26o REPTILES AND BATRACHIANS 



of water. Yet most interesting is it to note that even the 

 varying factors of nutrition seem to have been wholly 

 neglected in the final interpretation of the results." 



Dr. Powers's field-notes show that metamorphosis occurs 

 rarely, if ever, as the result of enforced air-breathing 

 through the drying-up of ponds, and that, in spite of 

 repeated search at appropriate times and places, no 

 Axolotls have been found transforming on the mud of 

 drying ponds. 



Dr. Gadow, who not long ago visited the lakes near 

 Mexico City in which this creature lives, and where it is 

 said to retain its branchiate condition, has been able to 

 refute the theories framed by various zoologists, as to why 

 the Axolotl does not transform in those localities. The 

 reason he gives is that the unfailing abundance of food and 

 water, and the innumerable hiding-places amongst the 

 reeds under the banks, constitute for these batrachians 

 a real paradise, where they remain, in spite of the fact that 

 there is nothing to prevent them from leaving the water. 



The writer has himself experimented on the meta- 

 morphosis of the Mexican Axolotl, and succeeded in 

 obtaining the transformation of numerous specimens. 

 His results showed that, in the first place, in accordance 

 with Mile, de Chauvin's observations, and contrary to 

 those of Dr. Powers, the Axolotl will, with a few exceptions, 

 transform into the Amblystome stage if placed, when about 

 five inches in length, under conditions which force it to 

 make free use of its lungs : in the second place, that 

 starvation, irregular feeding, and temperature, all of which 

 have been stated or suggested to cause the creature 

 to transform, has no influence on the metamorphosis : 



