No. 578] DBOSOPHILA AMPELOPHILA 



99 



fore directed to the condition of the food inside the bottles. 

 An examination seemed to indicate that those in which the 

 food was dry yielded the higher pink ratios. To test this, 

 two of the bottles in which conditions were normal, and 

 in which the F 2 had just begun to emerge, were made 

 1 1 wet" by the addition of a considerable amount of banana 

 juice. But they still showed a similar tendency to yield 

 a relatively higher proportion of pink. 



To ascertain more definitely whether or not moisture 

 or dryness affected in any way the development of these 

 flies, a special experiment was arranged in which some 

 flies were bred in 4 'dry" bottles, and some in "wet" 

 bottles. In the first case, the banana was thoroughly 

 dried by means of filter paper which was discarded after 

 it had absorbed all the available moisture, and the banana 

 wrapped in fresh paper ; in the second, banana juice was 

 added every second or third day, so that there was 

 throughout the experiment an abundant amount of wet 

 food in the bottles. The effect of this treatment is shown 

 in Tables III and IV: 



TABLE III 



