I HE AM E RICA X XA TURALIST. [Vol. XXXVII. 



left in water which but partially covers them, become at once 

 inactive. After a few efforts to crawl, and ineffectual turnings 

 about, as if in search of water again, they " settle down, and 

 wait for rain." This inactivity partially compensates the first 

 effects of starvation; so that these air breathing larvae may 

 metamorphose even less quickly than similar individuals sub- 

 jected to starvation, but kept in water which encourages move- 

 Second : What of the numerous observations on the meta- 

 morphosis of Amblystoma in the air, as the result of the drying 

 up of ponds ? Do not these, after all, show that metamorphosis 

 frequently follows the enforced use of lungs ? They do, indeed, 

 show that metamorphosis follows the enforced use of lungs ; but 

 not that it is caused thereby. A moment's thought will show 

 that this naive, natural interpretation may well be at fault. As 

 the water of a pond evaporates, what is the first result for these 

 larvae? Plainly a concentration of their food supply. Insect 

 larvae and entomostraca, moderately abundant before, become 

 now indefinitely easy of access. The larvae gorge themselves, for 



accelerating evaporation place them at a disadvantage; freedom 

 of movement is checked, or they find themselves partially out of 

 the water. Experiment shows that under such circumstances 



than those which the writer has found effective under experimental 



It may seem more presumptuous to offer a similar explanation 

 for the results obtained by European exp 

 stoma and interpreted by them in so different a i 

 careful reading of a large part of the literature 



