1911 Encyclopædia Britannica/Salamander
|←Salamanca (New York)||1911 Encyclopædia Britannica, Volume 24
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SALAMANDER. Salamanders in the restricted sense (genus Salamandra of N. Laurenti) are close allies of the newts, but of exclusively terrestrial habits, indicated by the shape of the tail, which is not distinctly compressed. The genus is restricted in its habitat to the western parts of the Palaearctic region and represented by four species only: the spotted salamander, S. maculosa, the well-known black and yellow creature inhabiting Central and Southern Europe, North-West Africa and South-Western Asia; the black salamander, S. atra, restricted to the Alps; S. caucasica from the Caucasus, and S. luschani from Asia Minor. Salamanders, far from being able to withstand the action of fire, as was believed by the ancients, are only found in damp places, and emerge in misty weather only or after thunderstorms, when they may appear in enormous numbers in localities where at other times their presence would not be suspected. They are usually much dreaded by country people, and although they are quite harmless to man, the large glands which are disposed very regularly on their smooth, shiny bodies, secrete a very active, milky poison which protects them from the attacks of many enemies.
The breeding habits of the two well-known European species are highly interesting. They pair on land, the male clasping the female at the arms, and the impregnation is internal. Long after pairing the female gives birth to living young. S. maculosa, which lives in plains or at low altitudes (up to 3000 ft.), deposits her young, ten to fifty in number, in the water, in springs or cool rivulets, and these young at birth are of small size, provided with external gills and four limbs, in every way similar to advanced newt larvae. S. atra, on the other hand, inhabits the Alps between 2000 and 9000 ft. altitude. Localities at such altitudes not being, as a rule, suitable for larval life in the water, the young are retained in the uterus, until the completion of the metamorphosis. Only two young, rarely three or four, are born, and they may measure as much as 50 mm. at birth, the mother measuring only 120. The uterine eggs are large and numerous, as in S. maculosa, but as a rule only one fully develops in each uterus, the embryo being nourished on the yolk of the other eggs, which more or less dissolve to form a large mass of nutrient matter. The embryo passes through three stages — (1) still enclosed within the egg and living on its own yolk; (2) free, within the vitelline mass, which is directly swallowed by the mouth; (3) there is no more vitelline mass, but the embryo is possessed of long external gills, which serve for an exchange of nutritive fluid through the maternal uterus, these gills functioning in the same way as the chorionic villi of the mammalian egg. Embryos in the second stage, if artificially released from the uterus, are able to live in water, in the same way as similarly developed larvae of S. maculosa. But the uterine gills soon wither and are shed, and are replaced by other gills differing in no respect from those of its congener.
Authorities. — Marie von Chauvin, Zeitschr. Wiss. Zool. xxix. (1877), p. 324; P. Kammerer, Arch. f. Entwickel. xvii. (1904), p. 1; Mme. Phisalix-Picot, Recherches embryologiques, histologiques et physiologiques sur les glandes à venin de la salamandre terrestre (Paris, 1900, 8vo).