as_ found in the
vicinity of the two lakes."

In Gadow's opinion, the reason why there are only perennibranchiate
axolotls in these lakes is obvious. The constant abundance of food, stable
amount of water, innumerable hiding-places in the mud, under the 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 case observed in the Italian
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 Marie von Chauvin. When once sexually ripe the axolotl are apparently
incapable of changing, but their ancestral course of evolution is still
latent in them, and will, if favoured by circumstances, reappear in
following generations.

BIBLIOGRAPHY.--G. Cuvier, _Mem. Instit. Nation._ (1807), p. 149, and in A.
Humboldt and A. Bompland, _Observ. zool._ i. (1811), p. 93; L. Calori,
_Mem. Acc. Bologna_, iii. (1851), p. 269; A. Dumeril, _Comptes rendus_, lx.
(1865), p. 765, and _N. Arch. Mus._ ii. (1866), p. 265; E. Blanchard,
_Comptes rendus_, lxxxii. (1876), p. 716; A. Weismann, _Z. wiss. Zool._
xxv. (Suppl. 1875), p. 297; M. von Chauvin, _Z. wiss. Zool._ xxvii. (1876),
p. 522; F. de Filippi, _Arch. p. la zool._ i. (1862), p. 206; G. Hahn,
_Rev. Quest. Sci._ Brussels (2), i. (1892), p. 178; H. Gadow, _Nature_,
lxvii. (1903), p. 330.

(G. A. B.)

AXUM, or AKSUM, an ancient city in the province of Tigre, Abyssinia (14deg
7' 52" N., 38deg 31' 10" E.; altitude, 7226 ft), 12 m. W. by S. of 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 inscriptions in the place, is found
in classical and early Christian writers in the forms of Auxome, Axumis,
Axume, &c., the first mention being in the _Periplus Maris Erythraei_ (c.
A.D. 67), where it is said to be the seat of a kingdom, and the emporium
for the ivory brought from the west. For the history of this kingdom see
ETHIOPIA. J. T. Bent co