62 



The Relation of the Degkee of Injury to the Rate of 

 Regeneration and the Moulting Period in the Gammarus. 



Mary T. Harm an. 



INTKODTXTION. 



In 1905 iu some experiments on the cnijHsh. Zeleuy found that in 

 the series of eraytish with the greater degree of injury each chehi I'egen- 

 erated more rapidly than the chehi in the series witli the lesser degree 

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

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

 with the lesser degree of injury. In lOOCt. iu 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 rajiidly tlian the members of the series 

 with the greater degree of injury. 



During the summer of 190."> at the Indiana I'niversity 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 degi-ee 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 autlior tried some similar experiments on the same 

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

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

 of injury made very little difference in the length of the moulting period. 



METHOD. 



The gannnarus used in these experiments were obtained from Winona 

 Lake. Indiana, near the mouth of Cherry Creek. On July 9, 190."i, about 

 two hundred gammarus were taken from the lake near the mouth of 



