THE RELATION OF THE DEGREE OF INJURY TO THE 

 RATE OF REGENERATION.! 



BY 



CHARLES ZELENY. 

 I. INTRODUCTION. 



It is a common beliei that an increase in the degree of injury 

 to an animal lowers its vitality and thereby diminishes its capacity 

 for repairing sustained injuries. It is certainly true that if an 

 animal is mutilated to a degree so great that it can barely survive 

 the operation a rapid rate of regeneration of the parts is not to be 

 expected, though there is little direct evidence in favor of this 

 statement. The general view that injury to an increased number 

 of organs implies a decrease in the rate of regeneration of each, 

 however apparent it may seem at first sight, needs further exam- 

 ination. The data to be given below prove very conclusively 

 that the view is an erroneous one, for it is shown that the animal 

 with the greater number of removed parts regenerates each part 

 7nore rapidly than does the one with the lesser number of removed 

 parts. 



In the summer of 1902 the author performed some experiments 

 on the fiddler crab, Gelasimus, which showed that when both 

 chelae are removed each of the regenerating buds grows more 

 rapidly than does the single one in the cases where only one chela 

 is removed. The rate of moulting of the animals is likewise 

 greater in the individuals of the former group than in those of the 

 latter. The difference was naturally more plainly made out in 

 the female individuals which have chelae of equal size than in the 

 male individuals which have chelae of unequal size. The results 

 are, however, not as conclusive as they might have been, had the 

 number of individuals been greater and had a greater length of 

 time been available for the experiment. 



'Contribution from the Zoological Laboratory of Indiana University, No. 



