Part 19

I believe that I have shown that the theory of selection by no means leads--as is always assumed--to the denial of a teleological Universal Cause and to materialism, and I thereby hope that I have cleared the way for this doctrine, the importance of which it is scarcely possible to over-estimate. Many, and not the most ill-informed, do not get so far as to make an unbiassed examination into the facts, because they are at the outset alarmed by the to them inevitable consequence of the materialistic conception of the universe. Mechanism and teleology do not exclude one another, they are rather in mutual agreement. Without teleology there would be no mechanism, but only a confusion of crude forces; and without mechanism there would be no teleology, for how could the latter otherwise effect its purpose?[314]

Von Hartmann correctly says:--“The most complete mechanism conceivable is likewise the most completely conceivable teleology.” We may thus represent the phenomenal universe as such a completely conceivable mechanism. With this conception vanish all apprehensions that the new views would cause man to lose the best that he possesses--morality and purely human spiritual culture. He who, with Von Baer, considers the laws of nature as the “permanent expressions of the will of a creative principle,” will clearly perceive that a further advance in the knowledge of these laws need not divert man from the path of increasing improvement, but must further him in this course--that the knowledge of truth, whatever may be its purport, cannot possibly be considered a backward step. Let us take our stand boldly on the ground of new knowledge, and accept the direct consequences thereof, and we shall not be obliged to give up either morality or the comforting conviction of being part of an harmonious world, as a necessary member capable of development and perfection.

Any other mode of interference by a directive teleological power in the processes of the universe than by the appointment of the forces producing them, is however, at least to the naturalist, inadmissible. We are still far removed from completely understanding the mechanism by means of which the organic world is evoked--we still find ourselves at the very beginning of knowledge. We are, however, already convinced that both the organic and the inorganic worlds are dependent only upon mechanical forces, for to this conclusion we are led, not only by the results of investigators who have restricted themselves to limited provinces, but also by the most general considerations. But although the force of these arguments may not be acknowledged, and although one might maintain that the inductional proofs against the existence of a “phyletic vital force” have been directed only against points of detail, or have never been completely demonstrated, _i.e._ for all points, it must nevertheless be conceded, that for the naturalist the mechanical conception of Nature is the only one possible--that he is not at all justified in abandoning this view so long as the interference of teleological forces _in the course_ of the processes of organic development has not been demonstrated to him. Thus, it will not be immaterial whether a conception of Nature which to many seems inevitable is consistent with the idea of universal design, or a final directive universal principle, since the value which we may attach to our own lives and aims, essentially depends thereon. The final and main result of this essay will thus be found in the attempted demonstration that the mechanical conception of Nature very well admits of being united with a teleological conception of the Universe.

THE END.

FOOTNOTES

[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.