METAMORPHOSIS OF THE AXOLOTL. 405 



by various zoologists, as to Avliy the Axolotl does not transform 

 in those localities. The reason he gives is that the inifailing 

 abundance of food and water, and the innumerable hiding-places 

 amongst the reeds under the banks, constitute for these 

 Batrachians a real paradise where tiiey remain, in spite of the fact 

 that there is nothing to prevent them from leaving the water. 

 Dr. Gadow's explanation appears to be in keeping with the results 

 of both Mile, de Chauvin's and Dr. Powers's experiments. 



The conflicting conclusions arrived at made it highly desirable 

 that further experiments should be undertaken. The lack of 

 success obtained by the majority of those who have attempted to 

 force the Axolotl to transform, has led many zoologists to believe 

 that the change is due to some congenital disposition, possessed 

 only by certain individuals, and that Mile, de Chauvin and the 

 few others who have succeeded in obtaining Amblystomes from 

 the larval form were specially fortunate in the choice of their 

 subjects. Therefore, when I commenced my experiments, I was 

 by no means sanguine of attaining any definite results. 



In August of last year I obtained five Axolotls with very fully 

 developed gills and fins, ranging in length from 105 mm. to 

 138 mm., and therefore probably from six to nine months old. 



The enforced breathing of air, by the gradual absorption of 

 the water, and by the gradual elimination of the necessary amount 

 of oxygen from the water, starvation and irregular feeding, and 

 increased temperature having all been given or suggested as 

 means of obtaining the metamorphosis, I placed the animals 

 under the following conditions: — 



Nos. 1 &, 2. — In shallow water so that after the first week 

 only the top of the animal's head and fins remained un- 

 covered, thus forcing the creature to make free use of its 

 lungs. These I kept at a uniform temperature of between 

 75° and 80°. 



IS'os. 3 &, 4. — Under similar conditions, but at a uniform 

 temperature of between 55° and 60°. 



No. 5. — In deep water fi'om which the necessary amount of 

 oxygen was eliminated by the gradual substitution of 

 boiled water and by the introduction of decomposing 

 vegetable matter. 



As at the time I could not obtain any more Axolotls of the size 

 required, I decided to abstain from experimenting with the 

 feeding, until I had either obtained negative results with those I 

 was about to experiment on or had secured more suitable spe- 

 cimens. Nearly a month later I was fortunate enough to obtain 

 six further suitable specimens. At the same time some of the 

 first brood showed signs of metamorphosing in spite of the fact 

 that they had fed with the greatest regularity. I therefore decided 

 not to abstain from offering them food as success seemed likely 

 without resorting to starvation, and placed the individuals of 

 the second brood, which shall be referred to as numbers 6, 7, 8, 9, 



28* 



