462 Charles R. Stockard 



Stated in this form the two results appear to be identical." This 

 resemblance is quite true for the evidence furnished by Zeleny 

 but the more recent work fails to accord. In the larval lobster 

 and some ophiurans it is not true that "the more the material 

 removed the greater the rate of regeneration of the new part." 

 The influences exerted at different levels over the rate of regen- 

 eration cannot be identified with the influences due to diff^erent 

 degrees of injury. It must be recalled that Zeleny ('03 and '05) 

 claims that each appendage regenerates at a more rapid rate when 

 several are removed than when only one is amputated. This 

 has been shown not to be true for all animals but, on the other 

 hand, the total amount of tissue regenerated fiom several arm 

 stumps is greater than the amount from one even though the single 

 arm may be regenerating at a more rapid rate. The more mate- 

 rial removed up to a certain limit the greater will be the mass of 

 newly regenerated tissue in a given time, irrespective of whether 

 the greater amount of material is removed by cutting at a deeper 

 level or by amputating a larger number of appendages. The 

 statement in this form is supported by the present evidence. 



VII THE RELATION BETWEEN THE RATE AND AMOUNT OF REGEN- 

 ERATION AND THE PHYSICAL CONDITION OF THE ANIMAL BODY 



In the foregoing pages it has been repeatedly mentioned that 

 individuals regenerating several appendages are at the same time 

 either decreasing in actual body size or are increasing in size slower 

 than other individuals which are replacing fewer lost parts. It 

 seems expedient now to consider such cases collectively in order to 

 determine whether there is any actual tendency on the part of 

 regenerating tissue to appropriate nutriment at the expense of 

 the general body vigor. 



Emmel ('06) showed that the process of regeneration retarded 

 the growth of young lobsters sometimes as much as 24 per cent. 

 He demonstrated that the retardation was due to the process of 

 regeneration and not to mutilation or other causes: Since "the 

 average length of the molting period for those lobsters in which 

 the mutilations were not succeeded by the regeneration of the 



