The Transformation of the Mexican Axolotl. 563 



the gills were much shrivelled, but the aquatic tail 

 and dorsal crest were unchanged. The crest may, 

 however, also disappear, and the tail become 

 shortened without these changes being due to a 

 transformation into Amblystoma, as will be shown 

 further on. 



With respect to the duration of the transforma- 

 tion, this amounted in Axolotls Nos. I. to IV. 

 altogether to twelve or fourteen days. Of these, 

 four days were taken by the first changes which 

 occurred while the creature was still in the water ; 

 ihe remaining time, to the completion of the meta- 

 morphosis, was passed on land. Dumeril gives 

 the duration of the metamorphosis as sixteen 

 days. 



The following results of the experiments just de- 

 scribed appear to me to be especially noteworthy : 

 The five Axolotl larvae which can alone be taken 

 into consideration, the others having soon perished, 

 all experienced metamorphosis, and without an ex- 

 ception became Amblystomas. Only one of them, 

 No. I., by persistently swimming at the surface, 

 as was observed at the end of six months, showed 

 a decided tendency to undergo metamorphosis 

 and to adopt aerial respiration. With respect to 

 this specimen it may therefore be confidently 

 assumed that it would have taken to the land, and 

 that metamorphosis would have occurred without 

 artificial aid, just as was the case in the thirty 

 specimens which Dumeril altogether observed. 



