g6 Charles Zeleny. 



Evidently the differences between the retarding influences of the 

 three members are greatest near the beginning of the experiments, 

 I. e., immediately after the operation, and gradually decrease as we 

 go away from this point. Correspondingly, the results show a 

 greater comparative difference in regenerated material at the end 

 of the first moult than at the end of the second moult. 



This result agrees very well with the experiments on the fiddler- 

 crab Gelasimus (p. 8i) and on the brittle-star Ophioglypha, 



(P-7)- 



As moulting involves not only an increase in bulk of the animal 

 but also a complicated degree of differentiation of materials before 

 it can be accomplished, we may likewise compare the acceleration 

 of moulting in Alpheus and Gelasimus with the acceleration of the 

 rate of differentiation of the opercula in Apomatus when the pos- 

 terior region of the body is also removed as compared with the 

 cases where this region is uninjured. 



General Discussion. 



The following discussion does not serve as a summary of the 

 data of the preceding sections. For this the reader must be 

 referred to the summaries of the individual sections which are 

 complete entities in themselves. It is the writer's purpose in the 

 general discussion to show the manner in which the various data, 

 at first sight seeming to have little in common, can be brought 

 under a common point of view. 



In the introduction it was stated that the standpoint of the 

 present paper would be the consideration of the organism as a 

 system made up of mutually interacting parts, the relations of 

 which were to be studied by noting the disturbances produced as a 

 result of the removal of one or more of the parts. 



In the paper on the dimensional relations of the members of 

 compound leaves the relations of the parts of a system were studied 

 in which the removal of one member was not followed by its 

 regeneration but resulted in changes in size and position of the 

 remainder. The chief reactions were the following: In the five- 

 leaved forms in which an asymmetrically placed leaflet was 

 removed the other four leaflets tended to rotate to a position such 

 that the new system was a symmetrical four-leaved one. Like- 



