114 Papers from the Marine Biological Laboratory at Tortugas. 



does not begin to function as such until after the molt succeeding an 

 operation. The whole chela function during this period is, therefore, carried 

 on by the left chela, which, according to a common theory of hypertrophy, 

 ought to increase in size because of this increase in function. Since it does 

 not, it seems probable, if growth is dependent upon the presence of certain 

 formative or food substances, that the excess of these is directed to the re- 

 generating appendage. The conclusion may thus be reached that the regener- 

 ating appendage uses in its growth the same kind of material as that used 

 by a growing uninjured chela. Furthermore, it follows that the distribution 

 of this material is not necessarily determined solely by the exercise of its 

 typical function by the organ in question. 



This statement is offered merely as a suggestion, because the data of 

 the present study are not sufficient for a comprehensive discussion. The 

 method with proper control gives promise of considerable value in obtain- 

 ing an understanding of the internal factors involved in hypertrophy and 

 regeneration. 



SUMMARY. 



(i) Individuals of Portumis sayi with a cephalo-thoracic length between 

 3.9 and 14.5 mm. show but a slight correlation between the length of the 

 molting period and the size or age of the animal. 



(2) The amount of regeneration of the right chela between the same 

 limits of size is likewise but slightly correlated with the length of the molt- 

 ing period, but is very closely correlated with the size of the animal. 



(3) The specific amount of regeneration of the right chela increases 

 slightly with increase in size or age of the animal. 



(4) The specific length of the left chela in uuinjiu-ed individuals in- 

 creases slightly with increase in size or age of the animal. 



(5) The proportion between the amount of regeneration of a chela and 

 the length of the chela in uninjured individuals of the same size is a con- 

 stant uninfluenced by the size of the animal. 



(6) In single individuals the third regeneration is greater than the 

 second and the second is greater than the first. 



(7) When the correction for change in the power of regeneration with 

 size or age is made it is found that successive removal neither retards nor 

 accelerates the regeneration of the right chela. 



(8) The right chela is slightly larger than the left in a great majority of 

 the individuals. 



(9) The removal and regeneration of the right chela produces no change 

 in the growth of the uninjured left chela. 



