194 PHINEAS W. WHITING. 



succeeding generation averaged much more bronzy in appearance 

 than the preceding. At the close of the experiment in the F 3 

 generation, properly the second generation of selection, prac- 

 tically all the flies assumed considerable of the bronzy color 

 before they were examined, which was done once every day. 



In the selection in the opposite direction the results were not 

 as striking. A female of L. sericata, 1913-7% was taken near the 

 Bussey Institution, March 19, 1913. She was chosen because 

 she appeared greener than many of the others that were seen 

 about the building. In a few days she deposited eggs from which 

 24 males and 19 females were reared. Many of these were 

 bronze-colored as soon as they had hardened but a few were 

 green after a period of two or three days with but a slight amount 

 of bronze. A single mating obtained from a pair of these latter 

 gave 93 males and 90 females which averaged much greener 

 than the second generation of the red selection i()i2-E. At this 

 point the experiment was cut short by the death of the flies 

 selected. 



The flies of both the red and the green selections were placed 

 in boxes and allowed to become dry. It was intended to group 

 them into classes according to color and thus to demonstrate 

 more clearly the hereditary nature of the bronzing factors. After 

 the specimens had dried, however, it was observed that the 

 pigment had changed considerably, the reds becoming much 

 greener and the greens often being streaked with blue. It was 

 therefore found necessary to abandon this more accurate proof 

 of the hereditary nature of the bronzing until such time as 

 another selection could be made and the colors of the flies 

 recorded as soon as killed by comparison with standard color 

 charts. 



Experiments are now under way which it is hoped will throw 

 more light upon the conditions governing the life histories and 

 habits of these flies. 



My thanks are due to Mr. C. T. Brues for helpful criticism in 

 the preparation of this paper and for many suggestions through- 

 out the course of the work. 



