298 CHARLES ALBERT SHULL. 



not until recently has a critical study of it been attempted. A 

 review of the earlier literature relating to regeneration in the 

 Decapoda has been given by Miss Steele, '04 ; it is necessary, 

 therefore, to mention only a few of the later papers upon whose 

 results my own observations have some bearing. 



Morgan, '98, desiring to test Weismann's hypothesis, that re- 

 generation is an adaptation, experimented with Eupagnrus longi- 

 carpns to determine what relation, if any, existed between the 

 power of regeneration and liability to injury. Because the her- 

 mit crab lives in shells where the abdominal appendages are pro- 

 tected from injury, whereas the thoracic appendages are not so 

 protected, these two series of organs were chosen for this experi- 

 ment. He came to the general conclusion that no such relation 

 existed, and further supported this view by a second paper in 

 1900. The latter paper was based upon experiments in which 

 the thoracic appendages were removed at unusual levels. 



He found in the course of his experiments that the ab- 

 dominal appendages of Eupagurns did not regenerate readily, 

 although slight regenerative power existed. He suggested that 

 this rarity of regeneration "may be connected in some way with 

 the amount of food supply brought to the region from which 

 they arise." 



Miss Steele, '04, experimenting with Cambarus virilis and C. 

 gracilis has obtained results similar to Morgan's. She says, 

 speaking of the swimmerets : "I have found none to regenerate 

 except the first pair in the male. ... In the case of the other 

 abdominal appendages except the sixth pair, regeneration, if it 

 does take place, is very slow in beginning." 



Emmel, '04, reported the observation of regeneration in the 

 first appendages of the lobster. He experimented with the other 

 appendages and says : " In experiments with the other four pairs 

 of abdominal appendages or swimmerets, positive results were 

 obtained in the second and third pairs, and it seems safe to say 

 that all the swimmerets will regenerate." 



Haseman, '07, mentions the regeneration of swimmerets in C. 

 propinquus, giving figures showing the progress of differentiation, 

 but he does not mention the fact that the regeneration of these 

 appendages was considered doubtful. 



