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Scientific Proceedings (130) 



both influenced by environmental conditions it is of interest to 

 ascertain whether or not they react similarly to similar condi- 

 tions. The experiments dealing with this problem are still in 

 their preliminary stages, but certain general results have been in- 

 dicated even by the relatively crude methods used at first. Other 

 agents than temperature have been tried somewhat, but without 

 any definite results thus far. 



In the first experiment stock cultures of "bent" virilis were 

 exposed to different degrees of temperature — one at about 9°- 

 12° C, and others at approximately 16°, 23°, and 25° respectively. 

 Each bottle was left at the one temperature during the develop- 

 ment of the flies ; i. c, up to the time they began to hatch. The 

 three higher temperatures had no observable influence on the bent 

 character, the three lots of flies being essentially like those from 

 ordinary stock bottles of this race. The lot raised in the cold, 

 however, was markedly different. The most conspicuous differ- 

 ence was exhibited by the eyes. In ordinary bent stock of D. 

 virilis the eyes are lightly speckled, due apparently to a disar- 

 rangement of the hairs between the facets, and occasionally to a 

 slight disarrangement of the facets themselves. In flies reared 

 in the cold the eyes were decidedly roughened — almost all of the 

 facets being disarranged in some cases. In addition the posterior 

 cross-vein was broken in some individuals, the scutellar bristles 

 were disarranged in many, and other modifications were noted 

 here and there. The wing and leg characteristics, however, 

 showed no exaggeration whatever. In fact they seemed to be 

 less marked than usual. 



These results indicated that there was no correlation between 

 the effects on the eyes and those on the legs and wings, and also 

 that cold served to bring out several characteristics of bent that 

 do not appear at ordinary temperatures. They also led, of course, 

 to a similar experiment with the bent race of D. melanog aster. 

 In the latter the eyes are ordinarily normal, not speckled. But 

 when reared in the cold this race also showed the speckling of 

 the eyes. The gene for bent in melanogaster, then, seems to 

 have what may be called the potentiality for speckled eyes like 

 that of virilis, but requires a different environment for produc- 

 ing the effect. In other respects, also, the case parallels the pre- 

 ceding. The legs and wings are, if anything, less extremely af- 

 fected in the cold than at ordinary temperatures, and some of 



