14 J. H. Pozvers 



In astonishing contrast to the form assumed by this animal, and: 

 still more accentuating its pecuharities by the effect of contrast 

 was the form assumed by another larva introduced into the same 

 pan a few weeks later. It was one of the few whose appetite was 

 in no wise checked by the change in surroundings ; on the con- 

 trary, the stimulus of the new food (chopped liver) brought 

 about a period of prodigious feeding. A hypertrophied develop- 

 ment of a type which, in greater or less degree, invariably results 

 from such eating followed. The animal developed in all its lat- 

 eral dimensions, save perhaps breadth of mouth ; the head became 

 almost triangular in outline ; the gills, with thick, heavy rami and 

 luxuriant fimbriae, carried out the lines of the head by growing 

 backward, cape-like, two-thirds of the distance to the posterior 

 limbs. The body became daily heavier and more distended, until 

 almost the semblance of salamandrine proportions was lost. The 

 more so in that the back, frequently out of water, became devoid 

 almost of fin and perfectly smooth, and the tail, although still 

 quite larval, remained narrow and extremely short. The limbs 

 were strong and were used upon the slightest provocation. It 

 was this latter fact that accentuated to the last degree the ap- 

 parent unlikeness of these two animals which, at six centimeters 

 in length, had resembled each other as cloesly as if members of 

 one brood. Stimulate the two by jarring the pan, and while the 

 slender larva swept about, even in the shallowest water, with its 

 graceful, limbless, serpentine curves, the other, disdaining en- 

 tirely the use of its body and well-nigh entirely of its tail, struck 

 out with limb movements so vigorous and so rapid, although it 

 could not travel through the shallowest water, that one observer 

 exclaimed : "It looks for the world like a mouse in a wash bowl." 

 This instance, though extreme, is none the less typical of a num- 

 ber which I have closely watched, in which distinct habits of loco- 

 motion have obviously been imposed upon the animal as the result 

 of its nutrition. Once started, these habits of locomotion again 

 react upon the structure. But it seemed of interest to establish 

 the fact that initial differences in appetite alone may finally result 

 in the production of individuals differing from one another quite 



