PROTECTIVE COLOURING AND MIMICRY. I should like to have been able to give a lengthy note on this most interesting subject, but had very few opportunities of studying even the cases which came under my notice. Among the more conspicuous instances of protective colouring, I may mention the genus Ageronia of butterflies. These invariably rest, head downwards, with their wings fully expanded, and flattened out on the lichen-covered trunks of the lofty palm trees. These butterflies are plentiful at Rio de Janeiro, and, though a large insect-some two inches across the wings-may yet be passed unnoticed at the distance of a few yards, so closely do they simulate the lichens. The genus Siderone is also noteworthy. They always rest, with wings folded over their bodies, on branchlets; the markings and colouring of the under side of the wings resembling exactly dry brown or yellow leaves. The species S. Isidora (Cram.) has also two clear spots on the upper wings, mimicking holes made by insects. Referring to the mimicry of moths, Mr. Bates says, "Several times I shot by mistake a humming-bird hawk-moth instead of a bird." "Along the narrow paths in the forests an immense number of clear-winged moths are found in the daytime, mostly coloured like wasps, bees, ichneumon flies, and other hymenopterous insects. Some species of the same family have opaque wings, and wear the livery of different species of beetles; these hold their wings in repose, in a closed position over their bodies, so that they look like the wing-cases of the beetles they decep tively imitate." † from all eternity, it would be a superfluous hypothesis. . . . It is, then, much more simple and much more natural to suppose that the universe has always existed, that the unlimited material which composes it has always been in motion, that it has ever eternally metamorphosed itself." On reading this, one thought is borne on the mind, that word "God shall send them strong delusion, that they should believe a lie" (2 Thess. ii. 11). Domine dirige nos in viam veritatis. This note, with the exception of the last sentence, was inserted in the Morning Post, January 6, 1886. * "The Naturalist on the River Amazons," vol. i. pp. 181, 105. Mr. Thomas Belt, in "The Naturalist in Nicaragua," gives instances of The axiom that the mimicking insect should be rarer than its model is not always carried out, e.g. the Euterpe tereas (Pierina), which copies the Papilio nephalion. It is often common while the latter is rare. The Colanis Julia (Nymphalina) is far commoner than the deceptively similar but smaller Eueides aliphera (Heliconine). * I must next refer to the sub-families Danaïnæ and Heliconinæ, in which mimicry among various genera is the more remarkable, as it is not, apparently, necessary for protective purposes. Dr. Fritz Müller remarks † that "the Ithomiæ of the Amazons and their allies, e.g. Mechanitis, as Bates observes, are imitated by so many butterflies belonging to the most different families, that they may certainly be correctly regarded as quite safe from the pursuit of birds on account of their distastefulness. . . . Among the numerous mimics are swarms of Acræa thalia. The strong-smelling Eueides Isabella and Heliconius eucrate have either individually or together acquired a resemblance to Mechanitis lysimnia, which insect to us is inodorous; and amongst the numerous butterflies which sufficiently resemble the three above-named species as to be occasionally mistaken for them are species belonging to the Ithomia group (Melinaa), and to the true Danaïdes (Lycorea). Thyridia and Ituna (Danaïdæ) both belong to the class of cases in which the two species which resemble one another appear to be equally well protected by distastefulness. The former belongs to the Ithomia group, the distastefulness of which has been referred to; and the latter to the Danaïdes, which play the same part as models of imitating species in the Old World as the Ithomiæ in the New. They appear even after death to defy the ravages of time and the attacks of mites, etc., by virtue of their distastefulness." Mr. Bates, in discussing this paper, said, "The numerous cases where species which are themselves apparently protected by their offensive secretions, evidently mimic other species similarly protected, still form a great stumbling-block; the excessive complexity stinging ants being closely copied in form and movement by spiders, Hemiptera and Coleoptera. I have an example in the genus Mutilla, which is exactly imitated by the beetle Cyphus Linnæi, Sch. "Proc. Ent. Soc.," 1879, p. xx., etc. ↑ Ibid., p. xxv., et seq. of the question is evident to all who read Dr. Fritz Müller's writings on the subject. . . . The phenomena with regard to the Heliconidæ are these: In tropical South America a numerous series of gaily coloured butterflies and moths, of very different families, which occur in abundance in almost every locality a naturalist may visit, are found to change their lines and markings together, as if by the touch of an enchanter's wand, at every few hundred miles, the distance being shorter near the eastern slopes of the Andes than nearer the Atlantic. So close is the accord of some halfdozen species (of widely different genera) in each change, that he [Mr. Bates] had seen them in large collections classed and named respectively as one species." Ituna and Lycorea are connecting links between the Danaides and the Ithomiæ. Among the beetles (Coleoptera), I may mention the genus Chlamys, of which Mr. Bates says,* it consists "of small beetles of a cubical shape and grotesque appearance, the upper surface of their bodies being studded with tubercles. They look like anything rather than insects; some of them are an exact imitation of the pellets of excreta of caterpillars on leaves" (e.g. Chlamys Nattereri, Kollar; † C. arcula, † Germ., etc.). "Others have a deceptive likeness to small flower-buds, galls, and other vegetable excrescences; while some large kinds are like fragments of metallic ore" (e.g. Poropleura bacca,‡ Kirby ; P. monstrosa,‡ Oliv.). “They are very sluggish in their motions, and live in the most exposed situations on the surfaces of leaves. Their curious shapes are, therefore, no doubt so many disguises to protect them from the keen eyes of insectivorous birds and lizards. "A nearly allied group, Lamprosomas" (of which I have several species), "have perfectly smooth convex bodies; these glitter like precious stones on the foliage, and seem to be protected by the excessive hardness of their integuments. . . . "The Chlamydes are almost confined to the warmer parts of America, and the species, although extremely numerous (about three hundred are known in collections), are nearly all very rare. "It is worthy of note that mimicking insects are very generally * "The Naturalist on the River Amazons," vol. i. pp. 346, 347. of great scarcity; that is, few examples of each species occur in the places where they are found, and they constitute groups which. are remarkable for the strongly marked diversity and limited ranges of their species." I took a beautiful weevil-Heilipus trachypterus (Germ.)-in Minas, whose cream-coloured and black elytra, studded with rugosities or tubercles, resemble the lichens of the tree trunks. I also found some sand-beetles, which were protectively coloured. Many other beetles, which would not be considered to be thus guarded against their foes, are found to be so in their native haunts, from resembling either a black dead leaf or a berry, etc. I may also mention the grasshoppers. Some long and thin, exactly simulating blades of grass; others larger, some two inches long by half an inch thick. One specimen that I have is Steirodon citrifolium (Serv.). These are exactly similar to green leaves. There is also the curious group of Phasmidæ, or stick-insects. For further details I would refer to Mr. A. R. Wallace's book, "Tropical Nature ;" also to a very interesting essay on " Protective Resemblances and Mimicry in Insects," by Roland Trimen, F.R.S., in the February and March numbers of the Entomologist for 1885; also a paper on "The Habits of the Butterflies of the Amazon Valley," by A. R. Wallace. There is no doubt that insects are endowed with protective. colouring and mimicry to assist those which are edible in avoiding their innumerable foes, while the gaudily coloured genera may freely display themselves, as, being unpalatable, they have no need of concealment. The theory of these phenomena has been so frequently discussed that I must do no more than allude to the subject; but I am compelled to confess that I cannot agree with the hypothesis of the gradual development of such protection; not only because I fail to comprehend how, during the necessarily lengthened period when such an advantageous condition was being produced, the individuals could derive any benefit, but also especially on account of the dangerous deductions that have been drawn from the theory of evolution. It is unnecessary to detail all the pro and con arguments which *Trans. Entom. Soc.," 1853. have been adduced almost ad nauseam; but I earnestly recommend all students to examine the theories of natural selection and survival of the fittest, together with the extravagant demands of their exponents, and to consider whether the opposing theory of special creation may not, at least, be as tenable and workable. How can men believe in, or even consider as possible, the calmly propounded theories of evolutionists who have gone beyond Darwin, and who present, as their well-weighed conclusions, the statement that every existing organism has evolved by chance from one primordial germ, and that the first particle of animated matter was "the fortuitous concourse of atoms "? At least, the yawning and insuperable gulfs which exist between certain families cannot, to my mind, be bridged over by any theory but the axiom of special creations, at certain periods, however remote. Mr. Darwin has said, "It is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by Nature." Therefore I plead again for moderation in the expression of ideas, both from scientists and theologians. But I contend that, at least, we must start with the fundamental doctrine of a Supreme Being, Who is, by infinite condescension, in personal relation to every one, and Who, while He makes wonderful revelations of His power and omnipresence in the natural world-every movement of which is the object of His care-reveals Himself in a far more transcendent and miraculous manner to man, who is conformed to His likeness, and "in Him we live, and move, and have our being." I conclude with an extract from Professor P. J. van Beneden's work on "Animal Parasites : "All the mutual adaptations are pre-arranged, and, as far as we are concerned, we cannot divest ourselves of the idea that the earth has been prepared successively for plants, animals, and man. When the Creator first elaborated matter, He had evidently that being in view who was intended at some future day to raise his thoughts to Him and do Him homage. . . . The artist who tempers the clay from which to make his model has already conceived in his mind the statue which he is about to produce. * "Descent of Man," vol. i. p. 3. |