171 [The slight variability in the colour of this pupa, opens up the interesting question of the photographic sensitiveness of this and other species, which is stated to cause them to assimilate in colour to the surface on which the larva undergoes its final ecdysis. Some experiments upon this subject have been recorded by Mr. T.W. Wood, Proc. Ent. Soc. 1867, p. xcix, but the field is still almost unexplored. R.M.]

172 “Über den Einfluss der Isolirung auf die Artbildung.” Leipzig, 1872, p. 20.

173 In some instances Deilephila Lineata has also been seen by day hovering over flowers.

174 It is true that I only reared one brood, but from this fifty specimens were obtained. It would be interesting to know whether this variety of the caterpillar is distributed over the whole of Southern Europe.

175 In this sense Lubbock says:—“It is evident that creatures which, like the majority of insects, live during the successive periods of their existence in very different circumstances, may undergo considerable changes in their larval organization in consequence of forces acting on them while in that condition; not, indeed, without affecting, but certainly without affecting to any corresponding extent, their ultimate form.”—“Origin and Metamorphoses of Insects,” London, 1874, p. 39.

176 “GrundzÜge der Zoologie,” 1875.

177 [Lepidopterists are of course aware that even these distinctions are not absolute, as no single character can be named which does not also appear in certain moths. The definition in this case, as in that of most other groups of animals and plants, is only a general one. See, for instance, Westwood’s “Introduction to the Classification of Insects,” vol. ii. pp. 330–332. Also some remarks by C.V. Riley in his “Eighth Annual Report” on the insects of Missouri, 1876, p. 170. With reference to the antennÆ as a distinguishing character, see Mr. A.G. Butler’s article in “Science for All,” 1880, part xxvii. p. 65. R.M.]

178 The genus of MorphinÆ, Discophora, possesses hairs very similar to those of the genus Cnethocampa belonging to the BombycidÆ.

179 [The larvÆ of genera 14, Phyciodes, and 35, Crenis, are likewise spiny. See Edwards’ “Butt. of N. Amer.” vol. ii. for figures of the caterpillar of Phyc. Tharos: for notes on the larvÆ of Crenis Natalensis and C. Boisduvali see a paper by W.D. Gooch, “Entomologist,” vol. xiv. p. 36. The larvÆ of genus 55, Ageronia, are also spiny. (See Burmeister’s figure of A. Arethusa, “LÉp. RÉp. Arg.” Pl. V. Fig. 4). The larvÆ of genus 98, Aganisthos, also appear to be somewhat spiny (see Burmeister’s figure of A. Orion, loc. cit. Pl. V. Fig. 6), and this raises the question as to whether the genus is correctly located in its present position. The larvÆ of the following genera figured in Moore’s “Lepidoptera of Ceylon,” parts i. and ii., are all spiny:—6, Cirrochroa (Pl. XXXII.); 7, Cynthia (Pl. XXVI.); 27, Kallima (Pl. XIX.); and 74, Parthenos (Pl. XXIV.). Many species of caterpillars which are spiny when adult appear to be spineless, or only slightly hairy when young. See Edwards’ figures of MelitÆa Phaeton, Argynnis Diana, and Phyc. Tharos (loc. cit.) and his description of the larva of Arg. Cybele, “Canad. Entom.” vol. xii. p. 141. The spiny covering thus appears to be a character acquired at a comparatively recent period in the phyletic development. R.M.]

180 [The larvÆ of the 110th genus, Paphia, Fabr. (AnÆa, HÜbn.) are also smoothed-skinned. See Edwards’ figure (loc. cit. vol. i. Pl. XLVI.) of P. Glycerium. Also C.V. Riley’s “Second Annual Report” on the insects of Missouri, 1870, p. 125. Burmeister figures the larva of a species of Prepona (genus 99) which is smooth (P. Demophon, loc. cit. Pl. V. Fig. 1). The horns on the head of Apatura, &c., may possibly be a survival from a former spiny condition. R.M.]

181 “Synopsis of the described Lepidoptera of North America.” Washington, 1862.

182 “Catalog der Lepidopteren des EuropÄischen Faunengebietes.” Dresden, 1871.

183 This group of moths (“SchwÄrmer”) is regarded as of very different extents by systematists; when I here comprise under it only the SphingidÆ proper and the SesiidÆ, I by no means ignore the grounds which favour a greater extension of the group; the latter is not rigidly limited. [The affinities of the SesiidÆ (ÆgeriidÆ) are by no means clearly made out: it appears probable that they are not related to the SphingidÆ. See note 160, p. 370. R.M.]

184 [For Mr. A.G. Butler’s observations on the genus Acronycta, see “Trans. Ent. Soc.” 1879, p. 313; and note 68, p. 169, of the present volume. R.M.]

185 [The following characters are given in Stainton’s “Manual of British Butterflies and Moths,” vol. i. p. 114:—“Larva of very variable form: at one extreme we find the singular Cerura larvÆ, with only fourteen legs, and two long projecting tails from the last segment; at the other extreme we have larvÆ with sixteen legs and no peculiarity of form, such as Chaonia and Bucephala; most have, however, the peculiarity of holding the hind segment of the body erect when in repose; generally quite naked, though downy in Bucephala and rather hairy in Curtulu; very frequently there are projections on the back of the twelfth segment.” R.M.]

186 Encyl. Meth. ix. p. 310.

187 [The genus Vanessa (in the wide sense) appears to be in a remarkable condition of what may be called phyletic preservation. Thus, the group of species allied to V. C.-album passes by almost insensible steps into the group of butterflies typified by our “Tortoiseshells.” The following is a list of some of the intermediate species in their transitional order:—I.-album, V.-album, Faunus, Comma, California, Dryas, Polychloros, Xanthomelas, Cashmirensis, UrticÆ, Milberti, &c. Similarly, our Atalanta and Cardui are connected by a number of intermediate forms, showing a complete transition from the one to the other. The following is the order of the species so far as I am acquainted with them:—Atalanta, Dejeanii, CallirhoË, Tammeamea, Myrinna, Huntera, Terpsichore, Carye, Kershawii, and Cardui. R.M.]

188 “Prodromus Systematis Lepidopterorum.” Regensburg, 1864.

189 [The larva of Acherontia Morta, figured by Butler (see note 121, p. 262), possesses the characteristically recurved horn; that of Ach. Medusa figured by the same author, does not appear to possess this character in any marked degree. R.M.]

190 [See note 97, p. 233. R.M.]

191 Loc. cit. Pl. XXV. [This species is referred by Butler to the genus Paonias, HÜbn. R.M.]

192 Abbot and Smith, Pl. XXIX. [Placed by Butler in the genus Cressonia, Grote and Robinson. Abbot and Smith state that this larva is sometimes green. According to Mr. Herman Strecker (Lepidop. Rhopal. and Hetero, Reading, Pa. 1874, p. 54) it feeds upon black walnut (Juglans Nigra), hickory (Carya Alba), and ironwood (Ostrya Virginica). Of the North American species of Smerinthus, the following, in addition to ExcÆcatus, closely resemble our Ocellatus:—S. (Calasymbolus) Geminatus, Say; (C.) Cerisii, Kirby; and Ophthalmicus, Boisd. In addition to S. (Cressonia) Juglandis, S. (Triptogon) Modesta much resembles our Populi. The larva of Geminatus, according to Strecker, is “pale green, lightest above, with yellow lateral granulated stripes; caudal horn violet; stigmata red. It feeds on the willow.” R.M.]

193 Cat. Brit. Mus.

194 [This lengthening of the true legs is mimetic according to Hermann MÜller, and causes the anterior portion of the caterpillar to resemble a spider. See note 129, p. 290. R.M.]

195 [Certain butterflies appear to be crepuscular, if not nocturnal in their habits. Thus in his “Notes on the Lepidoptera of Natal,” Mr. W.D. Gooch states that he never saw Melanitis, Leda, or Gnophodes Parmeno on the wing by day, but generally during the hour after sunset. He adds:—“My sugar always attracted them freely, even up to 10 or 11 p.m.” Many species of HesperidÆ are also stated to be of crepuscular habits by this same observer. See “Entomologist,” vol xvi. pp. 38 and 40. R.M.]

196 I only make this assumption for the sake of simplicity, and not because I am convinced that the existing Rhopalocera are actually the oldest Lepidopterous group.

197 Zeitschrift fÜr wissenschaftl. Zoologie, vol. xx. p. 519.

198 [See for instance Lubbock’s “Origin and Metamorphoses of Insects,” chap. iii.; and F.M. Balfour’s “Comparative Embryology,” vol. i., 1880, pp. 327—356. This last work contains an admirable rÉsumÉ of our knowledge of the embryonic development of insects up to the date of publication. R.M.]

199 Are not the 4th, 11th, and 12th segments destitute of the rudiments of legs as in the larvÆ of all existing saw-flies? I might almost infer this from BÜtschli’s figures (see for instance Pl. XXV., Fig. 17A).

200 [The grub-formed Hymenopterous larvÆ, like the larvÆ of all other holometabolous insects, thus represent an acquired degenerative stage in the development, i.e. an adaptation to the conditions of life at that stage. Bearing in mind the above-quoted observations of BÜtschli and the caterpillar-like form of the Terebrantiate group of Hymenopterous larvÆ, the following remarks of Balfour’s (loc. cit. p. 353), appear highly suggestive:—“While in a general way it is clear that the larval forms of insects cannot be expected to throw much light on the nature of insect ancestors, it does nevertheless appear to me probable that such forms as the caterpillars of the Lepidoptera are not without a meaning in this respect. It is easy to conceive that even a secondary larval form may have been produced by the prolongation of one of the embryonic stages; and the general similarity of a caterpillar to Peripatus, and the retention by it of post-thoracic appendages, are facts which appear to favour this view of the origin of the caterpillar form.” See also Sir John Lubbock, loc. cit., pp. 93 and 95. R.M.]

201 [In the most recent works dealing with this order six groups, based on the character of the imagines are recognized, viz.:—Tubulifera, Terebrantia, Pupivora, Heterogyna Fossores, and Mellifera. (See, for instance, F.P. Pascoe’s “Zoological Classification,” 2nd ed. p. 147.) Of these groups the larvÆ of the Terebrantia as thus restricted are all of the caterpillar type (TenthredinidÆ and SiricidÆ), whilst those of the other groups are maggot-shaped. For a description of the development of the remarkable aberrant larva of Platygaster, see Ganin in Zeit. f. wissenschaftl. Zool., vol. xix. 1869. R.M.]

202 [For recent investigations on the structure of the thorax in Diptera, see a paper by Mr. A. Hammond, in Journ. Linn. Soc., Zoology, vol xv. p. 9. R.M.]

203 I am familiar with the fact that the two sub-orders of true Diptera, the short-horned (Brachycera), and the long-horned (Nemocera), are not sharply limited; and I am likewise well acquainted with the circumstance that there are forms which connect the two larval types. The connecting forms of the imagines do not, however, always coincide with the intermediate larval forms, so that there here arises a second and very striking incongruence of morphological relationship which depends only upon the circumstance that the one stage has diverged in form more widely than the other through a greater divergence in the conditions of life. The difficulty is in these cases aggravated because an apparent is added to the true form-relationship through convergence, so that without going into exact details the form and genealogical relationships of the Diptera cannot be distinguished. It would be of great interest for other reasons to make this investigation, and I hope to be able to find leisure for this purpose at some future period.

204 “Entwicklung der Dipteren.” Leipzig, 1864.

205 Lubbock concludes from the presence of thoracic legs in the embryonic larva of bees that these have been derived from a larva of the Campodea type, but he overlooks the fact that the rudiments of the abdominal legs are also present; loc. cit., p. 28.

206 “FÜr Darwin,” Leipzig, 1864, p. 8.

207 Mem. Peabody Acad. of Science, vol. i. No. 3.

208 Verhandl. Wien. Zoolog. Botan. Gesellsch. 1869, p. 310.

209 Über Ontogenie und Phylogenie der Insekten. Eine akademische Preisschrift. Jen. Zeitschrift. Bd. x. Neue Folge, iii. Heft 2. 1876. [Some remarks by F.M. Balfour on the origin of certain larval forms have already been quoted in a previous note (p. 485). This author further states:—“The fact that in a majority of instances it is possible to trace an intimate connection between the surroundings of a larva and its organization proves in the clearest way that the characters of the majority of existing larval forms of insects have owed their origin to secondary adaptations. A few instances will illustrate this point:—In the simplest types of metamorphosis, e.g. those of the Orthoptera genuina, the larva has precisely the same habits as the adult. We find that a caterpillar form is assumed by phytophagous larvÆ amongst the Lepidoptera, Hymenoptera, and Coleoptera. Where the larva has not to go in search of its nutriment the grub-like apodous form is assumed. The existence of such an apodous larva is especially striking in the Hymenoptera, in that rudiments of thoracic and abdominal appendages are present in the embryo and disappear again in the larva.... It follows from the above that the development of such forms as the Orthoptera genuina is more primitive than that of the holometabolous forms, &c.” Comparative Embryology, vol. 1, p. 352. R.M.]

210 [The Aphaniptera are now recognized in this country as a sub-order of Diptera. See, for instance, Huxley’s “Anatomy of Invertebrated Animals,” p. 425, and Pascoe’s “Zoological Classification,” 2nd ed. p. 122. R.M.]

211 [This illustration of course only applies to the old arrangement of the Hymenoptera into Terebrantia and Aculeata. See also note 201, p. 488. R.M.]

212 [Eng. ed. This law is perhaps a little too restricted, inasmuch as it is theoretically conceivable that the organism may be able to adapt itself to similar conditions of life in different ways; differences of form could thus depend sometimes upon differences of adaptation and not upon differences in the conditions of life, or, as I have formerly expressed it, it is not necessary to allow always only one best mode of adaptation.]

213 [It must be understood that the word rendered here and elsewhere throughout this work as “transformation” is not to be taken in the narrow sense of metamorphosis, but as having the much broader meaning of a change of any kind incurred by an organism. Metamorphosis is in fact but one phase of transformation. R.M.]

214 By the Editor.

215 Mr. C.V. Riley in his excellent “Annual Reports” already quoted in previous notes, states that the larvÆ of Agrotis Inermis, Leucania Unipuncta (Army-worm), and L. Albilinea are all loopers when newly hatched. (See First Report, p. 73; Eighth Report, p. 184; and Ninth Report, p. 53.)

216 The following species not referred to in the previous part of this work are figured by Semper (Beit. zur Entwicklungsgeschichte einiger ostasiat. Schmet.; Verhandl. d. k.k. zoo. bot. Gesell. in Wien, 1867):—Panacra Scapularis, Walk.; ChÆrocampa Clotho, Drury; and Diludia (Macrosila) Discistriga, Walk. The following are figured by Boisduval and GuenÉe. (SpÉc. GÉn. 1874):—Smerinthus Ophthalmicus, Boisd.; Sphinx Jasminearum, Boisd.; S. (Hyloicus) Plebeia, Fabr.; S. (Hyloicus) Cupressi, Boisd.; S. (Pseudosphinx) CatalpÆ, Boisd.; Philampelus JussiuÆ, HÜbn. (= Sphinx Vitis, Linn.?); and Ceratomia Amyntor, HÜbn. As the works of Abbot and Smith, and Horsfield and Moore have been exhausted by Dr. Weismann, it is quite unnecessary to extend this note by giving a list of the species figured by these authors.

217 The same inference has already been drawn with respect to Pterogon (Proserpinus) ŒnotherÆ, see pp. 257, 258.

218 This would of course be the fourth segment if the head be considered the first, as on the Continent.

219 “Second Annual Report,” 1870, p. 78.

220 “Entomologist,” vol. xiv. p. 7.

221 With reference to the habits of C. Capensis (p. 531), I have since been informed by Mr. Trimen that this species does not conceal itself by day, so that the dimorphism may be regarded as a character retained from an earlier period and adapted to the present life conditions.

222 “Kosmos,” Dec. 1877, p. 218. The paper is here introduced chiefly with a view to illustrate an important case of incongruence among Lepidopterous pupÆ.

223 [MaracujÁ, the local name for the Passiflora. R.M.]

224 See p. 448.

225 Verhandl. Schweiz. Naturforsch. Gesellschaft. Einsiedeln, 1868.

226 [Eng. ed. In 1878 SeÑor JosÉ M. Velasco published a paper entitled “Description, metamorfosis. y costumbres de una especie nueva del genero Siredon.” Memor. Sociedad Mexicana de Historia Natural, December 26th. See Addendum to this essay.]

227 Dana and Silliman’s Amer. Journ., 3rd series, i. p. 89. Annals Nat. Hist. vii. p. 246.

228 Proc. Zoo. Soc. 1870, p. 160.

229 Compt. Rend., vol. lx. p. 765 (1865).

230 Nouvelles Archives du MusÉum d’Histoire Nat. Paris, 1866, vol. ii. p. 268.

231 Proc. Boston Soc., vol. xii. p. 97; Silliman’s Amer. Journ., vol. xlvi. p. 364; reference given in “Troschel’s Jahresbericht” for 1868, p. 37.

232 Proc. Boston Soc., vol. xii. p. 97; Silliman’s Amer. Journ., vol. xlvi. p. 364. I have not been able to get a copy of this paper, and quote from a reference in “Troschel’s Jahresbericht.” See preceding note.

233 Dana and Silliman’s Amer. Journ. See note 3.

234 Proc. Acad. Philadelph. xix. 1867, pp. 166–209.

235 MÉm. Acad. Petersb. vol. xvi.

236 [Eng. ed. Seidlitz is an exception, since in his work on Parthenogenesis (Leipzig, 1872, p. 13) he states that “In the Axolotl, PÆdogenesis, which is not in this case... monogamous, but sexual, and indeed gynÆkogenetic, has already become so far constant that it has perhaps entirely superseded the orthogenetic reproduction.”]

237 Über den Einfluss der Isolirung auf die Artbildung. Leipzig, 1872, p. 33.

238 DumÉril represents the teeth of the vomer as separated from those of the os palatinum by a gap. This is probably accidental, since Gegenbaur (Friedrich u. Gegenbaur, the skull of Axolotl, WÜrzburg, 1849) figures the rows of teeth as passing over from the one bone to the other without interruption. This was the case with the Axolotls which I have been able to examine on this point; but this small discrepancy is, however, quite immaterial to the question here under consideration.

239 See O. Hertwig “Über das Zahnsystem der Amphibien und seine Bedeutung fÜr die Genese des Skelets der MundhÖhle.” Archiv. fÜr microsc. Anat., vol. xi. Supplement, 1874.

240 [Eng. ed. These Amblystomas have since died and have been minutely described by Dr. Wiedersheim. See his memoir, “Zur Anatomie des Amblystoma Weismanni,” in Zeit. fÜr wiss. Zool., vol. xxxii. p. 216.]

241 See Strauch, loc. cit. p. 10.

242 See Part I. of this volume.

243 [This is the principle of “Degeneration” recognized by Darwin (see “Origin of Species,” 6th ed. p. 389, and “Descent of Man,” vol. i. p. 206), and given fuller expression to by Dr. Anton Dohrn (see his work entitled “Der Ursprung der Wirbelthiere und das Princip des Functionswechsels.” Leipzig, 1875). A large number of cases have been brought together by Prof. E.R. Lankester, in his recent interesting work on “Degeneration, a Chapter in Darwinism.” Nature series, 1880. R.M.]

244 “Sulla Larva del Triton Alpestris.” Archivio per la Zoologia. Genova e Torino, 1861, vol. i. pp. 206–211.

245 See also Lubbock “On the Origin and Metamorphoses of Insects,” London, 1874.

246 See the first essay “On the Seasonal Dimorphism of Butterflies,” p. 82.

247 [Eng. ed. It has frequently been objected to me that the existing Axolotl is not a form resulting from atavism, but a case of “arrested growth.” The expression “atavism” is certainly to be here taken in a somewhat different sense than, for example, in the case of the reversion of the existing Axolotl to the Amblystoma form. Further on, I have myself insisted that in the first case the phyletic stage in which the reversion occurred is still completely preserved in the ontogeny of each individual, whilst the Amblystoma stage has become lost in the ontogeny of the Axolotl. If, therefore, we apply the term “atavism” only to such characters or stages (i.e. complexes of characters) as are no longer preserved in the ontogeny, we cannot thus designate the present arrest of the Axolotl at the perennibranchiate stage. Such a restriction of the word, however, appears to me but little desirable, since the process is identical in both cases, i.e. it depends upon the same law of heredity, in accordance with which a condition formerly occurring as a phyletic stage suddenly reappears through purely internal processes. It is true that the reversion is not complete, i.e. the present sexually mature Axolotl does not correspond in all details with its perennibranchiate ancestors. Since Wiedersheim has shown that the existing Axolotl possesses an intermaxillary gland, this can be safely asserted. This gland occurs only in land Amphibians, and therefore originated with the Amblystoma form, afterwards becoming transferred secondarily to the larval stage. Nevertheless, the present Axolotl must resemble its perennibranchiate ancestors in most other characters, and we should be the more entitled to speak of a reversion to the perennibranchiate stage as we speak also of the reversion of single characters. To this must be added that the Axolotl does not correspond exactly with an Amblystoma larva, since Wiedersheim has shown that the space for the intermaxillary gland is present, but that the gland itself is confined to a few tubes which do not by any means fill up this space. (“Das Kopfskelet der Urodelen.” Morph. Jahrbuch, vol. iii. p. 149). By the expression “arrested growth” not much is said, if at the same time the cause of the arrest is left unstated. But what can be the cause why the whole organization remains stationary at the perennibranchiate stage, the sexual organs only undergoing further development? Surely only that law or force of heredity known by its effects, but obscure with respect to its causes, through which old phyletic stages sometimes suddenly reappear, or in other words, that power through which reversion takes place. It must not be forgotten that all these cases of “larval reproduction” in Amphibians appear suddenly. The present sexually mature form of the Axolotl has not arisen by the sexual maturity gradually receding in the ontogeny from generation to generation, but by the occurrence of single individuals which were sexually mature in the perennibranchiate stage, these having the advantage over the AmblystomÆ in the struggle for existence under changed climatic conditions.

By admitting a reversion, we perfectly well explain why arrest at the perennibranchiate stage can be associated with complete development of the sexual organs; the assumption of an “arrested growth” leaves this combination of characters completely unexplained. Moreover, I am of opinion that the expressions “arrested growth” or “reversion” are of but little importance so long as the matter itself is clear.]

248 See Haeckel’s “Anthropogenie,” p. 449.

249 “Der Ursprung der Wirbelthiere und das Princip des Functionswechsels,” Leipzig, 1875.

250 Bull. Soc. NeuchÂtel. vol. viii. p. 192. Reference given in “Troschel’s Jahresbericht” for 1869.

251 Sitzungsberichte d. math. phys. Klasse der Akad. d. Wiss. zu MÜnchen, 1875. Heft i.

252 Compt. Rend. vol. lxviii. pp. 938 and 939.

253 Archiv f. Naturgeschichte, 1867.

254 Compt. Rend. vol. v. 1870, p. 70.

255 Bull. Soc. NeuchÂtel. vol. viii. p. 192. Reference given in “Troschel’s Jahresbericht” for 1869.

256 [Eng. ed. It was mentioned in the German edition of this work that in the spring of 1876 a female Amblystoma of the Jardin des Plantes in Paris had laid eggs (see Blanchard in the Compt. Rend. 1876, No. 13, p. 716). Whether these eggs were fertile, or whether they developed was not then made known. Thus much was however at the time clear, that even if this had been the case, the reproduction of this Amblystoma would have been only an exceptional occurrence. At that time there were in the Jardin des Plantes Amblystomas which had been kept for more than ten years, and only on one occasion was there a deposition of eggs, and this by only one specimen. That I was correct in speaking of the “sterility” of these Amblystomas in spite of this one exception, is proved by the latest communication from the Jardin des Plantes. We learn from this (Compt. Rend. No. 14, July, 1879, p. 108) that in the years 1877 and 1878 none of the Amblystomas laid any more eggs, although all means were exerted to bring about propagation. In April, 1879, eggs were again laid by one female, and by a second in May. These eggs certainly developed, as did those of 1876, and produced tadpoles. These Amblystomas are therefore not absolutely, but indeed relatively sterile. Whilst the Axolotl propagates regularly and freely every year, this occurs with the Amblystoma but rarely and sparsely. The degree of their sterility can only be approximately established when we know the number of Amblystomas that have since been kept in the Jardin des Plantes. Unfortunately nothing has been said with respect to this.]

257 Origin of Species, 6th ed. p. 252.

258 In plants also reversion forms show sterility in different degrees. Mr. Darwin has called my attention to the fact that the peloric (symmetrical) flowers which occasionally appear as atavistic forms in Corydalis solida are partly sterile and partly fertile. That in other causes of sterility, and above all by bastardizing, the reproductive power is lost in the most varying degrees, has been known since the celebrated observations of KÖlreuter and GÄrtner. [Eng. ed. An Orchid (Catasetum tridentatum) has the sexes separate, and the male flowers (Myanthus barbatus) differ considerably from the female (Monachanthus viridis); besides these, there occurs a form with bisexual flowers which must be considered as a reversion (Cat. tridentatum) and this is always sterile. Darwin, “Fertilization of Orchids,” 2nd ed. p. 199.]

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.

269 I can remember at Upper Engadine a peculiar kind of preserved beef, prepared by simply drying in the air; also the mummification of entire human bodies by drying in the open air, as is practised at Great St. Bernard.

270 “Faune des VertÉbrÉs de la Suisse,” vol. iii. “Histoire Naturelle des Reptiles et des Batraciens.” Geneva, 1873.

271 See Wiedersheim, “Versuch einer gleichenden Anatomie der Salamandrinen.” WÜrzburg, 1875.

272 See GenÉ, “Memorie della Reale Acad. di Torino,” vol. i.

273 Rana esculenta never reaches Alpine regions, this species not having been found higher than 1100 meters. (Fatiot, loc. cit., p. 318.)

274 See also the excellent work upon Mexico by MÜhlenpfordt already quoted, vol. i., pp. 69–76.

275 “Essai politique sur le Royaume de la Nouvelle Espagne,” 1805, p. 291.

276 [The expression made use of by the author, viz. “Diluvialzeit,” would perhaps be more in harmony with the views of English geologists if rendered as the “pluvial period,” thereby indicating the period of excessive rainfall which, according to Mr. Alfred Tylor, succeeded to and was a consequence of the thawing of the great glaciers which accumulated during the last glacial epoch. There is abundant evidence to show that during the latter period glacial action extended in North America at least as far south as Nicaragua. See Belt on “The Glacial Period in North America,” Trans. Nova Scotian Inst. of Nat. Sci. 1866, p. 93, and “The Naturalist in Nicaragua,” pp. 259–265. R.M.]

277 [Eng. ed. A memoir by Samuel Clarke has since been published upon the embryonic development of Amblystoma punctatum, Baird. Baltimore, 1879.]

278 [Eng. ed. See this author’s work, “Das Kopfskelet der Urodelen.” Leipzig, 1877, p. 149.]

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.]

289 [This law has been beautifully applied by Herbert Spencer in order to explain why, with an unlimited supply of food, an organism does not indefinitely increase in size. “Principles of Biology,” vol. i. p. 121–126. R.M.]

290 [Eng. ed. This idea, formerly expressed by me, occurs also in Lange (“Geschichte des Materialismus,” ii. 265), and is there exemplified in a very beautiful manner by illustrations from modern chemistry. Lange compares what I have termed above the “physical constitution” of the organism to the chemical constitution of one of those organic acids which by substitution of single elements may become transformed into more complicated acids, but which, as it were, always undergo “further development” in only one determined and narrowly restricted course. Here, as with the organism, the number of possible variations is very great, but is nevertheless limited, since “what can or cannot arise is determined beforehand by certain hypothetical properties of the molecule.”]

291 “Origin of Species.” 4th German ed., p. 19; 5th English ed., p. 6.

292 [Mr. A.R. Wallace, in his article last referred to, quotes some most valuable measurements of mammals and birds, showing the amount of variation of the different parts. These observations were published by J.A. Allen, in a memoir “On the Mammals and Winter Birds of East Florida,” &c. (Bulletin of the Museum of Comparative Zoology at Harvard College, Cambridge, Mass., vol. ii. No. 3.) R.M.]

293 [See note 142, p. 310. R.M.]

294 “Die Darwin’sche Theorie,” Dorpat, 1875.

295 [A certain number of instances of mimicry are known to occur between species both of which are apparently nauseous. A most able discussion of this difficult problem is given by Fritz MÜller, in the case of the two butterflies Ituna Ilione and Thyridia Megisto, in a paper published in Kosmos, May, 1879 (p. 100). The author shows by mathematical reasoning that such resemblances between protected species can be accounted for by natural selection if we suppose that young birds and other insect persecutors have to learn by experience which species are distasteful and which can be safely devoured. See also Proc. Ent. Soc. 1879, pp. xx-xxix. R.M.]

296 See Haeckel’s “Generelle Morphologie,” ii. 107.

297 “Über die Berechtigung der Darwin’schen Theorie,” Leipzig, 1868.

298 “PopulÄre wissenschaftl. VortrÄge,” vol. ii., Brunswick, 1871, p. 208.

299 “Das Unbewusste vom Standpunkte der Physiologie u. Descendenztheorie,” Berlin, 1872, p. 89. The second edition appeared in 1877, in Von Hartmann’s own name.

300 “Über die Berechtigung,” &c., Leipzig, 1868. In this work will be found briefly laid down the theoretical conception of variability here propounded somewhat more broadly. [In the last edition of the “Origin of Species” Darwin states, with respect to the direct action of the conditions of life as producing variability, that in every case there are two factors, “the nature of the organism and the nature of the conditions.” 6th ed. p. 6. R.M.]

301 [Although hardly necessary to the evolutionist, it may perhaps be well to remind the general reader, that all experiments upon spontaneous generation, or abiogenesis, have hitherto yielded negative results; no life is produced when the proper precautions are taken for excluding atmospheric germs. But although we have so far failed to reproduce in our laboratories the peculiar combination of conditions necessary to endow colloidal organic matter with the property of “vitality,” the consistent evolutionist is bound to believe, from the analogy of the whole of the processes of nature, that at some period of the earth’s history the necessary physical and chemical conditions obtained, and that some simple form or forms of life arose “spontaneously,” i.e. by the operation of natural causes. R.M.]

302 See Haeckel’s “Generelle Morphologie,” vol. ii. p. 203, and Seidlitz, “Die Darwin’sche Theorie,” 1875, p. 92 et seq.

303 [In a recently published work by Dr. Wilhelm Roux this author has attempted to work out the idea of an analogy between the struggle for existence and survival of the fittest in individuals and species, and the struggle for existence and survival of the parts in the individual organism. See “Der Kampf der Theile im Organismus: ein Beitrag zur VervollstÄndigung der mechanischen ZweckmÄssigkeitslehre,” Leipzig, 1881. R.M.]

304 [Eng. ed. Meanwhile it has been shown by Oscar Schmidt that Von Hartmann, under the name of “the Unconscious,” re-invests the old vital force with some portion of its former power. “Die naturwissenschaftlichen Grundlagen der Philosophie des Unbewussten,” Leipzig, 1877, p. 41.]

305 Loc. cit. p. 175.

306 Loc. cit. p. 156.

307 “Über die Cuninen-KnospenÄhren im Magen von Geryonien.” Reprint from “Mittheil. des naturwiss. Vereines,” Graz, 1875.

308 [See Darwin’s “Origin of Species,” 6th ed. pp. 33, 34, and 201–204. R.M.]

309 [Eng. ed. See Kant’s “Allgemeine Naturgeschichte und Theorie des Himmels.”]

310 “Das Unbewusste vom Standpunke der Physiologie und Descendenz-Theorie,” Berlin, 1872, p. 16.

311 [Eng. ed. See Lotze’s “Mikrokosmos,” 1st ed., vol. iii. pp. 477–483.]

312 See Helmholtz’s “PopulÄre wissenschaftl. VortrÄge,” vol. ii., Brunswick, 1872.

313 See also Fr. Vischer’s “Studien Über den Traum. Beilage zur Augsburger Allgem. Zeitung,” April 14th, 1876. Haeckel also includes this idea in his recent essay already quoted, “Die Perigenesis der Plastidule,” Berlin, 1876, p. 38 et seq.

314 See Von Hartmann, loc. cit. p. 158.