Rate of Regeneration. 



349 



lesser degree of injury. Likewise the members of the series with 

 the greater injury moult more rapidly than those of the series with 

 the lesser injury. 



2. METHOD. 



The specimens used in the experiment were collected in a small 

 brook about a mile and a half from the Indiana University campus 

 at Bloomington. They were all taken from a part of the brook 

 not exceeding two hundred feet in length and it is probable that 

 the general conditions of the environment to which thev had been 

 subjected were similar for all up to the time of capture on October 

 II, 1904. About 150 specimens were obtained at this time and 



Fig. I. 



Diagram showing a bottle as arranged for the reception of one of the crayfish used in the experi- 

 ment. See text description on page 350. 



from this lot 77 of the individuals ranging in thoracic length from 

 ten to twenty millimeters were selected and divided into two groups 

 which were made as nearly as possible equivalent in point of size 

 of individuals. In series A which comprised 36 individuals the 

 right chela was removed at its breaking joint. In series B which 

 comprised 41 individuals the two chelae and the last two pairs of 

 walking legs were removed in a similar manner. Except for this 

 difference in the degree of injury the two series were consistently 

 treated alike throughout the whole course of the experiment. 

 The series with the greater injury (Series B) was purposely given 

 the greater number of individuals in anticipation of a greater 

 death rate in this series. Both males and females were included 

 in each series. 



