The Transformation of the Mexican Axolotl. 565 



year (1875) I must abandon my scheme, and this 

 can be done the more readily because, for the 

 theoretical consideration of the facts, it is imma- 

 terial whether all or only nearly all the Axolotls 

 could have been compelled to undergo transforma- 

 tion. I must not, however, omit to mention that 

 Herr Gehrig, the curator of our Zoological 

 Museum, bred a considerable number of larvae 

 from the same brood as that with which Fraulein 

 v. Chauvin experimented, and that of these larvae 

 six lived over the winter "without undergoing meta- 

 morphosis. They were always kept in deep water 

 and thus furnished the converse experiment to 

 those recorded above ; they further prove that this 

 whole brood did not have a previous tendency to 

 undergo metamorphosis. 



If these new facts are to be made use of to 

 explain the nature of this extraordinary process of 

 transformation in accordance with our present 

 conception, the data already known must in the 

 first place be called to our aid. 



It has first to be established that Siredon 

 Mexicanus never, as far as we know, undergoes 

 metamorphosis in its native country. This Amphi- 

 bian is there only known in the Siredon form, a 

 statement which I have taken from De Saussure, 1 

 who has himself observed the Axolotl in the Mexi- 

 can lakes. This naturalist never found a single 



1 Verhandl. Schweiz. Naturforsch. fiesellschaft. Einsiedeln, 

 1868. 



