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AXOLOTL
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AXOLOTL , the Mexican name given to larvae salamanders of the genus Amblystoma. It required the extraordinary acumen of the See also:great See also:Cuvier at once to recognize, when the first specimens of the Gyrinus edulis or Axolotl of See also:Mexico were brought to him by See also:Humboldt in the beginning of the 19th See also:century, that these Batrachians were not really related to the Perennibranchiates, such as See also:Siren and See also:Proteus, with which he was well acquainted, but represented the larval See also:form of some See also:air-breathing See also:salamander. Little heed was paid to his See also:opinion by most systematists, and when, more than See also:half a century later, the axolotl was found to breed in its branchiferous See also:condition, the question seemed to be settled once for all against him, and the genus Siredon, as it was called by J. Wagler, was unanimously maintained and placed among the permanent gill-breathers. It seemed impossible to admit that an See also:animal which lives for years without losing its gills, and is able to propagate in that See also:state, could be anything but a perfect form. And yet subsequent discoveries, which followed in rapid See also:succession, have established that Siredon is but the larval form of the salamander Amblystoma, a genus See also:long known from various parts of See also:North See also:America; and Cuvier's conclusions now read much better than they did half a century after they were published. Before reviewing the See also:history of these discoveries, it is desirable to say a few words of the characters of the axolotl (larval form) and of the Amblystoma (perfect or imago form). The axolotl has been known to the Mexicans from the remotest times, as an See also:article of See also:food regularly brought from neighbouring lakes to the Mexico See also:market, its flesh being agreeable and whole-some. Francisco Hernandez (1514-1578) has alluded-Co it as Gyrinus edulis or atolocatl, and as lusus aquarum, piscis ludicrus, or axolotl, which latter name has remained in use, in Mexico and elsewhere, to the See also:present See also:day. But for its large size—it grows to a length of eleven inches—it is a nearly exact See also:image of the See also:British See also:newt larvae. It has the same moderately long, plump See also:body, with a See also:low dorsal See also:crest, the continuation of the membrane bordering the strongly compressed tail; a large thick See also:head with small eyes without lids and with a large pendent upper See also:lip; two pairs of well-See also:developed limbs, with See also:free digits; and above all, as the most characteristic feature, three large appendages on each See also:side of the back of the head, fringed with filaments which; in their fullest development, remind one of See also:black See also:ostrich feathers. These are the See also:external gills, through which the animal breathes the See also:oxygen dissolved in the See also:water. The jaws are provided with small See also:teeth in several rows, and there is an elongate patch of further teeth on each side of the front of the See also:palate (inserted on the vomerine and See also:palatine bones). The See also:colour is blackish, or of a dark See also:olive-See also:grey or brownish grey with See also:round black spots or dots.
The genus Amblystoma was established by J. J. See also:Tschudi in 1838 for various salamanders from North America, which had previously been described as Lacerta or Salamandra, and which, so far as See also:general See also:appearance is concerned, differ little from the See also:European salamanders. The body is smooth and shiny, with See also:vertical grooves on the sides, the tail is but feebly compressed, the See also:eye is moderately large and provided with movable lids, and the upper lip is nearly straight. But the dentition of the palate is very different; the small teeth, which are in' a single See also:row, as in the jaws, form a long transverse, continuous or interrupted See also:series behind the inner See also:nares or choanae. The animal leaves the water after completing its See also:metamorphosis, the last See also:stage of which is marked by the loss of the gills. One of the largest and most widely distributed See also:species of this genus, which includes about twenty, is the Amblystoma tigrinum, an inhabitant of both the See also:east and See also:west of the See also:United States and of a considerable See also:part of the cooler parts of Mexico. It varies much in colour, but it may be described as usually See also: It is generally admitted that the axolotls which were kept alive in See also:Europe and were particularly abundant between 187o and 188o are all the descendants of a stock bred in See also:Paris and distributed chiefly by dealers, originally, we believe, by the See also:late P. See also:Car-See also:bonnier. See also:Close in-breeding without the infusion of new See also:blood is probably the cause of the decrease in ,their See also:numbers at the present day, specimens being more difficult to procure andfetching much higher• prices than they did formerly, at least in See also:England and in See also:France. The See also:original axolotls, from the vicinity of Mexico See also:City, it is believed, arrived at the Jardin d'Acclimatation, Paris, late in 1863. They were See also:thirty-four in number, among which was an See also:albino, and had been sent to that institution, together with a few other animals, by See also:order of See also:Marshal See also:Forey, who was appointed See also:commander-in-See also:chief of the See also:French expeditionary force to Mexico after the defeat of General Lorencez at See also:Puebla (May 5th, 1862), and returned to France at the end of 1863, after having handed over the command to Marshal (then General) See also:Bazaine. Six specimens (five See also:males and one See also:female) were given by the Societe d'Acclimatation to See also:Professor A. Dumeril, the See also:administrator of the reptile collection of the Jardin See also:des Plantes, the living specimens of which were at that See also:time housed in a very miserable structure, situated at a See also:short distance from the comparatively sumptuous See also:building which was erected some years later and opened to the public in 1874. Soon after their arrival at the Jardin d'Acclimatation, some of the axolotls spawned, but the eggs, not having been removed from the See also:aquarium, were devoured by its occupants. At the same time, in the Jardin des Plantes, the single female axolotl also spawned, twice in succession, and a large number of See also:young were successfully reared. This, it then seemed, solved the often-discussed question of the perennibranchiate nature of these Batrachians. But a See also:year later, the second See also:generation having reached sexual maturity, new broods were produced, and out of these some individuals lost their gills and dorsal crest, developed movable eyelids, changed their dentition, and assumed yellow spots,—in fact, took on all the characters of Amblystoma tigrinum. However, these transformed salamanders, of which twenty-nine were obtained from 1865 to 187o, did not breed, although their branchiate brethren continued to do so very freely. It was not until 1876 that the axolotl in its Amblystoma state, offspring of several generations of perennibranchiates, was first observed to spawn, and this again took See also:place in the reptile See also:house of the Jardin des Plantes, as reported by Professor E. See also:Blanchard.
The original six specimens received, in 1864 at the Jardin des Plantes, which had been carefully kept apart from their progeny, remained in the branchiate condition, and bred eleven times from 1865 to 1868, and, after a See also:period of two years' See also:rest, again in 187o. According to the See also:report of Aug. Dumeril, they and their offspring gave See also:birth to 9000 or 1o,000 larvae during that period. So numerous: were the axolotls that the Paris Museum was able to distribute to other institutions, as well as to dealers and private individuals, over a thousand examples, which found their way to all parts of Europe, and numberless specimens have been kept in England from 1866 to the present day. The first specimens exhibited in the See also:London Zoological Gardens, in See also:August 1864, were probably part of the original stock received from Mexico by the Societe d'Acclimatation, but do not appear to have bred.
"See also: Now it has been stated that in the lakes near Mexico City, where it was first discovered, the axolotl never transforms into an Amblystoma. This the present writer is inclined to doubt, considering that he has received examples of the normal Amblystoma ligrinum from various parts of Mexico, and that See also:Alfred Duges has described an Amblystoma from mountains near Mexico City; at the same tithe he feels very suspicious of the various statements to that effect which have appeared in so many See also:works, and rather disposed to make See also:light of the ingenious theories launched by biological speculators who have never set See also:foot in Mexico, especially See also:Weismann's picture of the See also:dismal condition of the See also:salt-incrusted surroundings which were supposed to have hemmed in the axolotl—the brackish Lago de Texcoco, the largest of the lakes near Mexico, being evidently in the philosopher's mind. Thanks to the See also:enthusiasm of H. Gadow during his visit to Mexico in the summer of 1902, we are now better informed on the conditions under which the axolotl lives near Mexico City. First, he ascertained that there are no axolotis at all in the Lago de Texcoco, thus disposing at once of the Weismannian explanation; secondly, he confirmed A. Duges's statement that there is a second species of Amblystoma, which is normal in its See also:meta-morphosis, near Mexico but at a higher See also:altitude, which may explain Velasco's observation that regularly transforming Amblystomas occur near that city; and thirdly, he made a careful examination of the two lakes, Chalco and Xochimilco, where the axolotis occur in abundance and are procured for the market. The following is an abstract of Gadow's very interesting See also:account. " Lakes Chalco and Xochimilco are a See also:paradise, situated about so ft. higher than the Texcoco See also:Lake and separated from it by several hills. High mountains slope down to the See also:southern shores, with a See also:belt of fertile pastures, with shrubs and trams and little streams, here and there with rocks and ravines. In fact, there are thousands of inviting opportunities for newts to leave the. lake if they wanted to do so. Lake Xochimilco contains powerful springs, but away from them the water appears dark and muddy, full of suspended fresh and decomposing See also:vegetable See also:matter, teeming with See also:fish, larvae of See also:insects, Daphniae, See also:worms and axolotl. These breed in the beginning of See also:February. The native fishermen know all about them; how the eggs are fastened to the water See also:plants, how soon after the little larvae swarm about in thousands, how fast they grow, until by the See also:month of See also:June they are all grown into big, See also:fat creatures ready for the market; later in the summer the axolotls are said to take to the rushes, in the autumn they become scarce, but none have ever been known to leave the water or to metamorphose, nor are any perfect Amblystomas found in the vicinity of the two lakes." In Gadow's opinion, the See also:reason why there are only perennibranchiate axolotis in these lakes is obvious. The See also:constant abundance of food, See also:stable amount of water, innumerable hiding-places in the mud, under the See also:banks, amongst the reeds and roots of the floating islands which are scattered all over them,—all these points are inducements or attractions so great that the creatures remain in their paradise and consequently retain all those larval features which are not directly connected with sexual maturity. There is nothing whatever to prevent them from leaving these lakes, but there is also nothing to induce them to do so. The same applies occasionally to European larvae, as in the See also:case observed in the See also:Italian See also:Alps by F. de Filippi. Nevertheless, in the axolotl the latent tendency can still be revived, as we have seen above and as is proved by the experiments of See also:Marie von See also:Chauvin. When once sexually ripe the axolotl are apparently incapable of changing, but their ancestral course of See also:evolution is still latent in them, and will, if favoured by circumstances, reappear in following generations. ri 206; G. See also:Hahn, Rev. Quest. Sci. See also:Brussels (2), i. (1892), p. 178; H. Gadow, Nature, See also:xxvii. (1903), p. 330. (G. A. B.) AXUM, or AKsubt, an See also:ancient city in the See also:province of See also:Tigre, See also:Abyssinia (14° 7' 52" N., 38° 31' 10" E.; altitude, 7226 ft.), 12 M. W. by S. of See also:Adowa. Many European travellers have given descriptions of its monuments, though none of them has stayed there more than a few days. The name, written Aksm and Aksum in the Sabaean and Ethiopic See also:inscriptions in the place,is found in classical and See also:early See also:Christian writers in the forms of Auxome, Axumis, Axume, &c., the first mention being in the Periplus Maria Erythraei (c. A.D. 67), where it is said to he the seat of a See also:kingdom, and the See also:emporium for the See also:ivory brought from the west. For the history of this kingdom see See also:ETHIOPIA. J. T. See also:Bent conjectured that the seat of See also:government was transferred to Axum from Jeha, which he identified with the ancient See also:Ava; and according to a document quoted by Achille Raffray the third Christian monarch transferred it from Axum to Lalibela. This second transference probably took place very much later; in spite of it, the See also:custom of crowning Abyssinian See also:kings at Axum continued, and See also: 7 in. extreme front width; others that are fallen may have been taller. The highly finished monoliths are all representations of a many-storeyed See also:castle, with an See also:altar at the See also:base of each. They appear to be connected with Semitic See also:sun-See also:worship, and are assigned by Bent to the same period as the See also:temple at See also:Baalbek, though some antiquarians would place them much earlier; the See also:representation of a castle in a single See also: Additional information and CommentsThere are no comments yet for this article.
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