Regeneration in Compound Eyes of Crustacea 237 



discovered that after the larger chela of Alpheus had been removed, 

 cutting the nerve in the smaller one prevented it from growing 

 into the form of the larger one when, however, the large chela had 

 been removed and the nerve in the small one left intact, the small 

 chela developed into the form of the large one. It has been noted 

 above that Miss Reed found she could obtain the regeneration of 

 the double chelae. The experiments of Schaper ('98), Harrison 

 ('03), Barfurth ('01), Goldstein ('04) and others have shown that 

 the early stages of embryonic development and of regeneration 

 are apparently independent of the nervous system. But the same 

 experiments have also shown that the later stages of growth and 

 differentiation are very largely influenced by the part of the nervous 

 system which normally innervates the regenerating or developing 

 parts; other instances might be mentioned but a sufficient number 

 have been given to convince one that in very many instances there 

 is an important connection between the part of the nervous system 

 immediately concerned and the regeneration of the other tissues 

 and structures. 



VII Regeneration after Splitting the Eye Longitu- 

 dinally 



Several series of Palaemonetes were operated upon by having 

 the eye split longitudinally (Table i). Although in the regener- 

 ation of any part of the eye the new tissue is derived from the 

 hypodermis the results obtained from the experiment of splitting 

 the eye seem to indicate that injury to the optic ganglion is of 

 great importance. In many cases at least splitting the eye could 

 not have resulted in serious injury to the hypodermis yet in no case 

 did regeneration follow if the optic ganglion had been injured. 

 Whether or not regeneration followed the operation apparently 

 depended upon the depth of the split. If the split extended 

 through the ommatidial portion only and the optic ganglion 

 remained uninjured, the ommatidial portion degenerated and new 

 ommatidia w^ere in some cases regenerated. On the other hand, 

 if the split extended into the optic ganglion the whole ommatidial 

 portion and the whole or part of the optic ganglion degenerated. 



