REGENERATION AND NEOTENY. 



By EDUARD UHLENHUTH. 



{From the Laboratories of The Rockefeller Institute for Medical Research.) 



(Received for publication, January 29, 1920.) 



According to Kamerer, it is possible to prevent metamorphosis in 

 the caudate amphibians by amputation of the legs or tails of the 

 larvae. In my attempts to produce neoteny in the larvae of salaman- 

 ders, however, Kammerer's method has been tried without success, 

 my experiments failing completely to confirm Kammerer's positive 

 statements with regard to the effectiveness of the method. 



DumeriP observed that among several larvae of Amby stoma 

 tigrinum, which were the offspring of neotenous animals (axolotls), 

 only those metamorphosed which had been deprived by their comrades 

 of legs and part of their tails. He believed, therefore, in contradistinc- 

 tion to Kammerer, that regeneration may induce metamorphosis in 

 larvae which without regeneration would become neotenous. Later, 

 however, he observed that larvae of the same lot, which had not been 

 mutilated, also metamorphosed; hence he was finally convinced that 

 regeneration had nothing to do with metamorphosis of the larvae. 



Kammerer^ experimented not only on the larvae of caudate 

 amphibians {Triton cristatus and Triton alpestris) , but also on those of 

 Salientia. He amputated the limbs as well as the tail. He concluded 

 from his experiments that 



"Injuries of any sort effect metamorphosis in directly opposite ways in Urodela 

 and Anura as demonstrated with greatest certainty in the experiments. While 

 in the salamander larvae neoteny is brought about without the slightest difficvdty, 

 if only one limb or a piece of the tail is removed, the same procedure induces a 

 rapid appearance of the transformation symptoms in the tadpole."^ 



1 Dumeril, A., Ann. Sc. Nat. Zool, 1867, vii, 229. 



^ Kammerer, P., Arch. Entwcklngsmechn. Organ., 1905, xix, 148. 



^ Kammerer, P., Arch. Entwcklngsmechn. Organ., 1905, xix, 176. 



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