CORRESPONDENCE. 



To the Editor of the American Naturalist: 



Sir:—\xx The American Naturalist June, 1903, p. 385, Mr. J. H. 

 Powers says that the metamorphosis of Ambly stoma tigrinum is due 

 to nutritive causes. Be pleased to rectify that the same conclusion 

 was published by me August, 1899, in La Naturaleza, Ser. ii, F. iii, 

 p. 369. The title of my notes is as follows : 



"El Ajolote sufre la metamorfosis general en la clase de los 

 batracios, par aumento de nutricion y no por cambia de medio." 



Experiments and observations in the latter where Amblystoma was 

 first observed, show that metamorphosis is very slow in artificial 

 or natural conditions, if the animals are feeble, and very rapid in the 

 best conditions of nutrition as in deep waters of Xochimilco, a lake 

 that never becomes dry. 



The dogmatical views on adaptation of Amblystoma are wrong 

 and the paper of Mr. Powers has only attested my own published 



I am very respectfully yours, 



A. L. Herrera. 



Mexico, Oct. 12, 1903. 



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