26 UNIVERSITY OF MISSOURI STUDIES [^14 



any indication of a true eye present. Sections of an eye in this 

 condition show no well defined structures distal to the optic 

 ganglion except the lamellated cuticle (Fig. 21, PI. III). 



Another conspicuous difference between a normal eye and a 

 regenerating one is the rough jagged surface that the regener- 

 ating eye presents. Such an eye lacks the symmetrical form of 

 an uninjured one. I have always attributed these irregular out- 

 lines chiefly to the crushing and cutting of the eye when it was 

 operated upon. After a moult the eye is often more regular and 

 may approach very nearly the normal shape, but in practically 

 every case, it is more or less misshapen. Sometimes the new 

 portion seems to be developed mainly on one side; sometimes 

 the top of the eye presents, instead of a smooth convex surface, 

 a rough and wrinkled one. Sections of these eyes show several 

 very interesting points, but fail to prove with certainty that eyes 

 in any true sense are being regenerated, that is, eyes capable of 

 functioning as organs of sight. The condition of these regener- 

 ating eyes is made plain by an examination of Figs. 21-23, PI. 

 III. Fig. 21 shows a section through the central portion of an 

 eye from which the cornea had been removed forty-four days be- 

 fore. The points a and b mark the limits of the regenerated 

 cuticle. On the left side the line of union extends from a to o, 

 but on the right the break at b is abrupt. The newly developed 

 cuticle is very much less compact than the old cuticle, but is of 

 greater depth. In this instance the irregularity of the surface, of 

 which mention has been made, is caused by the cuticular growth. 

 The remnants of the old crystalline cones (cr.) are being cast off 

 by the new cuticle which is developing under them. The section 

 passes through the optic nerve (op.) and through the optic 

 ganglion (gl.). Just beneath the cuticle is seen a fairly com- 

 plete row of cells with well defined nuclei (hy), which I take to 

 be the hypodermis from which the new cuticle is being secreted. 



