Linkage Data. 39 



pressed has been lost and we are unable to make a detailed comparison. The de- 

 scription of telescoped suggests that of the character "furrowed" in D. melanogaster 

 (Morgan and Bridges, 1916). This is not borne out by a detailed comparison, how- 

 ever, for the modifications are not alike in the two cases. 



Garnet (G). 



Description. — Garnet is an eye-color character in which the color is very close to 

 Ridgeway's garnet-brown. It is almost indistinguishable from the sex-linked char- 

 acter magenta, but differs in being a dominant. It is uniform and regular in appear- 

 ance, and promises to be a very useful character. Pure stock has not yet been 

 obtained, but from one mating of garnet by garnet (M 101) all of the 51 offspring 

 were garnet, indicating that one parent was probably homozygous. Tests are now 

 under way to determine whether or not garnet is lethal in the homozygous condition. 

 Its viability is excellent. Heterozygous flies outcrossed gave 231 garnet to 240 

 not-garnet offspring (M 13, 18, 19, 42, 99). 



Origin. — (M 13.) The origin of the garnet is not definitely known. It was found 

 in a bottle of mixed stock carrying the sex-linked characters vermilion and singed, 

 and supposedly magenta also. Tests revealed the presence of a dominant eye-color 

 resembling magenta, but no actual magenta. How long this character (garnet) had 

 been present is not known. 



Comparison. — So far as we are aware, this is the only dominant mutant eye-color 

 character of this sort known in any species of Drosophila. 



LINKAGE DATA. 

 Detection of Linkage in Group III. 



Scaly and telescoped. — Scaly and telescoped were shown to belong 

 to the same group by back-crossing males heterozygous for the 

 respective genes (in opposite chromosomes) to telescoped females. 

 The following count was obtained (V 1220, 1244, 1252): scaly 116, 

 telescoped 110, wild-type 0, telescoped scaly 0. (See also under 

 scaly, hunch, and telescoped.) 



Steel and telescoped. — The linkage of these two characters was 

 detected when a heterozygous male was back-crossed to a double 

 recessive female. This mating (V 1191) gave: telescoped 12, steel 13, 

 wild-type 1, telescoped steel 0. The one wild-type fly doubtless 

 belongs in the steel class, but failed to show the spot in the eyes. 

 F2 counts also indicated linkage by the absence of the double recessive 

 class. 



Hunch and telescoped. — Both F2 and back-cross counts indicate 

 linkage between these characters. Four Fi matings (L 376, 388, 394, 

 400) gave the following total of F2 individuals: telescoped 67, hunch 

 74, wild- type 162, telescoped hunch 0. The back-cross data are 

 given in the following paragraph. 



Scaly, hunch, and telescoped. — Two back-cross matings using heter- 

 ozygous males, with scaly in one chromosome and hunch telescoped 

 in the other, by homozygous hunch telescoped females gave the fol- 

 lowing totals: hunch telescoped 132, scaly 202, wild-type 58, hunch 0, 

 telescoped 0, scaly hunch 0, scaly telescoped 0, scaly hunch tel- 



