REACTIONS TO LIGHT AND GRAVITY IN DROSOPHILA 101 
affects little if at all the response to gravity. The effect is 
roughly proportional to the amount of the wing cut off. It is 
not a result of the operation as such, since other operations do 
not produce it, and because wingless flies and flies of other 
stocks with defective wings show the same deficiency of response. 
Certain organs (fig. 3) occur on the wings of Drosophila, but 
operations fail to show that they are connected with the response 
Showing relative tropism of flies of varied eye colors toward lights of different 
wave lengths 
White Eyed Flies, 
lt _ i 
(+n A 
Red Ps) es 
dammed Eyed ties 
| a ae 
ES 
Red 
Eosin Eyed Flies 
| FERS See 
_ a 
Red SEMRAE eA 
Vermilion Eyed Flies 
|. a 
5 << 
eC IE 7 
Normal Eyed Flies 
| eo aa 
i RE aS 
“| SARS ee ea 
Sepia Eyed Flies 
|. AGES 
Cc 
\ | RRS! 
Graph 5 
