[259] As we do not know the origin of the “Paris Axolotl” I must restrict myself in the following remarks to Siredon Mexicanus (Shaw).
[260] Mühlenpfordt, “Versuch einer getreuen Schilderung der Republik Mejico,” Hanover, 1844, vol. ii. p. 252.
[261] [The specific gravity of sea water (Atlantic), according to the determinations of Mr. Buchanan on board the “Challenger,” at 15.56° C. varies from 1.0278 to 1.0240. That of the water of the Dead Sea is 1.17205.—Watts’ “Dict. of Chemistry,” vol. v., table, p. 1017. R.M.]
[262] Loc. cit. p. 252.
[263] “Über die specifische Verschiedenheit des gefleckten und des schwarzen Erdsalamanders oder Molchs, und der höchst merkwürdigen, ganz eigenthümlichen Fortpflanzungsweise des Letzteren.” Isis, Jahrg. 1833, p. 527.
[264] The experiments referred to have not been made known; I am indebted for them to a written communication kindly furnished by an esteemed colleague.
[265] See Mühlenpfordt’s work already quoted, vol. i.
[266] In the province of botany such a case has already been made known by Fritz Müller (Botan. Zeitung, 1869, p. 226; 1870, p. 149). I may be here permitted to quote a passage from the letter in which Dr. Müller calls attention to this interesting discovery. “As a proof of the possibility that a reversion form can again become a persistent character in a species or in the allied form of a particular district, I may refer you to an Epidendrum of the island of Santa Catharina. In all Orchids (with the exception of Cypripedium) only one anther is developed; in very rare cases well-formed anthers appear as reversions among the aborted lateral anthers of the inner whorl. In the Epidendrum mentioned, these are however always present.”
[267] [This species is interesting as being ovoviviparous, the young passing through the branchiate stage within the body of the mother. Some experiments, which were partially successful, were made by Fräulein v. Chauvin with a view to solve the question whether the branchiate stage could be prolonged by taking the larvæ directly from the mother before birth and keeping them in water. See “Zeit. für wissen. Zoo.” vol. xxix., p. 324. R.M.]
[268] See Fatiot, “Les Reptiles et les Batraciens de la haute Engadine.” Geneva, 1873.