498 Charles Zeleny 
General Result. The general result thus shows that successive 
removal brings about no change in tbe rate of regeneration. If 
the data indicate any change it is in the direction of increase and 
not of decrease. While the separate periods should strictly not be 
subjected to a cross comparison because of differences in the fac- 
tors involved it is interesting to note that a general average of the 
specific amounts in each table gives the advantage to the later 
regeneration, not only when all the individuals are included, but 
also when the exceptional individuals in each column are elimi- 
nated. Wh n the few exceptional individuals are removed from 
consideration the uniformity in specific amounts in the different 
cases is striking and the validity of the result is assured. 
In conclusion then the statement may be made that in young 
crayfish of the species Cambarus bartoni of thoracic lengths 
between 10.1 mm. and 13.9 mm., successiv 2 removal of a chela has 
little or no effect upon its rate of regeneration for the first three or 
four removals. If any change is indicated by the data, it is in the 
direction of increas: and not of decrease. 
4 The Chelz of the Gulf-weed Crab, Portunus sayi 
The method, data and results have been published in Tortugas 
vol. ii of the publications of the Carnegie Institution of Washing- 
ton.!8 A summary of the results is given here for comparison 
with the other groups. 
The method of procedure differs from that of the crayfish 
experiments. Individuals varying in size from 3 mm. to 15 mm. 
were collected and successive removals of the right chela were made 
in all the individuals. “These removals came in each case on the 
day after a molt. Apart from the age factor which was treated as 
described below the sources of error were treated in essentially 
the same manner as in the case of the crayfish (p. 495). For 
further details the original account should be consulted. 
It was found that in sixteen out of twenty cases the second regen- 
eration was greater than the first. In three the reverse was true 
18 Zeleny 708. 
