THE EVIDENCE OF THE ORGANS OF VISION III 



le 



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 c.e On 



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 

 by means of a camera 

 lucida, with the result 

 that the retina appears as 

 a bulging attached ventro- 

 laterally to the extremity of each gut-diverticulum, as is shown in 



A! 



Fig. 46. — The Brain, Eyes, and Anterior 

 Termination of the Alimentary Canal of 

 Artemia, viewed from the Dorsal Aspect. 



Br., brain; I.e., lateral eyes; c.e., median eyes; Al., 

 alimentary canal. 



A B 



Fig. 47.— A, The Formation of the Retina of the Eye of Ammoccetes (after 

 Scott) ;' B, The Formation of the Retina of the Eye of Ammoccetes, on 



MY THEORY. 



R., retina; l, lens; O.n., optic nerve fibres; Al., cephalic end of invertebrate ali- 

 mentary canal; V., cavity of ventricles of brain; Aid,, 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 



