104 W. H. TALIAFERRO 
a localizer of photic stimulation as maintained by Hesse. The 
localizing mechanism appears to be contained in some manner 
in the rhabdomes themselves. 
A 
----> 
B 
a ; 
<—__ 
A\ ee C\ 
—_——_—_ 
: 
D 
Fig. 16 Illumination of eye with light coming from different directions. A 
and B, animal possessing entire right eye; C and D, animal possessing anterior half 
of right eye. Arrows indicate the direction of rays of light; broken lines indicate 
path of specimen; x, position of rhabdomes which are illuminated. Animal D 
proceeds directly away from the light although the same rhabdomes are being 
illuminated as in C when it turned sharply to the left. 
The idea suggested itself to the author that the above con- 
clusion might not be valid because of the possibility that in 
removing the posterior half of the eye the pigment might be 
