EYE FACET NUMBER IN DROSOPHILA MELANOGASTER. l"Jl 



develop at these temperatures. In facet number, those which 

 developed at room temperature gave an average of 121 for the 

 males and 88 for the females, and differed but little from the 

 parents; those which developed at 17.5 averaged 153 for the 

 males and 149 for the females; and those which developed at 

 28.5 averaged 80 for the males and 45 for the females. In the 

 above experiment, the electric current of the incubator was turned 

 off for one and one half days so that the developing flies of the 

 warm set were at room temperature for that length of time. In 



TABLE IV. 



EXPERIMENT 4. FEMALES. 



the counts, the effect of this may be noted as about one ninth 

 of the flies is much higher than the rest, the developmental 

 period being nine days at a temperature of 28.5. The tem- 

 perature of the cold plate was allowed to rise to that of the 

 room twice for about three hours each time, so that the results 

 are somewhat less striking in this experiment than in some others 

 as regards the difference between high and low facet numbers. 



TABLE V. 



EXPERIMENT 4. i. MALES. 



