4°4 



THE AM ERIC AX NATURALIST. [Vol. XXXVII. 



under water? Marie von Oiauvin found that the larvae of 

 full conclusion. 



The attempts to produce the perfect adult Amblystoma under 

 water were not successful, although they fell little short of suc- 

 cess. Advanced stages of metamorphosis were produced; in 

 one instance only a trace of tail-fin and gill-stubs remaining. 

 As already indicated, the great difficulty encountered was the 

 unexpected fact that all of the larva' are air breathers, no mat- 

 ter how complete the development of the branchiae. No larva 

 could be found capable of living for more than twenty-four hours 

 below the surface of standing water, no matter how pure, or how 

 large the volume. Their tenacity of life varied much. In a few 

 instances, by repeatedly reviving the semi asphyxiated animal in 

 air, or in running water, and replacing it in well aerated water, 

 under the netting, a partial adaptation seemed to be brought 

 about. Fewer movements were made and no distress or impulse 

 toward the surface would be shown for many hours. But grad- 

 ual or acute suffocation always occurred sooner or latter. When 

 a small stream of water was let fall directly into the aquarium — 

 in this case usually only a battery jar — the results were better ; 

 although many did not live long, when situated even thus, and 

 when the stream was checked, even for an hour, our very best 

 water-breathers always made efforts to reach the surface. 



Although complete metamorphosis was not reached under 

 water, yet the theoretical importance of the partial metamor- 



to the completion of the process 7 The impulse to metamorphose 



that could there resist the tendency to starvation-metamorphosis. 

 All, which did not die of some other cause, began metamorphosis, 



was begun almost immediately, as if the first shock of transfer- 

 ence and partial oxygen-starvation were enough, despite the low 

 temperature, to induce the change. Such individuals, did not, 

 however, survive long; those which carried metamorphosis to 



