iio Papers from the Marine Biological Laboratory at Tortugas. 



regenerations. An examination of these tables shows at once that there is 

 no evident difference between tlie first and second regenerations when the 

 size-difference is eliminated. For equal cephalo-thoracic lengths the amount 

 of the first regeneration is approximately equal to that of the second. The 

 average specific amount for the first regeneration is 0.791 with 66 cases 

 and for the second regeneration 0.789 with 25 cases. The difference be- 

 tween the two is well within the limit of probable error. Therefore the 

 successive removal of the right chela does not retard nor accelerate the 

 power to regenerate. 



EFFECT OF REMOVAL OF RIGHT CHEL.A. UPON CONDITION OF LEFT CHEL.\. 



Table 15 gives the cephalo-thoracic lengths, the left and right chela- 

 lengths, and the specific lengths of the chela for 165 unoperated indi- 

 viduals.' The individuals are arranged in order of cephalo-thoracic length. 

 The specific length of a left chela is the left chela-length divided by the 

 cephalo-thoracic length. Table iic shows the correlation between the left 

 chela and the cephalo-thoracic length in the same individuals. The dotted 

 line is the line of average specific chela-length ; that is, the line along which 

 all the data would be arranged if the specific lengths were alike for all sizes. 

 Tables 16 and iid give the corresponding data for individuals which have 

 regenerated a right chela for the first time and tables 17 and 18 for second 

 regeneration cases. 



Tables 15 and iic show that in unoperated individuals the left chela 

 length is closely correlated with the cephalo-thoracic length. The average 

 specific length of the left chela is 0.982, but an examination of the tables 

 shows that smaller individuals have comparatively smaller chelae than the 

 larger ones, a fact which has already been referred to above. 



Tables 16 and iid for first-regeneration cases and tables 17 and 18 for 

 second-regeneration cases show that there is no evident dift'erence between 

 the lengths of the left chela in these individuals and those in unoperated 

 individuals. The left chela is not influenced by the removal and regenera- 

 tion of the right chela. This is readily seen when the co5rdinate tables 

 are superposed. Furthermore, the average specific length for first-regener- 

 ation cases is 0.993 and for second-regeneration cases i.oii as against 

 0.982 for the imoperated cases. This progressive increase for the regener- 

 ation cases is, however, fully accounted for by the greater average cephalo- 

 thoracic length of the regeneration cases as compared with the unoperated 

 ones and by the fact that the specific amount of chela-length increases with 

 the size of the individual. 



^Relative sizes of the right and left chelee in uninjured individuals. — In is inter- 

 esting to note that the right chela is, on the whole, larger than the left. Of the 165 

 individuals whose chela-lengths are tabulated the two chelff are of equal size in 49, 

 the left chela is greater than the right in 19, and the right is greater than the left 

 in 97. The average length of the propodite of the left chela is 5.77 mm. and of the 

 right chela 5.84 mm., an advantage of 0.07 mm. in favor of the right chela. 



