100 ROBERT STANLEY McEWEN 
TABLE 28 
Sepia eyed flies 
Group A 
AVERAGE 
SEX Wa R G 
Sex Violet Red Green 
ise | {fab OO). Meigs. o. - 93.9 87.4 66.0 
Male..... 2daiel 5 |0 | Female 93.9 91.0 68.0 
SaaiO) a Om a6 | 
istales 3 Tied 
Female..<|2d|2 |3 |0 Female ie ence 
SaMTallio 6b b. Tied once 
Group B 
TsO OW Ome PVialess asee 93.3 70.4 54.5 
Male.....<|2d |}0 |6 | 0 | Female... 96.6 86.6 55.0 
stl OG eG 
sta 6. 1000 
Female. . 2d | 0 6 | 0 
tel | OO) ee 
Groups A and B combined 
Ist |11 1 OMEMalessee: 93.6 78.9 60.2 
Male..... As oil > |ulal 0 Female... 95.2 88.8 61.5 
Sol CO) = ah (8). | 
Ist | 9 3 0 ; 
Female... <|2d |2 |9 | 0 Female ‘e He at 
3d | 1la|0 |12b ; 
SUMMARY AND CONCLUSIONS 
1. Females of Drosophila ampelophila react to light somewhat 
more readily than do the males. This difference is most marked 
in young insects and steadily decreases with age, until at 8 or 9 
days it has almost vanished. The time of maximum activity for 
both sexes does not seem to come at 18 hours, but more probably 
at from 3 to 5 days. 
2. The removal of the wings causes the fly to lose most of its 
phototropism. The effect is specifically on the tendency to re- 
act to light, as is shown by the fact that such an operation 
