The Zoologist/4th series, vol 3 (1899)/Issue 697/Biological Suggestions. Mimicry, Distant

by William Lucas Distant

 

THE ZOOLOGIST

 

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No. 697.— July, 1899.

 

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BIOLOGICAL SUGGESTIONS.
MIMICRY.

By W. L. Distant.

Part I.

 

"Evidence has three degrees of force: demonstration, probability, plausibility."—Matthew Arnold.
"The essence of originality is not that it be new."—Carlyle.
"Nature suffers nothing to remain in her kingdoms which cannot help itself."—Emerson.

 

If, as we have before suggested, our only clue to the original, or even primitive, colouration of animals is lost and buried in the records of the geological past, in which we find structure—scantily and often confined to typical portions—but of colour nothing,^[1] a much larger field is open to the palaeontologist who seeks for the origin of that animal structure which is so often alike described under the terms of "protective resemblance" and "mimicry." Friends and foes of those theories too frequently—both for attack and defence—conceive the wonderful protective disguises in nature as having been evolved during the time of present natural conditions;^[2] whereas we should think not of years but of geological epochs, for time is only an imaginary quantity, alike useful to the mathematician and historian, a result of expressing the term of our short lives. Thus we may seek to multiply the years of our fugitive existence into a product which shall represent the limits of an unknown past, whilst we can only imagine space by the equivalent of time.

We have already ventured some suggestions on the subject of assimilative colouration, and we now approach a different class of phenomena, where the resemblance is not of colour alone, but also frequently of structure, by which animals exhibit a close resemblance to some inanimate object, and to which the term "Protective Imitation of Particular Objects" has been aptly proposed by Mr. Wallace.^[3] One of the most striking examples is found in the Orthopterous family Phasmidæ,^[4] and in what are generally known as the "Walking-stick insects." To use the graphic and accurate description of Mr. Wallace:—"Some of these are a foot long, and as thick as one's finger, and their whole colouring, form, rugosity, and the arrangement of the head, legs, and antennæ, are such as to render them absolutely identical in appearance with dead sticks. They hang loosely about shrubs in the forest, and have the extraordinary habit of stretching out their legs unsymmetrically, so as to render the deception more complete."^[5] Mr. Wallace travelled both in the western and eastern tropics. The late Prof. Drummond records similar impressions in Africa:—"On finding one of these insects, I have often cut a small branch from an adjoining tree, and laid the two side by side for comparison; and when both are partly concealed by the hands so as to show only the part of the insect's body which is free from limbs, it is impossible to tell the one from the other. The very joints of the legs in these forms are knobbed to represent nodes, and the characteristic attitudes of the insects are all such as to sustain the deception."^[6] Every writer, in fact, who approaches the subject of animal disguises, whether evolutionist or not, quotes these insects as one of the strongest illustrations he can find, and with ample warrant, for we may take these "Stick-insects" as affording a typical instance of what is understood as protective resemblance. The protection, however, cannot be complete, for Wallace found the stomachs of certain Cuckoos full of them.^[7]

Now, it is a general postulate that this highly imitative and protected form is due to the action of "natural selection," acting on some incipient and original element of variation. As Mr. Bates observed:—"Natural selection having, from the first, favoured the species which offered variation in these parts, the tendency to variability has become perpetuated by inheritance."^[8] Or, as Mr. Darwin put it:—"Assuming that an insect originally happened to resemble in some degree a dead twig or a decayed leaf, and that it varied slightly in many ways, then all the variations which rendered the insect at all more like any such object, and thus favoured its escape, would be preserved, whilst other variations would be neglected and ultimately lost; or, if they rendered the insect at all less like the imitated object, they would be eliminated."^[9] We should therefore expect, if a perfect geological record could unfold the ancestry of these insects, to trace a gradual evolution of form for protective purposes under the influence of natural selection. Such an investigation has been attempted, and such a result apparently obtained by Mr. Cameron, in his search for "the origin and purpose of the horns and antlers of ruminants." He concludes "that the horns and antlers of ruminants are the result of a defensive adjustment in biological answer to carnivorous teeth and claws, and consequent upon the relations of destroyer and destroyed which obtained between carnivores and ungulates throughout Tertiary time.... Their historical appearance in the Miocene age of the Tertiary period is contemporaneous with a vast extinction of hornless ungulate families, and their subsequent development in an ascending scale corresponds with the gradual thinning out of unarmed ungulate genera, and the gradually increasing destructive pressure upon those, whether armed or unarmed, that survived. Their evident loss of calibre since palæolithic times may be traced chiefly to the coming of man with missile weapons, which, in altering the character of the destroying agency, discounted the value of cranial armature in the struggle for life."^[10]

It is a remarkable fact with these Phasmidæ that giant forms are said to have existed even in the Carboniferous fauna. Among other Orthoptera belonging to that era were "the giant Walking-sticks recently brought to light from the coal-measures of France, the Titanophasma fayoli, which measure in length (in one specimen) upwards of twelve inches, and are therefore, by linear measure, very nearly the largest of recent as well as fossil insects."^[11] It is necessary, however, to observe that much caution must be exercised in the identification of these fossil remains. Dr. Sharp is at least sceptical, for he writes:—"In the Carboniferous layers of the Palæzoic epoch there are found remains of gigantic insects that may possibly be connected with our living Phasmidæ."^[12] The same writer, however, has subsequently given a less undecided opinion: "Phasmidæ are insects of extreme interest; they appear to be the nearest living representatives of an insect fauna that was predominant in the Carboniferous epoch."^[13] Brongniart and Scudder have proposed a distinct family—Protophasmidæ—for these fossil remains, though Scudder's "restoration" of T. fayoli is perhaps, and necessarily, somewhat imaginary. Mr. Comstock maintains that "we must turn to the Carboniferous as the earliest epoch from which we have data to base our conclusions regarding the structure of the primitive insect wings";^[14] whilst Huxley believed that "the Carboniferous Insecta and Arachnida are neither less specialized, nor more embryonic, than those that now live."^[15]

If, however, we suppose, as we may reasonably do, that these Carboniferous Phasmidæ must have been protected forms of insect life at that period—for it is by their peculiar structure that the fossil remains are recognized—the imitative resemblance would also have a different meaning and a diverse reference to what now obtains. Respecting fossil Cockroaches, Mr. Scudder states:—"The first Cockroach wing ever described was first described as a fern leaf, and in all, or nearly all, the localities where their remains have been found they are associated with fern leaves in immense abundance. While searching for their remains in the Permian deposits at Carsville, I was much struck by this resemblance, and was repeatedly obliged to use the glass to determine whether it was the wing of a Cockroach or the frond of a fern I had uncovered, and the instances are not rare where they agree completely in size. The general distribution of the nervures is to cursory view the same in each, and the form is often nearly identical."^[16] The flora of the Carboniferous era was very different to that of the present epoch. The mighty forests of gigantic horse-tails, club-mosses, and tree-ferns replaced or anticipated the jungles and woods of to-day; and, as Haeckel truly observes:—"It is difficult for us to form any idea of the very peculiar nature of those gloomy palæolithic fern-forests, in which the whole of the gay abundance of flowers of our present flora was entirely wanting, and which were not enlivened by any bird or mammal."^[17] Prof. Geikie describes it as "marked by a singular monotony of character all over the world from the Equator into the Arctic Circle, the same genera, and sometimes even the same species, appearing to have ranged over the whole surface of the globe. It consisted almost entirely of vascular cryptogams, and pre-eminently of Equisetaceæ, Lycopodiaceæ, and Ferns. Though referable to existing groups, the plants presented many remarkable differences from their living representatives. In particular, save in the case of the ferns, they much exceeded in size any forms of the present vegetable world to which they can be assimilated. Our modern horse-tails had their allies in huge trees among the Carboniferous jungles, and the familiar club-moss of our hills, now a low-creeping plant, was represented by tall-stemmed Lepidodendra that rose fifty feet or more into the air. The ferns, however, present no such contrast to forms still living. On the contrary, they often recall modern genera, which they resemble not merely in general aspect, but even in their circinnate vernation and fructification. With the exception of a few tree-ferns, they seem to have been all low-growing plants, and perhaps were to some extent epiphytic upon the larger vegetation of the lagoons."^[18] Now, if we keep in mind this description of the very different flora that then existed, we cannot help recognizing the fact that these Stick-insects would either have a totally different relation to the trunks of those tree-ferns to what they bear to the branches and twigs of trees as known to ourselves, or that they then—as is more probable—by a difference of form to their present descendants, assimilated to their then environment.

Again, the more ancient existence of the Phasmidæ, prior to the Carboniferous epoch, is implied, for it is impossible to imagine on any evolutionary principle that these giant insects came suddenly into existence at that era, especially if, as we believe, their imitative structure is due to the action of natural selection. In that case there must have been antecedently less specialized forms, less imitative structure. "Considering the abundance of Walking-sticks in Paleozoic rocks, the absence of their remains from Mesozoic strata is rather remarkable."^[19] But the difficulties in the clear conception of this question do not end here. As early as this Carboniferous epoch, these insects appear to have possessed what we naturally consider as a protected or imitative structure, and this view is inconceivable without the antecedent proposition that their enemies then existed, and that the imitative guise was that of the oft-devoured against the would-be-devourer. But it is affirmed that Lizards do not appear before the Permian epoch,^[20] birds as certainly not before the Jurassic^[21] or perhaps the Triassic formation. "It is quite possible that birds existed during the Triassic period, but at present there is no proof of it."^[22] And if these facts were taken as final, then an insuperable difficulty would exist as to the structure of these Phasmidæ being due to a gradually acquired protective character. But the same argument applies to these ancient Lizards as to our Carboniferous Stick-insects. As Huxley remarks, "These Permian Lizards differ astonishingly little from the Lizards which exist at the present day"; and again, "It is perfectly clear that if our palæontological collections are to be taken, even approximately, as an adequate representation of all the forms of animals that have ever lived, and if the record furnished by the known series of beds of stratified rocks covers the whole series of events which constitute the history of life on the globe, such a fact as this directly contravenes the hypothesis of evolution; because this hypothesis postulates that the existence of every form must have been preceded by that of some other form different from it."^[23] If we study the records of animals that have lived at a former period of the world's history, but have at present no representatives, we shall find,—to again quote our previous authority, "Among the Mammalia and birds there are none (orders) extinct; but when we come to the reptiles there is a most wonderful thing: out of the eight orders or thereabouts which you can make among reptiles one-half are extinct."^[24] Amphibia, however, certainly existed, and were apparently abundant in the Carboniferous age; and, as Mr. Thomson remarks, "the food of adult amphibians usually consists of insects, slugs, and worms."^[25] We may surmise that many were arboreal in their habits, and these, before the advent of the true reptiles and birds, must have constituted the principal insect enemies. We must also recollect that the Pterodactyles, or Flying Dragons, during the long reptilian period, "played the rôle of the bats and birds of the present day."^[26] The imperfection of the geological record is, however, no argument against evolution, though it seems strange it has not even been made of much more use by some opponents. The struggle for life is an ancient one, but the combatants have not always been the same. In Pliocene times, as Prof. Owen has stated, "Bats, Moles, and Shrews were then, as now, the forms that preyed upon the insect world in this island."^[27] The number of mammals which devour insects seem sometimes overlooked, and this fact can be easily realized by looking through the pages of any good treatise on the Mammalia, and tabulating the nature of the food used by the different animals. For the purpose of the present discussion it should be remembered, as remarked by Mr. W.L. Sclater, that the conclusion is more than probable "that before the commencement of the Tertiary epoch the whole world was, so far as is at present known, inhabited by small insignificant mammals distinctly allied to the marsupials."^[28]

Perhaps one of the inevitable faiths is that of the man of science who neither disguises the necessity of the halt, nor disbelieves in the certainty of the forward march, and these Carboniferous Phasmidæ almost prove the pre-existence of the Permian reptiles and the Jurassic birds.^[29] If these stick-insects really possessed, and did not derive their imitative structure for protective purposes, then the whole theory of "Protective Resemblance" among insects may go to the wall. The need of protection must undoubtedly have existed in Carboniferous times, if this hypothesis is to stand, and such a view helps to prove, as Huxley has already urged, a pre-Permian existence for reptiles,^[30] and, we may add, a greater antiquity also for birds, both of which, we may presume, were, as now, great enemies to insect-life.

The only other explanation—known to the writer—which has been offered to account for the peculiar structure of these Stick-insects, is one proposed by the late Prof. Karl Semper, which would have received additional emphasis had that naturalist been aware (he at least does not allude to the fact) of the Phasma being found as a Carboniferous fossil. Prof. Semper's proposition is that the structure denotes what has been styled "'Larva-forms,' a name given to all animals which possess the characters of the larvæ of other species, and are nevertheless capable of sexual reproduction." The opinion is amplified by the following explanatory illustration:—"Thus species of the same genera, perhaps even the very same species, in our damp and cold climate, do not produce a new generation till they are fully grown; while in the dry warm region of the Mediterranean they have produced two generations before they are fully grown."^[31] This would be somewhat on a line with the suggestion we have made that most unicolorous animals are survivals from an original assimilative colouration, and have thus survived by being in harmony with their surroundings, and thus coming under the sanction and perpetuating influence of natural selection. On this theory the Stick-insect would be merely the survival of an ancient "Larva-form" which fulfilled the same purpose, and thus also came down to us unchanged under the fostering care of the same selective influence. But Prof. Semper, further speculating on the fact of these insects comprising winged and wingless forms, is inclined to account for the same by the "optimum temperature"^[32] under which the eggs have been matured. A fuller knowledge of these Phasmidæ will scarcely support this proposition. What we find is a most graduated and complicated connection between the winged and wingless forms. The late Prof. Westwood, a most determined opponent to evolution in any shape or form, contributed—as so many other opponents have done before and since—unconscious testimony to the same, in an artificial classification which he proposed for the family.^[33] As summarized by Mr. Bates:—"The groundwork of this classification is the gradation or development of the wings from genus to genus. Thus it begins with those genera which are wingless in both sexes, these forming one Division, and passes through those in which the males are winged and the females wingless, or in which the wings are rudimentary, to the genera which have well-formed wings in both sexes—the whole of the latter forming the second Division. The wingless series commences with those forms which have much abbreviated antennæ and very attenuated bodies, and progresses to those having long setiform antennæ, or bodies of much more compact structure. The winged series progresses gradually from those genera in which the upper and lower wings are either rudimentary, or developed in one sex only, to those in which they exist in both sexes (but the upper wings of extreme shortness), ending at length with genera in which both upper and lower wings have become elongated in an approach to due proportion."^[34] This complicated classification, which expresses the difficulties and intricacies of evolution in every sentence, naturally sometimes fails in the details of its own arrangement, but is sufficient to throw more than grave doubts on the explanation offered by Prof. Semper. The consideration of the present knowledge applicable to these Phasmidæ appears to warrant the following conclusions:—

1. The Walking-stick insects are usually considered by naturalists to be undoubted examples of "Protective Resemblance," due to a process of "Natural Selection."

2. If they are found with a somewhat similar structure in the Carboniferous fauna, they must therefore be the result of a previous course of evolution.^[35]

3. Reptiles and birds, well-known insect enemies, are generally considered as posterior to the Carboniferous epoch.

4. But as the Permian reptiles were fully developed as we know them now, they must have had an earlier and less differentiated structure; the same suggestion being applicable to the Jurassic birds.

5. The presence of the imitative Phasmidæ in the Carboniferous epoch implies the existence of enemies, probably reptiles, and possibly a transitional form of bird-life.

Good cause is shown why we should seek in past geological epochs for the earliest traces of protective resemblances and mimicry, for the absence of observed attack in the present time does not disprove a great danger and want of protection in the dim eras of the past. "In studying protective resemblance and mimicry among living animals, the exceedingly common occurrence of these phenomena has often forced upon me the conclusion that they have not been limited in their scope to recent times, but must have existed in past epochs, and even, to some extent at least, in very remote epochs."^[36] When gadflies are about, the Ox "seems to be seized with an unreasoning paroxysm of fear." "In modern times the gadfly merely causes some fear and a little discomfort to an animal, and some loss of money and temper to its owner when he finds that the hide has been perforated, and is therefore held cheap by the tanner. But there must have been occasions when the war between gadflies and cattle was a much more serious affair. So strongly marked a protective instinct can only have been produced at a time when the very existence of the species was threatened by parasites of this order."^[37] Sir Charles Lyell, as early as 1836, and before much had been thought or expressed on the subject—for Darwin had not then returned from his epoch-making voyage—appears to have had clear conception of the phenomena, though based on very different philosophical views to those he embraced and enunciated later on. In a letter to Sir John Herschel, he advances probable causes that may aid a species' duration in time. "Now, if it be an insect, it may be made in one of its transformations to resemble a dead stick, or a lichen, or a stone, so as to be less easily found by its enemies; or, if this would make it too strong, an occasional variety of the species may have this advantage conferred upon it; or, if this would be still too much, one sex of a certain variety. Probably there is scarcely a dash of colour on the wing or body of which the choice would be quite arbitrary, or what might not affect its duration for thousands of years. I have been told that the leaf-like expansions of the abdomen and thighs of a certain Brazilian Mantis turn from green to yellow as autumn advances, together with the leaves of the plants among which it seeks for its prey. Now, if species come in succession, such contrivances must sometimes be made, and such relations predetermined between species, as the Mantis, for example, and plants not then existing, but which it was foreseen would exist together with some particular climate at a given time."^[38]

If we were referring to insects in general, and not to these Phasmidæ in particular, we should not lay such stress on the probability of their enemies in the past being largely reptiles^[39] and birds. No one who has collected insects beneath an electric light, as I have frequently done at Pretoria, attended in the same pursuit with the shadowy rushes of Bats above, and a host of patient Batrachians beneath, can doubt what wholesale insect destroyers are found in the ranks of the Chiroptera and Amphibia. But although I have found all orders of insects attracted by these lights, including Orthoptera—comprising Mantidæ, Achetidæ, Forficulidæ, Blattidæ, Gryllidæ, and Locustidæ—I personally never met with any representatives of the Phasmidæ, though of course these insects may also prove to be nocturnal in their habits, and to be also attacked by Bats. But as these animals have not been traced further back than Eocene times, we can scarcely regard them as having proved enemies to the Carboniferous Stick-insects. With the Amphibia the case is different, and, according to the late Prof. Martin Duncan, "the most ancient Amphibia appear to have first lived during the Carboniferous age, and all were tailed, had pleurodent teeth, simple in their construction.... Some were Lizard-like and others were serpentiform.... They are the Microsauria (Dawson), and the genera Hylerpeton (Owen), Hylonomus (Dawson), Brachydices (Cope), and Ophiderpeton (Huxley) are typical."^[40] Here we have a host of contemporary Carboniferous enemies who may indeed have proved a great trial to the existence of unprotected Phasmidæ, and who may synchronously with the evolution of themselves have indirectly caused or induced a protective evolution in the structural form of these insects, by the mutual interdependence in those relations of cause and effect which can be expressed by the well-known appellation "natural selection." And so, for the sake of the argument, dismissing even the agency of either reptiles or birds, we still have abundant reason for believing that, though the protective resemblance of these Phasmidæ was already acquired in Carboniferous times, the presence of Amphibia in an evolutionary sense is quite sufficient to account for it. This prompts two reflections: one that we ought to look a long way back for the origins of these protective and mimetic guises; and the other, that we may reasonably hope to find them. The present attitude of many champions of the cause, who seek to find, or to invent, present factors for producing these phenomena, seems fraught with peril for the whole theory; and with the same weariness and perseverance with which the original promulgators thought out the doctrine, we must go on searching for further proofs, which will necessitate our appealing to the Cæsar of the past—the ever-growing science of palaeontology.^[41] In this domain many similar problems still remain unsolved. In the old red sandstone of Scotland are abundant remains of fishes, such as Osteolepis, but the reason why these and so many other ancient creatures were enveloped or armed in coats of mail, or rather the antecedent factors provocative of the evolution, has not yet been discovered.

In taking leave of these protected Phasmidæ we will record two—and only two—testimonies to their imitative deception, one old and the other modern.

When Pigafetta visited the island of Palawan, he saw many wonders, and described one as follows. There "are found certain trees, the leaves of which when they fall are animated and walk. They are like the leaves of the mulberry tree, but not so long; they have the leaf-stalk short and pointed, and near the leaf-stalk they have on each side two feet. If they are touched they escape, but if crushed they do not give out blood. I kept one for nine days in a box. When I opened it, the leaf went round the box."^[42] This may be taken as a strong, and, what is more, then unsolicitated, testimony to the efficacy of protective resemblance among insects. Linnæus, doubtless with the true inwardness in his mind, wrote:—"Anyone who happens to see, in the Indian woods, the falling leaves of trees apparently become alive, and creep upon the ground."^[43]

Our second illustration is from the pen of that keen and excellent observer, Mr. Belt:—"I was much surprised with the behaviour of a green leaf-like Locust. This insect stood immovably among a host of Ants, many of which ran over its legs without ever discovering there was food within their reach. So fixed was its instinctive knowledge that its safety depended on its immovability, that it allowed me to pick it up and replace it among the Ants without making a single effort to escape. This species closely resembles a green leaf."^[44]

 

If we consider it unsafe to predicate the colours of animals in past geological eras on the basis of their present hues and markings, it is as equally unwarranted to conclude that the nature of their food was the same then as now. And therefore we must be prepared to admit that probably insects had enemies in the past which are now only known as non-insectivorous, and the same suggestion will apply to other animals. This line of argument is prompted by the many recorded examples of wild and domesticated animals who have taken to a food totally different to that of other members of their family and even genus. It is necessary to give some examples, for, if not overlooked, such facts seem little taken into consideration. At the same time only some among many instances can be quoted.

Mammals.—Macacus cynomolgus, a well-known Monkey of Malasia, according to Sir Arthur Phayre, frequents salt water creeks and devours shell-fish, thus being known among naturalists as "the Crab-eating Macaque." "A l'égard des jeunes oiseaux, le gorille et le chimpanzé font preuve d'une telle voracité qu'ils avalent leur proie sans la déplumer."^[45] Bonvalot narrates that small Thibetan Horses "feed on raw flesh, as we have seen with our own eyes."^[46] Sandeman, writing of South Africa, observes that, though many of the Horses never get over their dislike to the smell of blood, he possessed one that rather liked it, and found him one day "licking the bleeding carcass of a newly-skinned Bôk."^[47] It has been stated that "African Horses very commonly eat their own dung; and numbers have been destroyed in consequence of taking into the stomach vast quantities of flinty sand."^[48] Dr. Stockwell, writing from Ontario, Canada, states:—"At certain points on the shores of Lake Huron the soil is quite sterile,—that is, very sandy,—and those who attempt to cultivate frequently use as compost fish caught in seines from the lake. These fish are chiefly Suckers (Catastomidæ), Dog-fish (Amiidæ), Herrings and Lesser Mackinaw Trout (Coregonus artedi, Le Sueur, and Salvelinus, both of the Salmonidæ). Frequently the maize which is planted in hills along with fish fails to exhibit a vigorous growth when cattle are turned in to graze them." But not only the cattle are attracted by the fish. "Some twenty years since a gentleman in the States imported a herd of a hundred and eighty Horses from the Shetlands, and was obliged to keep them for some time close to tide water, where they could get salt sedge grass and a diet of fish, such as they had been accustomed to. Gradually they were weaned to feed upon hay and grain. I have repeatedly seen Horses from this herd, or their descendants, if offered a piece of raw fish devour it with the greatest gusto."^[49] Other animals embrace a fish diet with avidity. In Kamschatka during the long winters, when it is difficult to procure food of any kind, there is a consequent necessity of fish as an article of diet for almost every living creature in the settlements—"the Cows and Horses even not excepted."^[50] In the same country when the streams are surcharged with fish, the Bears "live entirely upon Salmon. Later, when this diet fails them, they take to berries, upon which they live until the time of hybernation."^[51] "There are indeed but few animals, apparently, which do not live on Salmon in Kamschatka."^[52] Gilbert White has remarked "on the violent fondness for fish" possessed by common house Cats, when, "of all quadrupeds, Cats are the least disposed towards water, and will not, when they can avoid it, deign to wet a foot, much less to plunge into that element."^[53] To this Mr. Harting adds a note:—"It is generally supposed that Otters live exclusively on fish, but such is not invariably the case. They are carnivorous as well as piscivorous, and have been known to eat Ducks and Teal, and, while in confinement, young Pigeons. Frogs form part of their bill of fare, and even Mussels at times furnish food to these animals."^[54] The Common Armadillo (Dasypus villosus) is an adroit capturer of Mice, and Mr. Hudson "frequently found their stomachs stuffed with clover, and, stranger still, with the large hard grains of the maize swallowed entire."^[55] "The Zoo Otters have conformed to the universal tendency to extend the range of diet by eating shipbiscuit as well as fish."^[56] According to Mr. Lydekker, Otters have been known when hard pressed during winter to make occasional raids on the farmyard, where they have been asserted not only to kill poultry, but also young Lambs and Pigs.^[57] As stated by Mr. Dimmock, "Adolph Müller mentions that his Cat regularly hunted at twilight the moths, chiefly Noctuidæ, in his garden" ('Zool. Garten,' Aug. 1880, jahr. 21, pp. 253–4). He also states, from his own experience: "About 1870 I had a Cat that nearly every hot afternoon in summer and autumn caught Grasshoppers (Caloptenus and Œdipoda), and brought me her insect captures alive before eating them, with as much pride as if she had taken Mice or birds." He also noticed "several Cats capture and eat beetles of the genera Lachnosterna and Prionus; the odour of the beetles of the latter genus seems sufficiently pungent and repulsive to drive away Cats, since they dislike most pungent odours; but I have seen two Cats that apparently regarded Prionus as a delicacy, for they would eat dead, mutilated, sometimes half-decayed beetles of this genus which they found about the yard."^[58] Of the North American Mustela vison Darwin relates, "During the summer this animal dives for and preys on fish, but during the long winter it leaves the frozen waters, and preys, like other Polecats, on Mice and land animals."^[59] The Bactrian Camel (Camelus bactrianus), instead of confining itself to a strictly vegetable diet, will, according to Prejevalski, when pressed by hunger, readily devour almost anything that it may come across, including felt blankets, bones and skins of animals, flesh, and fish.^[60] That prolific pest in Australia—the Rabbit—is now said to have learned to live and thrive on bark and the twigs of bushes, and even to have developed the power of getting up trees^[61] in search of food, going up as high as eight feet, using their teeth to climb with.^[62] When the Hamsters (Cricetus frumentarius) issue in the spring from the burrows in which they have have passed their winter hybernation, "they devour ravenously almost anything that comes before them, not refusing an occasional young bird, a mouse, or a beetle."^[63] As is generally known, the usual food of these animals is of a vegetable nature. "Reindeer devour hundreds and thousands of Lemmings."^[64] Mr. J.A. Thomson states that he had a report on creditable authority that in the hard winter 1894-95, Stags in Aberdeenshire were known to have eaten Rabbits."^[65] The Chacma Baboon in some parts of the Cape Colony "has largely taken to killing Lambs for the purpose chiefly of sucking the milk with which they have filled their stomachs."^[66] In Egypt, Hyænas are "said to feed on Indian corn, and be destructive to the crops."^[67] In the Scottish Highlands, near the head of Loch Garry, Foxes were strictly preserved and plentiful. A year or two ago, when their cubs were ravenous, these Foxes took to killing Lambs in the fields around, and the unusual spectacle in Britain "was seen of large fires kept burning all night to scare them away, while slumber was driven away from the eyelids of those who lived near by the incessant blowing of tin trumpets and firing of guns charged with powder only."^[68]

Birds.—Ostriches, according to Mr. Cronwright Schreiner, have been known to swallow oranges, peaches, small Tortoises, Fowl and Turkey chickens, and kittens.^[69] The Spreo (Spreo bicolor) "was formerly never known to touch fruit, its food consisting entirely of insects; but during recent years it has, at all events on some farms with which I am acquainted, become very destructive to fruit."^[70] Dr. A.G. Butler, who has much experience in aviculture, states that he has "seen the American Bluebird, the English Starling, the Robin, Redstart, and many other insectivorous birds swallow quantities of seed, and benefit greatly in consequence."^[71] "It is within the memory of some still living that the Rooks first commenced to eat turnips about fifty years ago."^[72] Perhaps the most remarkable case is found in the New Zealand Kea or Parrot (Nestor notabilis), which has recently developed a taste for a carnivorous diet. As described by Mr. Wallace: "It began by picking the sheep-skins hung out to dry or the meat in process of being cured. About 1868 it was first observed to attack living sheep, which had frequently been found with raw and bleeding wounds on their backs. Since then it is stated that the bird actually burrows into the living Sheep, eating its way down to the kidneys, which form its special delicacy."^[73] The absolute accuracy of this explanation of the bird's intentions, has been denied by Messrs. Taylor White and Huddelston, both New Zealand authorities. According to these writers, "the bird settles on the sheep above the kidneys because it is the broadest part, and it can there obtain the best grip of the wool; and Mr. White considers that blood rather than flesh is what the bird desires.^[74] On the island of Porto Santo, near Madeira, the stomach of a Kestrel was found to contain "nothing but seven Snail shells (Helix pisana), which had been swallowed whole."^[75] As Darwin enquires, "Can a more striking instance of adaptation be given than that of a Woodpecker for climbing trees and seizing insects in the chinks of the bark? Yet in North America there are Woodpeckers which feed largely on fruit, and others with elongated wings which chase insects on the wing."^[76] The Great Titmouse (Parus major), by its larger size and stronger bill, is adapted to feed on larger insects, and is even said sometimes to kill small and weak birds. The smaller and weaker Coal Titmouse (Parus ater) has adopted a more vegetarian diet, eating seeds as well as insects, and feeding on the ground as well as among trees.^[77] It has been stated that "on Cocos Islands, when the Boobies are not nesting and have consequently left, the Frigate birds (Tachypetes aquila) are unable to procure their ordinary food, which consists of fish taken from the Boobies, and that they then swallow seeds of Guilandina and beans, which they find floating in the sea, and on flying to the land vomit them up again, apparently merely using them to fill up temporarily the empty crops."^[78] Mr. Watson, in describing the effects of illegitimate fishing in our own country, writes, "In one outlying village during last close season poached Salmon was so common that the cottagers fed their poultry upon it right through the winter."^[79] "After Hunter had fed a Sea Gull on grain for a year, he found that the inner coat of its stomach had grown hard, and its muscles had thickened, thus forming a true gizzard, although the Sea Gull normally has a soft stomach, as it lives upon the soft flesh of fishes."^[80]

Dr. Vosseler, in making some experiments on young Salamanders (Salamandra maculata), inadvertently left some in an aquarium for over a year unfed. "Investigations showed that these creatures, which usually fed on worms, all kinds of larvæ, &c, had nourished themselves with Algæ together with Infusoria. They had thus become almost complete vegetarians."^[81]

Insects.—Numerous instances will occur to most entomologists, and are to be found scattered in entomological literature. We will again quote from other writers: "Many caterpillars, though plants are their proper food, will occasionally exhibit depravity of taste, and if kept with their own kind or with the larvæ of other moths, may turn cannibal, and make away with the company. Similarly the large green Grasshopper will eat insects smaller than itself, as well as its ordinary vegetable diet."^[82] The household beetle pest Dermestes, whose larvæ not only prey on flitches of bacon, meat in larders, bladders covering jam-pots, and even books and papers, "have sometimes actually imitated the example of Anobium, and bored into wood, feeding on the timber as they advanced."^[83] In various places, such as parts of India, for example, Mosquitos are found in swarms in spots never visited by human beings, and in which there are no large mammals. It has been suggested that, failing to obtain blood, Mosquitos support themselves on the juices of plants, but no observations in support of this have been recorded.^[84] Even the sexes in some insects are totally diverse in the nature of their food. In the Diptera, of the families Culicidæ and Tabanidæ, according to Prof. Westwood, "it is only the females of these insects which are blood-suckers, the males being found on flowers; and Meigen discovered that the mouth of the latter sex is destitute of mandibles."^[85]

Mankind.—Even man can acquire a partiality for salt or brackish water. Barrow relates that an old man in the Bokkeveld of South Africa, "who from his infancy till a few years past had lived in Zwartland, never missed an opportunity of sending thither a few bottles to be filled with the briny water for his own particular use; the pure stream of the mountain, as he asserted, not being able to quench his thirst."^[86] The South Australians first learnt from Europeans to eat Oysters.^[87] The Australians do not, however, eat everything indiscriminately, but reject several things eaten by Europeans, as certain fish, crustaceans, or fungi; yet they feel no disgust at such things as maggots or rotten eggs, or even the contents of the intestines of animals taken in hunting.^[88]

Plants can also vary the nutrient salts they absorb according to the supply of the same. In the yew (Taxus baccata) there is frequently a replacement of calcium by magnesium. On comparing the quantities of calcium and magnesium in the ash of yews grown on lime and on gneiss, respectively, with those yielded in the case of serpentine formation, we find that magnesia preponderates considerably in weight over lime in a yew from serpentine rocks (which are in the main a compound of magnesia and silicic acid), whilst the proportion between these two salts is reversed in a yew grown upon limestone. The obvious inference from the table is that, in plants from a serpentine ground, lime is to a great extent replaced by magnesia.^[89]

Among other vagaries in animal diet may be mentioned that of Snails, who also devour insects, particularly Coleoptera.^[90] On the other hand, the operation is sometimes reversed. M. Flaminio Baudi found Cychrus cyclindricollis feeding on the body of Helix frigida;^[91] and Mr. Trovey Blackmore had observed Carabus stenocephalus to feed on the abundant Snails in Morocco.

Such facts as these tend to prove that a fauna is not happy by having no history, as is so often and so easily imagined; but rather that its history is like that of a continental humanity—one series of wars, attack not on all sides at once, but ever recurring from one quarter or another. The friend of to-day may have been the enemy of a long ago. Environmental changes may have produced, by a scarcity of usual food, a change of diet, and then a race of animals hitherto enjoying a comparative immunity from attack may suddenly become almost annihilated by unexpected foes. Thus we may now find an inherited mimetic resemblance among insects and other living creatures which we seek in vain to explain by observed attack, and consequently cannot prove the present need of protection. These disguises are often like remains of old earthworks which we find on our peaceful downs; reminiscences of past struggles, records that such did once exist. And thus the suggestion is forced upon us that much present mimicry in nature is obsolete, more to be studied and explained by a zoological archæologist than by an outdoor observer, and accounts for the frequent remarks made from time to time to the writer by candid and competent naturalists abroad, that so much convincing theory at home receives little support when nature is cross-examined in her tropical and sub-tropical fastnesses.

 

In a book written by a popular writer, the late Prof. Henry Drummond, and which must have been read largely by the general public, for before us is the fourth edition of 'Tropical Africa,' which is described as "completing twenty-fifth thousand," there is a chapter devoted to "Mimicry; the ways of African insects."^[92] "Protective resemblance" would perhaps have been a more applicable title to the phenomena considered than "mimicry,"^[93] which the author defines as "imposture in nature." But the peculiarity in this chapter is that the author, after agreeing in the fullest manner with the usual conception of the term "mimicry," as held by most biologists, and stating that "mimicry depends on resemblances between an animal and some other object in its environment of which it is a practical gain to the creature to be a more or less accurate copy,"^[94] appears to altogether explain away that conclusion by the subsequent remark that, "while in some animals the disguises tend to become more and more perfect, the faculties for penetrating them in other animals must continually increase in subtlety and power."^[95] This argument, if it could be substantiated, appears to be, and has always impressed the writer, as one of the most complete answers to the whole theory of the protective meaning of these disguises. For if by the slow process of adaptation all variations tending to these disguises were increased and perpetuated by the process we express as "natural selection," thus ever helping the "survival of the fittest," and at the same time these changes or developments were equally studied and more keenly detected by the attentive and hungry host of insect enemies, the relations between the attackers and the attacked, the eaters and the eaten, would remain much the same at the commencement and end of the process. And therefore what becomes of Prof. Drummond's conception of mimicry, with its "practical gain," if the enemies sought, or supposed to be deceived thereby have their penetrating faculties continually increasing in subtlety and power? A moth, Agrotis cursoria, not uncommon to the sand-hills on the coast of our own country, "hides in the daytime in dense tufts of Ammophila arundinacea (Marram grass) close to the surface of the sand, and among other plants on the sea sand-hills." But "its partiality for this shelter is apparently well known to the birds, as is testified by the numbers of detached wings to be seen lying about."^[96] Mr. Rodway gives a similar experience in the Guiana Forest:—"Invisibility is a striking characteristic of every living thing in the forest. At first a stranger observes nothing but a scene of desolate confusion. Later, however, he begins to distinguish one tree from another, and learns where to look for a particular animal. Then he wonders how he could have missed the signs which now impress themselves upon his eyes."^[97] It is similar to the extra thickness in the armour of the ironclad, which is always influencing the construction of guns possessing greater penetrating power. It is like the acquired aptitude of the village bird-nesting boy, who with difficulty succeeds in making the town lad see the concealed nest he is about to take; or the experienced eye of the angler which recognizes the Trout, undetected by the ordinary walker on the bank. Or again, watch the rambles of the out-door collector and the closet-naturalist; or the entomologist who discovers and captures, and the other entomologist who only classifies and describes. It is the old remark of "Eyes" and "No Eyes."^[98] If then we can for the purpose of sport or science pit our discerning faculties against the extreme power of animal disguises,^[99] how much more must that detective discrimination have been acquired by those creatures whose very lives are so largely passed in the search, and depend on the capture of these mimicking fugitives. Even the obscure Coccids are preyed upon by birds. Mr. Newstead found specimens in the stomach of the Blue Tit (Parus cæruleus), and remarks:—"These birds must have keen eyes to distinguish this species, for it is well protected both in colour and texture. The central red-brown speck in the scale is the only indication of its presence, and altogether it may be considered the best protected of any of our British Coccidæ."^[100] Again, birds learn to recognise hurtful as well as advantageous objects as exemplified by telegraph wires. When these were first elevated they caused great mortality among birds which flew against them, but after a time the wires were avoided, and that loss in avian life was vastly reduced. Birds certainly acquire experience and avoid dangerous food. Frank Buckland relates that a keeper at Castle Forbes poisoned dead Rabbits, and "picked up as many as twenty-one Magpies and Crows to one Rabbit at one time." But "the cunning birds found out that it was dangerous to peck at dead Rabbits, in vain therefore were they laid down; the Crows and Magpies were for a season triumphant. But the keeper substituted Wood Pigeons for Rabbits, and the 'vermin birds' once more fell victims."^[101] It is not related how long this bait sufficed. Eimer relates that, requiring Sparrows for the zootomical studies of his students, he procured a new and ingeniously constructed trap. "The result of the use of my trap was surprising; almost immediately quite a dozen Sparrows were caught in it. These were brought away as carefully as possible, so that none were taken out in sight of their companions. The trap was again set, and this time nine Sparrows were caught equally quickly. I was very pleased with the invention, for it seemed likely to put an end for the future to all my difficulties. But it was to be otherwise. I noticed already that all the Sparrows caught were young birds, hatched the same spring, and therefore of little experience. Not a single old Sparrow had entered the trap. And when I set it for the third time, not one Sparrow went into it—it stood for week after week; the yard was full of Sparrows, but I caught no more. However, I looked forward confidently to the next year—then I thought, young Sparrows will get caught again; and about two dozen would have been enough material for my purpose. But I had reckoned without the intelligence of the Sparrows. When I got out the trap again next year, and had it set, not a Sparrow went into it. But a curious spectacle was observed: apparently several Sparrows had the desire and the intention to go into the trap, and these were obviously the young inexperienced birds which had been hatched since the trap was last set; but others, of course the older birds who had learnt the danger of the wire-basket from the loss of their families, kept them back by constant earnest warnings, for the males, as soon as one of the yellow beaks approached the cage, uttered their warning cry most loudly, the cry which they always make when danger is present, and which consists in a long shrill rattling 'r-r-r-r-r.'"^[102] It is well known to poachers that when once a Hare has been netted, there is no chance of its being taken again in like manner. Rather than go through a second time, even though a "lurcher" be but a yard behind, it will either "buck" the gate, or take the fence.^[103] Grazing cattle will not touch plants that would be deadly or hurtful to them; but if taken to a distant land, to another continent where unknown herbs grow they are unable to distinguish, they sicken or die of the poison they have eaten.^[104]

But perhaps it is only by recognizing the full force of the objections that we can hope to fairly realize the strength of the theory thus called in question. If these mimicking or protective disguises have not been incidental to a phase of evolution, they must have been created as they are, and even the advocates of this view—if any competent are left—would surely not enunciate the idea of a purposeless creation, or the fanciful freaks of a Demiurgos, for such must be the case if no purpose is served by these extraordinary imitations. On the other hand, what can the evolutionist reply when he is confronted with the only other postulate of astonished ignorance expressed in the terms of "a freak of nature"?^[105]

The solution of the difficulty may—we repeat—probably be found in ceasing altogether to explain some biological features of the past by causes operating in the present, and perhaps only in the present epoch. In fact, many animals affording undoubted instances of protective resemblance and mimicry now show in the observed dangers of their lives, so little raison d'être for these wonderfully evolved assimilations in colour and structure, that it seems more philosophical to conceive them as survivals of a past when there was a greater danger and a larger need.

(To be continued.)

 

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1. In the years to come, when we shall be estimated only as advanced teleologists, science may probably have solved the problem of animal colouration. When that is effected, who dare say that the inductive process will be unable to exhibit the long past in varied and tinted landscape on the walls of the museum, where now osteology only holds her cold and partial sway?
2. Mr. Sedgwick is of opinion that there is much to be said for the view that the greater part of evolutionary change had already taken place in pre-Cambrian times before the fossiliferous period. "If this view was correct—and the probability of it should be borne in mind—the main part of the evolution of organisms must have taken place under totally different conditions to those now existing, and must remain for ever unknown to us." (Proc. Fourth Internat. Congr. Zoology, Cambridge, 1898, p. 75.)
3. 'Darwinism,' p. 202.—Mr. Skertchley distinguishes "protective resemblance" as copying stationary objects, and "mimicry" as simulating moving ones (Ann. & Mag. Nat. Hist. ser. vi. vol. iii. p. 478).
4. Some Phasmas vary in colour in the same species, as noticed in Mauritius. Cuvier was not unobservant of these peculiarities, as, referring to the Phasma rossia, from the South of France, he describes it as either of a yellow-green or greyish brown. (Quoted by Nicholas Pike, 'Sub-Tropical Rambles,' p. 164.) It is interesting to note a superficial parallelism in structure in the Skeleton-Shrimps (Caprellidæ) with the Phasmidæ, and in Mantis-Shrimps (Stomatopoda) with the Mantidæ, of which a good example may be found in the Squilla mantis, Rondel.
5. 'Contributions to the Theory of Natural Selection,' p. 64.
6. 'Tropical Africa,' 4th edit. p. 173.
7. 'Tropical Nature,' p. 93.—In North America "Walking-sticks (Diapheromera) are eaten by the Crow-Blackbird and two species of Cuckoos."—S. D. Judd (American 'Naturalist,' vol. xxxiii. p. 462).
8. "Descriptions of Fifty-two New Species of Phasmidæ" (Trans. Linn. Soc. vol. xxv. p. 323).
9. 'Origin of Species,' 6th ed. p. 182.
10. Zoologist,' 3rd ser. vol. xviii. pp. 291-2.
11. Heilprin, 'Geograph. and Geol. Distr. of Animals,' p. 150.—Pharnacia serratipes, from Borneo, the largest known species, is stated by Mr. Kirby to measure nearly thirteen inches from the front of the head to the extremity of the abdomen (Trans. Linn. Soc. vol. vi. (2nd ser.) p. 448).
12. 'Cambridge Nat. Hist.' vol. v. p. 276.
13. In 'Zool. Results of Arthur Willey Exped.' pt. i. p. 78.
14. 'Evolution and Taxonomy.'—'The Wilder Quarter-Century Book,' p. 56.
15. 'Collected Essays,' vol. viii. p. 297.
16. 'Bull. U.S. Geol. Surv.' No. 124, pp. 30-1 (1895).
17. 'History of Creation,' 4th ed. vol. ii. p. 123.
18. 'Text-Book of Geology,' pp. 724-5.
19. Scudder, "Syst. Rev. Pres. Knowl. Foss. Ins." (Bull. U.S. Geol. Surv. No. 31, p. 49 (1886)).
20. This seems to be the current statement based on present knowledge; but, as Huxley has observed, analogy seems to be rather in favour of, than against, the supposition that Amphibia and Reptilia, or even higher forms, may have existed, though we have not yet found them in the Devonian epoch ('Collected Essays,' vol. viii. p. 385).
21. The oldest known bird—Archæopteryx—comes from the Solenhofen Limestone in the Upper Jurassic series—a rock which has been especially prolific in the fauna of the Jurassic period (A. Geikie, 'Text-Book of Geology,' 2nd edit. p. 783).
22. O.C. Marsh, 'Sixteenth Ann. Rept. U.S. Geol. Survey,' p. 147 (1896).
23. 'Collected Essays,' vol. iv. p. 85.
24. 'Collected Essays,' vol. ii. p. 354.
25. 'The Study of Animal Life,' 2nd edit. p. 258.
26. 'Roy. Nat. Hist.' vol. v. p. 8.
27. 'Hist. of British Fossil Mammals,' p. xxv.
28. 'Geographical Journal,' vol. vii. p. 295.
29. These birds were, however, probably most divergent from present avian types. Such an example is the Archæopteryx of the Jurassic or Oolitic epoch, which was not only furnished with teeth, but had a long tapering tail, with other indications of reptilian affinity.
30. T.G.B., reviewing in 'Nature' (vol. xlix. p. 196), 'Some salient Points in the Science of the Earth,' by Sir J.W. Dawson, speaks of the larger reptiles crawling over the soft mud, and leaving tracks in the coal-fields of Nova Scotia, and remarks: "These discoveries came as a complete surprise to the scientific world in days when few or no reptiles were known of earlier date than the Permian."
31. 'Nat. Condit. of Existence as they affect Animal Life,' p. 126.
32. Prof. Semper's definition of the "optimum temperature" seems to be contained in the following sentence:—"The interval between the daily extremes may be great or small without any alteration in the daily meteorological mean; moreover, the favourable temperature—the optimum of temperature for the animal—may either coincide with the meteorological mean, or lie nearer to one of the extremes—the maximum or minimum—than the other."
33. 'Catalogue of Orthoptera in the Brit. Museum's Coll.' Pt. i. Phasmidæ (1859).
34. "Descriptions of Fifty-two New Species of Phasmidæ" (Trans. Linn. Soc. vol. xxv. p. 323).
35. Our knowledge of pre-Carboniferous insects is limited, but present knowledge goes to prove that a considerable insect-fauna existed in more ancient times. Thus, as Mr. Comstock has observed:—"Of Devonian insects we know several.... These differ among themselves to such an extent that we are forced to conclude, without taking into account the two known Silurian insects, that already at that early time there was a large and varied insect-fauna, of which the more primitive forms have not been discovered" ('Evolution and Taxonomy—The Wilder Quarter-Century Book,' p. 55).
36. S.H. Scudder, 'Bull. U.S. Geol. Surv.' No. 124, p. 30 (1895).
37. Louis Robinson, 'Wild Traits in Tame Animals,' p, 150.
38. 'Life, Letters, and Journals of Chas. Lyell,' vol. i. p. 468.
39. "In the earlier periods of the earth's history, reptiles were no doubt the principal enemies with which butterflies had to deal" (Beddard, 'Animal Coloration,' 2nd edit., p. 211).
40. 'Cassell's Nat. History,' vol. iv. pp. 379-80.
41. Among the slow Lemurs or Galagos we find enemies of the Phasmidæ. Mr. Lydekker, though not giving his authority, writes: "Some of the smaller species will readily devour Locusts, and the peculiar leaf-like Mantides, or praying insects" ('Royal Nat. Hist.,' vol. i. p. 223); but as no fossil lemuroid forms are at present known anterior to tertiary times, these records do not affect our enquiry.
42. "The First Voyage round the World by Magellan" (Hakluyt Society).
43. Preface to the 'Museum Regis Adolphi Friderici,' transl. by Jas. Ewd. Smith (1798).
44. 'The Naturalist in Nicaragua,' p. 19.
45. L.F. de Pauw, 'Bull. Soc. Anthrop. Bruxelles,' 1894, p. 140.
46. 'Across Thibet,' vol. ii. p. 64.
47. 'Eight Months in an Ox Waggon,' p. 174.
48. J. Barrow, 'Travels in the Interior of Southern Africa,' vol. i. p. 53.
49. 'Badminton Magazine,' vol. ii. pp. 840-1.
50. Guillemard, 'Cruise of the Marchesa,' 2nd edit. p. 68.
51. Ibid. p. 76.
52. Ibid. p. 88.
53. 'Nat. Hist. Selborne,' Harting's edition, p. 96.
54. Ibid. p. 97, note.
55. 'The Naturalist in La Plata,' pp. 60 and 71.
56. C. J. Cornish, 'Animals of To-day,' p. 235. For other instances of changed diet, cf. ibid. p. 185.
57. 'Royal Nat. Hist.,' vol. ii. p. 93.
58. 'American Naturalist,' Sept. 1884.
59. 'Origin of Species,' 6th edit. p. 138.
60. Lydekker, 'Roy. Nat. Hist.,' vol. ii. p. 411.
61. "In California it has forgotten how to burrow" (C.J. Cornish, 'Wild England of To-day,' p. 189).
62. Writer in the 'Times'; quoted in 'Spectator,' January 4th, 1896.
63. Lydekker, loc. cit. vol. iii. p. 125.
64. Brehm, 'From North Pole to Equator,' p. 75.
65. Ibid, editor, note, p. 567.
66. S. Schonland, 'Zoologist,' 4th ser. vol. i. p. 155.
67. A. Leith Adams, 'Naturalist in Nile Valley and Malta,' p. 47.
68. Rev. M.G. Watkins, 'Longman's Magazine,' February, 1886.
69. 'Zoologist,' 4th ser. vol. i. p. 106.
70. S. Schonland, loc. cit. vol. i. p. 155.
71. Loc. cit. vol. i. p. 253.
72. Wm. Wilson, Jun., 'Investigations into Applied Nature,' p. 44.
73. 'Darwinism,' p. 75.
74. 'Zoologist,' 3rd ser. vol. xix. p. 293; also cf. Godfrey ('Zoologist,' 1898, pp. 216–17). Another New Zealand Parrot (Strigops habrobtilus) has lost its power of flight, and lives in burrows or other natural cavities when not abroad.
75. Hon. Cecil Baring and W.R. Ogilvie Grant ('Zoologist,' 3rd ser. vol. xix. p. 403).
76. 'Origin of Species,' 6th edit. p. 141.
77. A.R. Wallace, 'Darwinism,' p. 108.
78. G. Clunies Ross, 'Natural Science,' vol. viii. p. 190.
79. 'Sketches of British Sporting Fishes,' p. 127.
80. Cf. Brooks, 'The Foundations of Zoology,' p. 57.
81. Eimer, 'Organic Evolution,' Eng. transl., p. 108.
82. Badenoch, 'Romance of the Insect World,' p. 45.
83. A.E. Butler, 'Our Household Insects,' p. 25.
84. R.J. Pocock, 'Roy. Nat. Hist.,' vol. vi. p. 52.
85. 'Modern Classification of Insects,' vol. ii. p. 541.
86. 'Travels in the Interior of Southern Africa,' vol. i. p. 360.
87. Ratzel, 'History of Mankind,' vol. i. p. 337.
88. Ibid. p. 361.
89. Kerner and Oliver, 'Nat. Hist, of Plants,' vol. i. p. 70.
90. Cf. Wollaston and other observers, 'Zoologist,' vol. i. p. 201; vol. iii. pp. 943, 1035, 1038.
91. 'Petites Nouvelles Entomologiques.'
92. Gordon Cumming as early as 1850 drew attention to "mimicry" or "protective resemblance" among insects. He did not use the terms, but clearly described the facts. 'Five Years' Hunting Adventures in South Africa' (Compl. Pop. Edit.), p. 132.
93. This word is now becoming not uncommon in general literature, and its original meaning—at least as used in biology—will tend to become obscured. Thus Max Nordau writes of "the religious mimicry of the French bourgeoisie, which was to make them resemble the old nobility" ('Degeneration,' p. 113).
94. 'Tropical Africa,' 4th edit. p. 162.
95. 'Tropical Africa,' 4th edit. p. 180. A similar opinion was expressed by the late Fras. Pascoe: "It is not likely that animals whose lives depend on their sight should be easily deceived; though with our mostly unobservant eyes a green caterpillar on a green leaf may easily escape notice" ('A Summary of the Darwinian Theory of the Origin of Species,' p. 13).
96. C.G. Barrett, 'The Lepidoptera of the British Islands,' vol. iii. p. 330.
97. 'In the Guiana Forest,' p. 48.
98. Tennyson was an acute observer of nature. He once asked Miss Thackeray to notice whether the Sky-Lark did not come down sideways on the wing. (W.J. Dawson, 'The Makers of Modern English,' 3rd edit. p. 182.)
99. My friend Dr. Percy Rendall, then at Barberton in the Transvaal, a most enthusiastic and successful collector, in reply to my expressed wish that he would still keep a sharp look-out for Phasmidæ, replied: "I am keenly on the look-out for them, and will in most cases back my eyes against almost any kind of insect protective resemblance dodges."
100. 'Entomol. Month. Mag.,' ser. 2, vol. vi. p. 85.
101. 'Curiosities of Nat. Hist.,' pop. edit., 2nd ser. pp. 97–8.
102. Eimer, 'Organic Evolution,' Eng. Transl., pp. 235–6.
103. John Watson, 'Poachers and Poaching,' p. 270. "A new trap catches more than a better old one until the animals have learned to understand it, and young animals are trapped more easily than old" (Prof. Tyler, 'The Whence and the Whither of Man,' p. 119).
104. Heyn and Stallybrass, 'The Wanderings of Plants and Animals,' p. 402.
105. How different are the theological or teleological views of the Middle Ages to the scientific conception of the struggle for existence as held to-day. We can no longer apostrophize the order Aves in the delightful utterances of the good and saintly Francis of Assisi:—"Brother birds, you ought to praise and love your Creator very much. He has given you feathers for clothing, wings for flying, and all that is needful for you. He has made you the noblest of His creatures; He permits you to live in the pure air; you have neither to sow nor to reap, and yet He takes care of you, watches over you and guides you" ('Life of St. Francis of Assisi,' by Paul Sabatier, Eng Transl., pp. 176–7). Rather now we see

     ⁠"The grub eats up the pine,
     ⁠The finch the grub, the hawk the silly finch."