Rcgenei-ation of the Chela of the Gulf-weed Crab. 109 



This increase is shown for the left chela in table lie. Here the dotted 

 line is the line along which all the chela measurements would come if all 

 individuals had the same specific length of the left chela. As before, it is 

 seen that the larger individuals have proportionately a larger chela than 

 the smaller ones; that is, the specific length of the chela is greater in the 

 former than in the latter. 



COMPARISON OF THE REGENERATIONS OF THE RIGHT CHELA AFTER 

 SUCCESSIVE INJURY. 



(a) The successive regenerations in single individuals. — After the re- 

 moval of all the possible sources of error that could be found 21 valid cases 

 of successive regeneration remain. Table 13 gives these cases arranged in 

 order of the lengths of the original right chelae. Table 14 shows the same 

 cases on coordinate paper with the original lengths of the chelae represented 

 by the abscissae and the amounts of regeneration by the ordinates. The 

 dotted line is the line of equal length of regenerated and original chelae. A 

 third regeneration was obtained in only two of the 21 cases. In one of 

 these the first regeneration record is missing. Apart from this the third 

 regeneration is greater than either the first or the second regeneration. In 

 the 20 cases in which tlie first and second regenerations can be compared the 

 two are alike in i individual, the first is greater than the second in 3, and 

 the second is greater than the first in 16. Thus, in the great majority of 

 cases, the rate of regeneration increases with the successive removal of the 

 right chela. This result, however, does not take into account the possibility 

 of change in the ability to regenerate due to an increase in size or age. The 

 individual power to regenerate may be changing during the course of the 

 experiment regardless of the removal or non-removal of an appendage. In 

 the following section an attempt is made to eliminate this source of error 

 and to determine whether the successive removal itself has any influence. 



{b) A comparison of the first and second regenerations of the right 

 chela in individuals of the same size or age. — Tables 10, 11 a, and 12 have 

 shown that with an increase in size there is a proportionate increase in the 

 amount of regeneration of the right chela. Therefore the difiference be- 

 tween the finst and second regenerations shown in the last section may be 

 due merely to this factor. A comparison of individuals of similar size is 

 made for the first and second regenerations in tables 10 and iin. In table 10 

 individuals of equal size are placed as nearly as possible opposite each other, 

 so that a direct comparison of the amounts of regeneration may be made. 

 In table iib the abscissae represent the cephalo-thoracic lengths and the ordi- 

 nates the chela lengths. The first regenerations are shown by crosses and 

 the second regenerations by circles. The dotted line is the line along which 

 all the marks would be arranged if the specific amounts of regeneration 

 were the same for all sizes of individuals and equal for the first and second 



