THE EVIDENCE OF THE ORGANS OF VISION 111 
sections through the whole animal, and, as mentioned in my paper 
in the Journal of Anatomy and Physiology, he discovered that the 
retinal ganglion of each 
lateral eye is so closely 
attached to the end of the 
corresponding diverticu- 
lum of the gut that the 
lining cells of the ventral 
part of the diverticulum 
form a lining to the reti- 
nal ganglion (Fig. 45). In 
this animal there are only 
two gut-diverticula, which 
are situated most ante- 
riorly. I have plotted 
out this series of sections Fic, 464—Tur Brain, Eyrs, anpD ANTERIOR 
by means of a camera TERMINATION OF THE ALIMENTARY CANAL OF 
lucida, with the result ARTEMIA, VIEWED FROM THE DorsaL ASPECT. 
that the retina appears as 
a bulging attached ventro- 
laterally to the extremity of each gut-diverticulum, as is shown in 
Br., brain; 1.e., lateral eyes; c.e., median eyes; AL., 
alimentary canal. 
Fic. 47.—A, Tas Formation oF THE Retina OF THE Eyre or AmMmoce:tss (after 
Scorr); B, THz Formation oF THE RETINA OF THE EYE OF AMMOC@TES, ON 
MY THEORY. 
R., retina; 1., lens; O.2., optic nerve fibres; Al., cephalic end of invertebrate ali- 
mentary canal; V., cavity of ventricles of brain; Al.d., anterior diverticulum 
of alimentary canal; op.d., optic diverticulum. 
Fig. 46. It is instructive to compare with this figure Scott’s picture 
of the developing eye in Ammoccetes, where he figures the retina as 
