[279] [See preceding note 52. R.M.]
[280] See note [226], p. [566].
[281] [Prof. Semper also remarks (“Animal Life,” note 47, p. 430) with reference to the Axolotl of Lake Como in the Rocky Mountains, which he states always becomes transformed into Amblystoma Mavortium, that this metamorphosis “takes place in the water, and the Amblystomas, so long as they are little, actually live exclusively in the water, as I know by my own experience. A young Amblystoma which I kept alive for a long time, never went out of the water of its own free will, while one nearly twice as large lives entirely on land and only takes a bath now and then. It always goes into the water when the temperature of the air in the cellar, in which my aquaria stand, falls below that of the water—down to about 6° or 8° C.” This statement appears to suggest that the effect of temperature may be a factor in some way concerned in these interesting cases of transformation, and would in any case be well worthy of experimental investigation. Some further details concerning the Siredon Lichenoides of Lake Como have been recently published by Mr. W. E. Carlin (Proc. U.S. National Museum, June, 1881). The lake, which is shallow, is fed by a constant stream of fresh water, but the water of the lake is intensely saline. The Siredon never enter the fresh water stream, but congregate in large numbers in the alkaline waters of the lake. “When about one hundred and fifty were placed in fresh water they seemed to suffer no inconvenience, but it had a remarkable effect in hastening their metamorphosis into the Amblystoma form. Of an equal number kept in fresh water and in the lake water, quite a change occurred with the former after twenty-four hours, while the latter showed no change after several days of captivity. Those that were kept well fed in jars usually began to show a slight change in from two to three weeks, and all of them completed the change into the Amblystoma inside of six weeks, while in some kept, but not specially fed, there were but three changes in three months.” (Nature, Aug. 25th, 1881, p. 388.) R.M.]
[282] [Some experiments on the transformation of the Crustacean Artemia Salina into A. Milhausenii by gradually increasing the saltness of the water, and conversely, the transformation of A. Milhausenii into A. Salina by diminishing the saltness of the water, have been made by Schmankewitsch (Zeitschrift f. wiss. Zool. xxv. Suppl. 103 and xxix. 429), but the changes which occur here are much less considerable than in the case of the Axolotl. R.M.]
[283] “Reden und kleinere Aufsätze, Th. II.: Studien aus dem Gebiete der Naturwissenschaften.” St. Petersburg, 1876, p. 81.
[284] This obviously does not imply that the naturalist should not investigate Nature’s processes, and not only correlate these, but also work them up into a universal conception; this is indeed both desirable and necessary if natural knowledge is to be regarded in its true value. The naturalist by this means becomes a philosopher, and the vitality of the so-called “natural philosopher” has been inspired, not by the necessity for investigation, but by philosophy proper.
[285] [The discovery here referred to is the synthesis of urea by Wöhler in 1828 (Pogg. Ann. xii., 253; xv. 619), by the molecular transformation of ammonium cyanate. Since that period large numbers of organic syntheses have been effected by chemists, and many of the compounds formerly supposed to be essential products of life have been built up in the laboratory from their inorganic elements. The division of chemistry into “organic” and “inorganic” is thus purely artificial, and is merely retained as a matter of convenience, the former division of the science being defined as the chemistry of the carbon compounds. R.M.]
[286] “Wahreit und Irrthum im Darwinismus.” Berlin, 1875.
[287] [Eng. ed. I have been reproached by competent authorities for having clothed my ideas upon the theory of selection in the form of a reply to Von Hartmann. I willingly admit that this author cannot be considered as the leader of existing philosophical views upon the theory of descent in Germany; Frederick Albert Lange has certainly a much greater claim to this position. Lange does not however combat this theory; he accepts and develops it most beautifully and lucidly on a sound philosophical basis in such a manner as has never been done before from this point of view (“Geschichte des Materialismus,” 3rd. ed., 1877, vol. ii. pp. 253–277). On most points I can but agree with Lange. Von Hartmann, however, whose objections appeared to me to be supported by a wide scientific knowledge, afforded me a suitable opportunity of developing my own ideas upon some essential points in the theory of selection. In this sense only have I attempted to interfere with this author, the refutation of his views, as such, having been with me a secondary consideration.] [The chief exponent of the doctrine of organic evolution in this country is Mr. Herbert Spencer, in whose “Principles of Biology,” vol. i. chap. xii., will be found a masterly treatment of the theory of descent from a “mechanical” point of view. R.M.]
[288] [The above views on the nature of variability, which were also broadly expressed in the first essay “On the Seasonal Dimorphism of Butterflies” (pp. [114], 115), are fully confirmed by Herbert Spencer (loc. cit. chaps. ix. and x.), and more recently by A. R. Wallace in an article on “The Origin of Species and Genera” (Nineteenth Century, vol. vii., 1880, p. 93). See also some remarks by Oscar Schmidt in his “Doctrine of Descent and Darwinism,” Internat. Scien. Ser. 3rd. ed. 1876, p. 173. R.M.]