28 UNIVERSITY OF MISSOURI STUDIES [3l6 



Fig. 23 shows still another abnormality in the growth and 

 development of the cuticle. Here only the calcified cuticle and 

 underlying hypodermis are shown. The internal structure is 

 practically identical with that of the preceding figures. In this 

 case only one side of the corneal surface had been removed; an 

 oblique cut passing along the line ab removed perhaps a fourth 

 of it. The regenerating tissues are but ten days old. The hy- 

 podermis is a continuous layer beneath both old and new cuticle. 

 On the right the cuticle has grown inwards a considerable dis- 

 tance ; or probably it would be more correct to suppose that the 

 cuticle had formed from b over to a before an appreciable 

 amount of tissue had been developed; then, the internal tissues 

 growing rapidly forced the hypodermis and cuticle back, so that 

 an apparent invagination of the cuticle was produced. There 

 have been, it seems, two periods of activity in the secretion of the 

 new cuticle. The outer, older portion (n. c.) seems to be more 

 compact than the younger, inner part (n. c). The inner layers of 

 the new cuticle, together with the hypodermis form a continuous 

 structure beneath both the old cuticle and the older part of the 

 new. From a to d are what appear to be some remnants of the 

 old corneal facets which are being thrown off. 



Fig. 24, PI. Ill, is a section of an eye that had been oper- 

 ated upon forty-four days before. Internally it shows the same 

 structures as have been described in previous figures. However, 

 this section is taken eccentrically and shows none of the optic 

 nerve and but little of the optic ganglion. The only new feature 

 in the section is the conspicuous difference between the old and 

 new cuticle. The old cuticle (o. c.) shows many more lamellae 

 and those lamellae much more compactly arranged than in the 

 new cuticle (n. c). On the right side, the union of the old and 

 new cuticle at a is rough and uneven and less perfect than at b. 



In only one instance have I ever found any indication of 



