564 Studies in the Theory of Descent. 



Respecting Nos. II., III., and IV., on the other 

 hand, such a supposition is but little probable. 

 These three larvae endeavoured to keep in deep 

 water and avoided as long as possible the shallow 

 places which would have enforced them to take 

 entirely to lung breathing. Metamorphosis thus 

 occurred more than a month later in these 

 individuals. 



Finally, there can scarcely be any doubt that 

 No. V. would not have become transformed without 

 forcible adaptation to an aerial life. 



From these results we may venture to conclude 

 that most Axolotl larvae change into the Ambly- 

 stoma form when, at the age of six to nine months, 

 they are placed in such shallow water that they are 

 compelled to respire chiefly by their lungs. The 

 experiments before us are certainly at present but 

 very few in number, but such a conclusion cannot 

 be termed premature if we consider that out of 

 several hundred Axolotls (the exact number is not 

 given) Dumeril obtained only about thirty Ambly- 

 stomas, while v. Kolliker bred only one Amblystoma 

 out of a hundred Axolotls. 



It now only remains questionable whether each 

 larva could have been forced to undergo meta- 

 morphosis, but this could only be decided by new 

 experiments. It was originally my intention to 

 have delayed the publication of the experiments 

 till Fraulein v. Chauvin had repeated them in larger 

 numbers, but as my Axolotls have not bred this 



