82 ; ROBERT STANLEY McEWEN 
TABLE 15 
Temperature 24° 
LIGHT GRAVITY (VERTICAL) 
Male | Female | Male | Female 
(C6) £0) 5 an as eee ane wee OER SERS ARE ere 3 20.0 7.5 31.6 24.1 
(GEOUDB ee ose nee ae eect re 13.3 10.0 24.1 20.8 
Group Giza ce eee ae eRe Re PoE 10.0 1G; 42.5 35.0 
OGAIS (tba eye ata tare eieea, Cre ate 43.3 29.1 98.2 79.9 
VET AG Cee tyres ous tbe en recs eee Pes 14.4 9.7 32.7 26.6 
lamp in the gravity trials was used in the first tests of the males 
in Groups A and B. After the first test the males of Group A 
were kept as a control, while those of Group B suffered the re- 
moval of the rather poorly developed wings which they possessed. 
Both sets were retested 8 hours later. Table 16 gives the 
results: 
The results from this experiment are enough to suggest strongly. 
the slight increase in phototropic response which might be ex- 
pected to distinguish these flies from the vestigials. The most 
TABLE 16 
BEFORE WING REMOVAL AFTER WING REMOVAL 
ees ign) |) Gas a ||) Vea 
Male | Female O Male Female] Male | Female} Male | Female 
Temperature 24° es: 
Group Ar «4: { ; =e ret ee Wee 
Group) Be oe { ; 2223 000 63.8 68.4 
Temperature 23° 
Group C5728 1 10.0| 24.1 | 41.6} 48.3 
Motalecwpcens- ce as 147.0) 41.7 | 202.8} 79.1 63.8. 68.4 
PAY ORAS ES He mares O74) 2083) || S07) sy || Oss 68.4 
