164 Mary Isahelle Steele 



I Introduction 



The regeneration of the Crustacean compound eye has been 

 made a subject of observation bv a number of investigators. But 

 for the most part end results alone have been described. Very 

 few details of the processes involved in regeneration have been 

 given. To give an accurate description of the histogenesis of the 

 regenerated structures is the chief aim of this paper in the belief 

 that it will contribute something toward a more accurate under- 

 standing of the more general problem of regeneration. 



The problem has separated itself into three main divisions: 

 first, the regeneration of a functional eye; second, a search for the 

 causes of no regeneration and abnormal regeneration, and third, 

 obsers'ations upon the heteromorphic regeneration which may 

 follow the removal of the entire eye. 



Herbst ('96, '00) and Morgan ('98) have made the principal 

 observations upon the regeneration of the Crustacean compound 

 eye. But so far as the particular phases dealt with in this paper 

 are concerned Herbst's descriptions are not sufficiently detailed 

 to be of especial assistance in this work. Herbst's observations 

 upon the regenerated heteromorphic structures are somewhat 

 more extensive and in some respects furnish an excellent basis for 

 comparison with the results to be discussed in this paper. For 

 the most part, however, where results have been compared with 

 the work of others the comparison is made between the regenera- 

 tive and embryonic development and between normal and regen- 

 erated structures. 



The terminology employed is in great part that used by Parker 

 ('91) in his work upon the compound eyes of Crustacea, it being 

 the terminology in most general use. A few minor deviations 

 have been made but no wholly new terms have been introduced. 



The following plan has been followed in this paper. First, a 

 brief description of the normal adult eye is given to furnish a basis 

 for comparison. This is followed bv a description of the prepara- 

 tory regenerative processes which in reality constitutes one of the 

 most important phases of the subject. Then the regenerative 

 processes proper are described under the three main divisions 

 already suggested. 



