538 Charles Zeleny 
14 The Chele of the Shrimp, Palemonetes vulgaris (Stimp) 
Nos. 1806-1861” 
The object of the experiment was the comparison of the rate 
of regeneration of a single chela when it alone is removed with 
the rate of the two chelz when both are removed. 
Fifty-six shrimps were collected at Wood’s Hole on September 
2, 1906. Eighteen of these were “control”? specimens without 
an operation, twenty had both chele removed and eighteen had 
one chela removed, the right in nine and the left in the other 
nine. ‘The operations were made on September 2 and all animals 
were killed on September 10 giving a regeneration interval of 
eight days. 
Only sixteen out of the thirty-seven available operated shrimps 
molted during the eight days of the experiment. Eight of these 
had the greater and eight the lesser injury. All thirty-seven 
individuals are however available for the comparison of rates of 
regeneration because in Palamonetes vulgaris the new chela grows 
out directly and is not curled up in a chitinous sac as in the 
crabs. It is therefore unnecessary to wait for the molt. As a 
matter of fact the data show that the molted individuals are not 
necessarily the ones with the greatest length of regenerating chelz. 
The data are given in Tables 8, 9, 10 and 11. Table 8 gives 
the data for the shrimps in which the left chela alone was removed. 
Table g gives the data for those in which the right chela alone 
was removed. Table 10 gives the corresponding data for the 
ones in which both chela were removed. In Table 11 the specific 
amounts of regeneration are compared. ‘They are arranged in 
order of magnitude beginning with the lowest, except the left 
chela in shrimps with both chelz removed and regenerating. In 
these last the left chela are put opposite the right ones of the 
same individuals. Since the period of regeneration is eight days 
in every case the specific rates are comparable in the same way. 
In individuals with both chela removed (nineteen cases) the 
average specific amount of regeneration of the left chela is 0.282 
*I am indebted to the acting director of Wood’s Holl Marine Biological Laboratory, Professor 
Frank R. Lillie, for the use of a room during August and September, 1906. 
. 
