool., '13. 



