62 



The Relation of the Degree of Injury to the Rate of 

 Regeneration and the Moulting Period in the Gammarus. 



Mary T. IIarman. 



INTKODUCTION. 



Ill 1!)U5 in some experiments on tlie craytisli, Zeleny found that in 

 the series of crayfish with the greater degree of injury each eliela regen- 

 erated more rapidly than tlie cliela in the series with the lesser degree 

 of injury. He also found that the members of the series with the greater 

 degree of injury moulted more rapidly than the members of the series 

 with the lesser degree of injury. In 1900, in some experiments on the 

 lobster, Emmel found that in the series of lobsters with the lesser degree 

 of injury the regeneration was more rapid than in the series with the 

 greater degree of injury and the members of the series with the lesser 

 degree of injury moulted more rn])i(llj' than the members of the series 

 with the greater degi'ee of injury. 



During the summer of 1905 at the Indiana University Biological Sta- 

 tion at Winona Lake, Indiana, the author tried some experiments on gam- 

 marus. The death rate was so great that the number of animals of each 

 series that survived was only six, and those showed little difference in 

 the per cent, of regeneration. The series with the lesser degree of injury 

 showed a little greater per cent, of regeneration than the series with the 

 greater degree of injury. No observations were made on the relation of 

 the degree of injury to the moulting period. During the summer of 1907 

 at the .same place the author tried some similar experiments on the same 

 gammarus. The death rate was again great and the difference in the 

 per cent, of regeneration was less than in the first experiments. The degree 

 of injury niad*> very little difference in tlie lengni of the moulting ])eriod. 



METHOD. 



The gammarus used in these experiments were obtained from Winona 

 Lake, Indiana, near tlie mouth of Cherry Creek. On .Inly 9. lOO.'i. about 

 (wo hundred gammarus were taken from the lake m-ai' (he mouth of 



