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that most Axolotl larvas, if not all, complete their metamor- 

 phosis, if in the first place they come out of the egg healthy 

 and are properly fed, and in the second place, meet with 

 arrangements which force them to change from breathing 

 under water to breathing above water." 



Dr. J. H. Powers at Doane College, Nebraska, has more 

 recently conducted numerous experiments on the meta- 

 morphosis of North American examples of the Axolotl, and 

 he has come to the conclusion that the metamorphosis is 

 not due, as was thought by Mile, de Chauvin, to a direct 

 response to changes in conditions of environment, compel- 

 ling them to resort to aerial respiration, but to checked 

 nutrition, and that a careful study of Mile, de Chauvin's 

 methods and results seems to cast a doubt upon the con- 

 clusion that enforced air-breathing caused the metamor- 

 phosis. The following is a passage from Dr. Powers's 

 paper on the subject of this lady's experiments : " Fearing 

 that her charges would die, as indeed they sometimes did, 

 she always prepared them for the trying ordeal of meta- 

 morphosis by raising the temperature of the water in which 

 they were kept, and feeding to the maximum for several 

 days, to which she ascribes no other importance than 

 giving the animals increased strength. The Axolotls w^re 

 then brought immediately into water sufficiently shallow 

 as to force them, at least part of the time, to breathe air. 

 In this latter condition the experimenter complains again 

 and again that it was next to impossible to induce the 

 Axolotls to take any food whatever. Thus, in these experi- 

 ments, we have high feeding followed by practical starva- 

 tion, and it seems that no control experiments were insti- 

 tuted to determine what the effects of over and under 

 nutrition might have been with Axolotls still in abundance 



