CALVIN B. BRIDGES 



655 



TABLE IX, 



. /V-S V \ 



Of spring of Vermilion Females, Constituhon I — —J, 



Constitution {V-S v ). 



and Wild-Type Males, 



Apr. 23, 1917. 



Haploid and Cytological Tests of the Extent of the Deficient Region. 



Another method of getting Hght on the extent of the deficient re- 

 gion is by testing whether the deficiency works for other mutations 

 in the same manner as with vermihon. Tiny-bristles and minia- 

 ture were known by the linkage tests to be outside the region so that 

 the failure of both to give pseudodominance was not unexpected. 

 The only other mutant whose locus was close enough to be worth 

 while testing was ''ocellar-bristles" whose locus is to the left of ver- 

 milion by one or more units— not accurately located because of the 

 poorness of the character. This mutant also failed to give pseudo- 

 dominance so that its locus Hes outside the deficient region.- 



Considerable cytological work was undertaken, but none of the 

 slides were good enough technically to be able to demonstrate the 

 deficiency cytologically. 



Dominant Action of Deficiencies. 



The stock of vermilion-deficiency was unusually difficult to main- 

 tain, being on the verge of extinction several times before its final 

 loss.' The same fact was observed with respect to the orginal forked- 

 bar-deficiency and all the notch stocks, which have been lost (ex- 



