REACTIONS TO LIGHT AND GRAVITY IN DROSOPHILA 73 
TABLE 12 . 
GROUP II.- WINGS CUT 
: ‘ if 
GROUP I WINGS NOT CUT ONE-FOURTH 
Light Gravity Light Gravity 
Male |'Female| Male | Female} Male | Female} Male | Female 
Before cutting...... S54 call (anc ‘82.5 | 2a We26eGr | SOLOF | S8ron |) 20.0) || 24:9 
MEMpPeravUres a... peau «4. « 23.9 23 .5° 
Wrrereutting......2: 0:5. o1.6 | 92.5 | 48.1 | 48.3 | 76.6 | 72.5 | 40.0 | 36.6 
semmperatune: senses ae 24° 24° 
GROUP IV. WINGS CUT 
GROUP III. WINGS CUT HALF THREE-FOURTHS 
Berar catia dy eee 80.0 | 95.3 | 41.6 | 42.5 | 90.8 | 95.8 40.8 | 38.3 
EMpPCratunes issn cscs ae 23.5° 23.5° 
After cutting..............] 19.1 | 21.2 | 65.0 | 49.0 | 25.8 | 26.3 | 61.6 | 49.9 
Memperatunenssce- eo ee oe 24° 24° 
It is evident from these figures that with a single exception, 
such as the case of the groups in which three-fourths of the wing 
was removed, these results support the conclusion that the de- 
crease in phototropism is directly proportional to the amount of 
the wings removed. Moreover, in considering this result and 
particularly the one exception, it must be remembered that the 
amount of wing cut off in each group was directly proportional to 
the height of the index originally scored by that group in the 
initial tests. Thus, the group having three-fourths of the wing 
removed was originally the fastest of all, and this may account 
for its still retaining enough speed to win out over the group 
with only one-half of the wing removed. ‘This seems particu- 
larly probable when this experiment is considered together with 
the previous one. Taking the two together, I believe we are 
justified in the conclusion that at least roughly speaking the pro- 
portion between phototropism and wing length holds good. 
