108 W. H. TALIAFERRO 
the rhabdomes confined to a definite area; that, in such areas, 
there is always a large proportion of the rhabdomes which have 
their longitudinal axes parallel with the rays of light; and that, 
in a number of cases, the longitudinal axes of all of the rhabdomes 
in the illuminated area are nearly parallel with the rays of light. 
Fig. 18 Diagram representing the relation of the axis of photic stimulation 
to the axes of the various rhabdomes when the eye is illuminated from different 
directions. The diagrams are made from camera-lucida drawings of sections. A 
and B, frontal sections of the eye; C and D, transverse sections of the eye; A-P, 
antero-posterior line; D-V, dorsoventral line;a, b, c, d, arrows indicating the dif- 
ferent beams of light; ac, accessory cells; p, pigment-cup; 1-9, rhabdomes. 
