SOME INTERNAL FACTORS CONCERNED WITH THE REGENERATION 

 OF THE CHEL/E OF THE GULF-WEED CRAB (PORTUNUS SAYF). 



By Charles Zeleny. 



INTRODUCTION AND GENERAL STATEMENT OF RESULTS. 



The primary object of the experiments described in the present paper 

 was twofold: The quantitative determination (i) of the effect of successive 

 removal of an organ upon its power to regenerate and (2) of the character of 

 the changes, if any, produced in the uninjured parts of the animal by such 

 removals. In connection with the first problem it was found necessary to 

 determine as preliminary steps the common relations in tiie amount of 

 regeneration, the length of the molting period, and the size or age of the 

 animal. Since these are points of independent interest they are treated 

 in separate sections at the beginning of the paper. The second problem 

 was studied by a comparison of the character of the left chela in normal 

 individuals with its character in individuals having a removed and regen- 

 erating right chela. 



It was found that the length of the molting period is but slightly corre- 

 lated with the amount of regeneration of the right chela and the size of 

 the animal. Thus if all operations are made on the day after a molt the 

 length of time elapsing before the next molt has very little to do with the 

 amount of regeneration which takes place during the period. Likewise, 

 animals of a size, which in general are probably of the same age, do not 

 have the same length of molting period. On the other hand, there is a very 

 close correlation between the size of the animal and the amount of regen- 

 eration taking place during a molting period. 



On the basis of these results the molting period is taken as the unit in the 

 determination of the amounts of successive, regenerations. It is found in 

 general that in individual crabs the third regeneration of the right chela is 

 greater than the second, and the second is greater than the first. Since the 

 animals are increasing in size and age during the course of the experiment, 

 and since this may be sufficient to explain the increase in amount of regen- 



'The experiments were performed at the Marine Biological Laboratory of the 

 Carnegie Institution of Washington at Tortugas, Florida. I am indebted to the offi- 

 cers of the Carnegie Institution for the privileges of the laboratory during June and 

 July, 1906. I wish especially to thank the Director, Dr. A. G. Mayer, for valuable 

 suggestions and for many other courtesies without which the experiments could not 

 have been successfully completed. The material obtained at Tortugas was measured 

 and studied and the data were tabulated at the zoological laboratory of Indiana Uni- 

 versity during the school year 1906-1907. The present paper is listed as No. 87 of the 

 contributions from the Zoological Laboratory of Indiana L^niversity. 



105 



