172 WILLIAM J. DAKIN 
EXPLANATION OF PLATE 7. 
Illustrating Prof. W. J. Dakin’s paper on ‘ The Eye of 
Peripatus ’. 
Fig. 1—The Eye of Peripatoides occidentalis in vertical 
section (longitudinal through the eye). The right half of the retina is 
represented in the depigmented condition, the left side in the natural 
state. x 740, Cor.=cormea; Cut. = cuticle; Sub. Cor. = subcorneal 
layer; Op. N.= optic nerve; Hpid.= epidermis; Mus. = muscle-cells ; 
L. = lens, 
Fig. 2.—Complete rod-cell with rod isolated from the retina. Macera- 
tion preparation. x 1,500. Pig. = pigment; Nuc. = nucleus of rod-cell. 
Fig. 3.—Transverse section through retina in plane of the rods (stained 
haematoxylin, Ehrlich). x 1,500. 
Fig. 4.—Transverse section through retina, in plane of rod-cells in 
the region where pigment is present. (Depigmented section.) x 1,500. 
Fig. 5.—Diagrams illustrating the development of the Eye of Peripatus. 
(a) Invagination of ectoderm. 
(b) Invagination of ectoderm complete. 
(c) Ectodermal vesicle cut off. 
(d) Proximal cells give rise to retina, the distal becomes the sub- 
corneal layer. 
(e) Retina developed, lens secreted by cells of vesicle. 
