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THE AMEBIC AN NATURALIST [Vol. XLII 



the edge or tip of a fin the cut is made the slower will be the 

 rate of growth of the new tissue. 



Repeated amputation, or removal of regenerating buds, con- 

 tinues to accelerate the moulting process. Zeleny has shown 

 in Cassiopea, a jelly-fish, that repeated operation also hastens 

 the rate of regeneration. New tissue grows faster from a cut 

 surface that has previously regenerated tissue than from a newly 

 cut surface that has not before regenerated. 



Zuelzer finds, like Emmel, that the moult ing time is unaffected, 

 or she believes at times hastened, in those cases where regenera- 

 tion fails to follow the amputation of appendages. The reason 

 for this she thinks may be that the animal with fewer append- 

 ages has a smaller body mass and. therefore, more food to 

 use in normal growth, particularly when none of this food is 

 used to form regenerating tissue. Thus Emmel's lobsters which 

 failed to regenerate moulted more rapidly than regenerating 

 ones. When one considers, however, the apparent unimportance 

 of food-supply on regeneration phenomena as shown by Morgan 

 he becomes disinclined to accept Zuelzer's explanation. 



In a general way Zuelzer agrees with Zeleny in that regen- 

 eration hastens the moulting process. It is interesting to note 

 that both of these workers have used adult Crustacea while 

 Emmel's experiments were made upon larval or young lobsters 

 and gave opposite results. A possible reconciliation of the re- 

 sults may be as follows: The young lobsters, like most young 

 animals, are growing at a maximum rate: all available energy 

 is being used in growth. When such animals are injured they 

 receive a "set-back" since some of their energy must now be 

 diverted in order to repair the injury. Emmel showed that 

 the process of regeneration retarded the rate of growth of these 

 lobsters sometimes more than twenty-four per cent., but when 

 the injury was not repaired growth or moulting was not re- 

 tarded. Adult animals, on the other hand, are not living up 

 to their maximum possibilities; they are in an apparent state of 

 reserve until the removal of an appendage or other injury 

 excites them to new activities and regenerative growth begins. 

 During regeneration the animal may be said to be in a con- 

 dition of newly stimulated growth and all growth activities are 

 probably influenced. One may predict that if .similar regen- 

 eration experiments be tried on the adult lobster the results 

 will agree with those obtained on adult crayfish and Asellus. 



C. R. Stockard. 



