1 76 Mary Isabelle Steele 



section near the center of the wound. Both figures show the 

 distribution of the hypodermal nuclei beneath the new cuticle that 

 had formed over the cut surface of the eye of a Palaemonetes ten 

 days after the operation. Examination of Figs. 47, 51 will show 

 that a new cuticle may be secreted before a complete hypodermis 

 can be recognized. 



Recently hatched Cambarus gracilis, 12 to 15 mm. in length 

 had eyes injured by tearing through the cornea with a sterilized 

 needle. The eyes operated upon in this manner were fixed at 

 different times, varying from eleven to thirty-five days. All of 

 the eyes, however, were fixed before a moult had taken place. In 

 this way it was possible to determine the precise position of the 

 original injury. Sections of such eyes show one point conclusively, 

 at least for Cambarus gracilis. That is that the proliferation of 

 new cells begins from the hypodermis immediately surrounding 

 the rent. From the edges of this proliferating center new cells 

 push out to replace the cells that were removed or that have broken 

 down. Previous observations made upon the regeneration of the 

 eye in crayfish (Steele '04) indicate that crayfish probably do not 

 regenerate a functional eye. It appears, however, that the prelim- 

 inary regenerative processes are essentially the same in crayfish as 

 in the other forms examined. 



It is frequently the case that a much greater proportion of the 

 soft inner tissues are destroyed than of the outer cornea or the 

 hypodermal layer beneath it. When the cut is made the retinulae 

 and the lower ends of the cone cells press out of the wound and 

 leave the outer ends of the cones and the hypodermis practically 

 undisturbed. Such a condition is particularly noticeable in eyes 

 that were operated upon by tearing the cornea with a needle. In 

 such cases the hypodermal cells in situ secrete the new cuticle. 

 This cuticle is, however, without corneal facets, a fact which 

 shows that while the operation neither removed nor caused the 

 disintegration of the hypodermal cells it still affected their activity 

 to such an extent that they no longer function in their usual 

 specialized manner. They now function as the ordinary hypo- 

 dermal cells over the general surface of the body. 



Sections frequently show a morphological transformation of the 



