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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



regions for food. It is a lizard-like animal ; pos- 

 sesses a fin-like flattened tail which forms an effi- 

 cient swimming-organ ; and, as a further adapta- 

 tion to an aquatic existence, possesses three well- 

 developed and fringe-like gills on each side of its 

 neck. Lungs also exist in the axolotl, which is 

 thus a most typical " amphibian," in so far as the 

 possession of a double set of respiratory organs 

 is concerned. Its length is about ten or twelve 

 inches, and its color a dark brown spotted with 

 black. The axolotl has been long known to sci- 

 ence as an interesting amphibian ; but the possi- 

 bility that it was only an immature or larval form 

 of some other amphibian formed perhaps the 

 most noteworthy point in its history. Cuvier 

 appears to have had doubts of its identity ; and 

 Mr. Baird, writing of the axolotl, thus says : " It 

 so much resembles the larva of Amblystoma punc- 

 tata (a North American newt), in both external 

 form and internal structure, that I cannot but be- 

 lieve it to be the larva of some gigantic species 

 of the genus." Nothing very definite, however, 

 could be urged in support of the idea that the 

 axolotl was a creature still in the days of its 

 youth ; and there existed, moreover, one feature 

 which strongly militated against such a supposition 

 — namely, that these animals were capable of per- 

 fectly reproducing their species, since they were 

 known to produce young freely, both in a state 

 of nature and captivity. Of all physiological tests 

 of an animal's maturity this latter may be said to 

 be that of the most general application. The law 

 that the perpetuation of the species is a function of 

 adult life only, is, in fact, one of the most univer- 

 sal application. But, in 1857, Dumeril laid before 

 the French Academy of Sciences a communica- 

 tion in which he noted the instructive fact that 

 some thirty axolotls had mysteriously emigrated 

 from the water in which they lived peacefully 

 with huudreds of their neighbors, had shed their 

 gills, cast off their skin, and had assumed the 

 color and appearance of the genus Amblystoma — 

 a well-known group of American land-newts, 

 which, like other amphibia, possess gills in early 

 life, but breathe when adult by lungs alone. 

 This transformation of the axolotl into a com- 

 pletely different animal, with which it was not 

 known to possess any relationtionship whatever, 

 excited, as might be supposed, no small amount 

 of interest, especially when the presumably adult 

 nature of the axolotls was kept in view. Prof. 

 Marsh, of New Haven, United States, has placed 

 on record the fact that a species of axolotl {Sire- 

 don lichenoides) common in the western parts of 

 the United States also loses its gills and fins when 

 kept in confinement, and also exhibits other 



changes of structural nature. This species fur- 

 ther assumes the likeness of a species of Ambly- 

 stoma (A. mavortium) ; and Prof. Marsh has 

 also remarked that the changes just described 

 occur when these axolotls are brought from their 

 native lakes — situated in the Rocky Mountains at 

 an altitude of 4,500 to 7,000 feet — to the sea-level. 

 The exact cause of these curious changes has 

 only recently, and through the perssverance and 

 ingenuity of a lady experimenter, Friiulein Marie 

 von Chauvin, been brought to light. This lady's 

 experiments confirm in a very striking manner the 

 ideas biologists have been led to form regarding the 

 influence of surrounding conditions, not merely 

 on living beings in the present but in their past 

 history as well. Dumeril, thinking that excision of 

 the gills might induce the change of form, cut off 

 these organs in the axolotls, but without obtaining 

 a successful result ; the animals simply producing 

 new gills in virtue of the power of replacing lost 

 parts so common in their class. But Friiulein 

 von Chauvin, by dint of care and patience, suc- 

 ceeded in enticing five specimens from their na- 

 tive waters by gradually inuring them to a terres- 

 trial existence. The animals were highly refrac- 

 tory as far as their feeding was concerned ; but 

 their objections to diet when under experimenta- 

 tion were overcome by the ingenious method of 

 thrusting a live worm into the mouth ; while by 

 punching the tail of the worm, it was made to 

 wriggle so far down the amphibian's throat that 

 the animal was compelled to swallow the morsel. 

 Of the five subjects on which the patience of Frau- 

 lein von Chauvin was exercised, three died, after 

 a life of nearly fifty days on land. At the period 

 of their death, however, their gills and tail-fins 

 were much reduced as compared with the normal 

 state of these organs. The two surviving axolotls, 

 however, behaved in the most satisfactory manner. 

 Gills and tail-fins grew "small by degrees and 

 beautifully less," and apparently by an actual 

 process of drying and shriveling through con- 

 tact with the outer air, as opposed to any internal 

 or absorptive action. The animals moulted or 

 shed their skin several times ; and finally, as time 

 passed, the gills and tail-fin wholly disappeared, 

 the gill-openings became closed, the flattened tail 

 of the axolotls was replaced by a rounded ap- 

 pendage, the eyes became large, and ultimately, 

 with the development of a beauliful brownish- 

 black hue and gloss on the skin, varied with yel- 

 low spots on the under parts, the axolotls assumed 

 the garb and guise of the land Amblystomas. It 

 was thus clearly proved that a change of sur- 

 roundings — represented by the removal of the 

 axolotls from the water, and by their being grad- 



