Effect of Successive Removal upon Regeneration 499 
and in one the two were equal. In the two cases with a third 
regeneration the third was greater than the second. ‘This state- 
ment, however, does not consider a possible change with age. 
When the age factor is eliminated the difference disappears. 
In individuals of equal cephalo-thoracic length the amount of the 
first regeneration is approximately equal to that of the second. 
The average specific amount of the first regeneration 1s 0.791 for 
sixty-six cases and of the second regeneration 0.789 for twenty-five 
cases. ‘The difference between the two is well within the limit of 
probable error. ‘Therefore it may be concluded that successive 
removal of the right chela in the gulf-weed crab nether retards nor 
accelerates its power of regenerat‘on. 
5 he Chelze of the Gulf-weed Shrimp, Palamon tenuicornis 
Method. ‘Twenty-four gulf-weed shrimps were collected on 
June 16, 1906, at Tortugas. “They were put into individual dishes 
and fed every day on pieces of a small fish, Atherina. The opera- 
tions consisted of the removal of a single chela (the right in all 
‘except No. 1442) on the day after a molt. The general mode of 
procedure agrees closely with that for the gulf-weed crab.1® How- 
ever, on account of the small number of individuals used, it was 
not possible to entirely eliminate the age factor. Accordingly 
the comparisons as given here are between the successive regener- 
ations of a chela within single individuals and are not valid in a 
general discussion of the effect of successive removal as a distinct: 
factor. 
Data. Regeneration was approximatelycompleted within a single 
molting period. Cases which ran for two molting periods or which 
had an additional injury are indicated by an asterisk (*) in Table 
13. The measurements of the chelz are the lengths in milli- 
meters of the propodites. ‘The thoracic length is the post-spinous 
thoracic length. ‘The specific amount of the last regeneration is 
the regenerated chela length divided by the final thoracic length or 
the amount of regeneration per unit of thoracic length. 
Results. An examination of Table 13 shows that in individual 
shrimps with two exceptions there is a gradual decrease in the 
19 Zeleny ’o8. 
