ANIMALS AND THEIR ENVIRONMENTS. 



239 



ually inured to a terrestrial existence — has the 

 effect of metamorphosing them into not merely a 

 new species, but apparently an entirely different 

 genus of animals. 



The bearings of this case will be more fully 

 noted hereafter ; but we may, as a last example 

 of the influence of surroundings on animal exist- 

 ence, mention Fraulein vonChauvin's experiments 

 on the Black Alpine Salamander (Salamanda 

 atra), a species of land-newt, living on the Alpine 

 range, at heights of about 1,000 feet above the 

 sea-level, and in comparatively dry places. As in 

 all other amphibians, the young possess gills, but 

 the possession of gills by immature creatures in 

 dry and stony places would appear to place the 

 animals at a singular disadvantage. How, them 

 has Nature surmounted the difficulty, and adapted 

 the young animals to their surroundings ? Sim- 

 ply by causing the young to undergo their meta- 

 morphosis within the body of the parent — these 

 animals being ovo-viviparous, that is, retaining the 

 eggs within their bodies until the young are 

 hatched. Thus the young of the Alpine salamander 

 pass their "gilled" condition within the parental 

 body, instead of in water, as do the young of our 

 common newts. But, it might be asked, did the 

 young of the Alpine salamander at any previous 

 period in the history of the species ever live in 

 water — in other words, is their present an acquired 

 condition or not ? Fraulein von Chauvin's exper- 

 iments supply a clear reply to this question. Of 

 two young salamanders possessing external gills 

 which were taken from the body of the parent and 

 which were placed in water, one died ; the surviv- 

 or casting off its first set of gills four days after- 

 ward, and actually developing a second and larger 

 set of unusual form, but probably resembling those 

 with which these animals in their original water, 

 habitation were provided. A tail-fin was also devel- 

 oped, and for fifteen weeks this young salamander, 

 at a time when it should have been living a terres- 

 trial existence, enjoyed its life in water. At the 

 expiry of that period, however, the gills were 

 cast off, and the animal appeared in the likeness 

 of its land-living parent. Succeeding experiments 

 of Fraulein von Chauvin on the development of 

 the Alpine salamander served to reveal other in- 

 teresting details, supplementing in a remarkable 

 manner that lady's previous observations. Five 

 larva?, the survivors of a set of twenty-three, were 

 placed in water ; one of these young salamanders 

 being somewhat more advanced in development 

 than the others. The youngest of the four pos. 

 sessed six red gills of branched form, and of such 

 a size that they appeared to impede its move- 

 ments in swimming. Soon after being placed in 



the water, these gills began to shrivel, and were 

 finally rubbed off by the movements of the ani- 

 mal against the sides of the aquarium : so that it 

 appeared to be entirely destitute of breathing-or- 

 gans. It lay quiescent in the bottom of the vessel 

 for three days, three new gills of different struct- 

 ure from the first organs being then developed 

 on each side of the head, while the new breath- 

 ing-organs were much shorter than the discarded 

 gills. A new tail-fin had also been developed in 

 place of the first with which it was provided, the 

 second appendage being the larger of the two. 

 After fourteen weeks of aquatic life, the gills be- 

 gan to decrease in size, and the tail to become 

 rounded, and in a few days more the young animal 

 quitted the water and assumed the form, color, 

 and entire aspect of the adult. The second spe- 

 cimen, which, as already remarked, was more ad- 

 vanced in development than the first, assumed 

 the likeness of the adult after a much shorter ex- 

 istence in the water. The young appeared to be 

 perfectly at home in the water, and fed greedily 

 when they entered it ; this fact being somewhat 

 remarkable in view of the present life and modern 

 development of the species. 



That the present course of development in the 

 Alpine salamander is an acquired condition, and 

 one altered from its original state, there can be no 

 doubt. Its mere relationship to its amphibian 

 kith and kin proves this assertion to be true ; 

 while the fact that the young will live for an ex- 

 tended period in water, and the mere presence of 

 gills in the young state, place the altered nature 

 of these animals beyond a doubt. The develop- 

 ment of useless gills in the young salamander can- 

 not be explained by any such phrases as " adhe- 

 rence to type," "unity of type," "natural sym- 

 metry," and the like — unless, indeed, we may sup- 

 pose that Nature imitates humanity in its anxi- 

 ety for symmetry ,and supplies the young salaman- 

 der with gills which never were used, and which 

 never were meant to be used, on the principle 

 of an architect who places blank windows and 

 painted imitation blinds on a house under the idea 

 of securing uniformity. Such a practice, admit- 

 tedly far from aesthetic in architecture, is positive- 

 ly degrading when applied to the explanation 

 of Nature's ways and works. It is an idea, be- 

 sides, which is founded on pure and baseless 

 assumption, and as such demands no further 

 notice. The opposing view, which regards the 

 gills of the young Alpine salamander as the rep- 

 resentatives of organs which, at a former period in 

 the history of the species, were used for breathing 

 in its water-living stages of development, is, on 

 the other hand, not only reasonable and con- 



