Regeneration in Compound Eyes of Crustacea 175 



ous with the inner surface of the cuticle covering the rest of the 

 eye. There are still masses of the injured inner tissues that have 

 been excluded by the formation of the crust clinging to its outer 

 surface. The old tissues in the interior of the eye stump have 

 shrunk back from the crust leaving a considerable space occupied 

 by coagulated plasma. The old cuticle and the matrix of the 

 crust both stain deeply either with orange G or acid fuchsin. 



No distinct cuticle can be recognized for several days, from six 

 to eight, after the operation. In the eyes of Palaemonetes that 

 have moulted seven or eight days after the infliction of the injury 

 a cuticle which corresponds approximately in thickness with the 

 cuticle covering the remainder of the eye has formed over the 

 wound. This new cuticle is much looser in texture than the old 

 cuticle. Regeneration does not take place so rapidly in crayfish as 

 in the marine forms examined so that a new cuticle is somewhat 

 longer in forming. Frequently a considerable space intervenes 

 between the overlying crust and the cuticle which has formed 

 beneath it. This is probably due to the recovery of the tissues of 

 the stump from their early swollen condition during which time 

 they were gorged with blood and occupied more than their normal 

 amount of space. It is not unusual to find considerable spaces 

 between different layers of the new cuticle as if a shrinking of the 

 tissues had taken place during the process of forming the new 

 layers of cuticle. The shrinking of the interior tissues without 

 doubt also accounts in part for the folds and wrinkles which 

 often appear in the cuticle over the wound. 



The secretion of the new cuticle which grows over the wounded 

 surface begins some little distance back from the cut edges of the 

 old cuticle and is continuous with its inner layers. Fig. 47 is a 

 semidiagrammatic representation of the relation of the old and the 

 new cuticle and the exclusion of the broken down tissue by the 

 development of the new cuticle beneath it. Only eight nuclei 

 appeared beneath the new cuticle in the section as shown in Fig. 

 47. This figure is taken from an eye that had been injured by 

 tearing through the cuticle with a needle. Reference to the figure 

 shows that very little of the old cuticle had been removed. Fig. 50 

 shows part of a section near the edge of the wound, Fig. 51 part of a 



