544 



MARY B. STARK 



to 57 + 8.3 or 65.3 or at 65.6. The locus indicated by both 

 experunents when the data are weighted proportionately and a 

 correction is made for double crossing over is 66.2. 



In the spring of 1914, an interesting lethal turned up in my 



1910 stock. Half of the males hatched out as normal males but 

 of the other half, though able to pass through the different 

 stages of metamorphosis, many of them were unable to escape 

 from the pupa case. Those that chanced to do so fell over on 

 one side when trying to walk. I examined all the appendages 

 carefully but noticed no abnormalities. Nevertheless, the legs 

 did not seem strong enough to support the body, nor did they 

 seem to move coordinately and for that reason would so often 

 become entangled with one another that the fly could not get 

 them separated and would die from exhaustion in a day or so. 

 Not any of these males lived longer than two days. 



Whether the first lethal of the 1910 and the lethals of the 



1911 flies allow any development of the lethal bearing male 

 at all, is still under investigation. 



