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(716) 288 - 5969 - Fo» JSA ^ EDITED BY PKOEESiyQR KNIGHT THE STUDY OF ANIMAL LIFE The Study of Animal Life BY J. ARTHUR THOMSON, M.A, F.R.S.E. LECTURER ON ZOOLOGY, SCHOOL OF MEDICINE, EDINBURGH JOINT-AUTHOR OF 'THE EVOLUTION OF SEX ' AUTHOR OK 'outlines OF ZOOLOGY ' THIRD EDITION WITH JLLUSTNAT/OXS TORONTO G. N. MORANG & COMPANY LIMITED LONDON JOHN MURRAY 1902 0L4 i^'^ " Rut. for my part, wluch write the English story. 1 acknowledge that no man must looke for that at my hands, which I have not received from some other : .or I would bee unwilling to.write anythmg untrue, or uncertaine out of mine own invention ; and truth on every part is so deare unto me. that 1 will not lie to bring any man m love and admiration with God and his works, for God needeth not the hes "^ "'^'^- TOPSELL'S Apologia (1607). J^ %' -^ ^ 5 PREFACE This book is intended to help those who would study animal life. From different points of view I have made a series of sketches. I hope that when these are united in the mind of the reader, the picture will have some truth and beauty. My chief desire has been to give the student some impulse to joyousncss of observation and freedom of judgment, rather than to satisfy that thirst for knowledge which leads many to intellectual r'nsobriety. In pursu- ance of one of the aims of this series, I have also tried to show how our knowledge of animal life has grown, and how much room there is for it still to grow. A glance at the table of contents will show the plan of the book ; first, the everyday life of animals, next, their internal activities, thirdly, their forms and structure, and finally, the theory of animal life. This is a commonly accepted mode of treatment, and it is one by which it is possible in different parts of the book to appeal to students of different tastes. For, in lecturing to those who attend University Extension Courses, I find that seniors are most interested in the general problems of evolution, heredity, and environment ; that others care more about the actual forms of life and their structure; that many desire to have a clear understanding of the functions of the animal body ; while most wish to study the ways of living animals, their struggles and loves, their homes and 15914 v! Preface societies. To each of these class s of students a quarter of this volume is dedicated ; perhaps they will correct their partiality by reading the whole. As to the two Appendixes, I may explain that instead of giving references at the end of each chapter, I have combined these in a connected bibliut^aphy ; the other Appendix on " Animal Life and Ours " may show how my subject is related to some of the others usually discussed in University Extension Courses. My friend Mr. Norman Wyld has written the three chapter, c. " The Powers of Life," pp. 1 2 5-1 66, and I am also inu-^' jd to him for helpful suggestions in regard to other parts of the book. I have to thank Mr. Murray, Messrs. Chambers, and Mr. Walter Scott, for many of the illustrations; while several original drawings have been made for me by my friend Mr. William Smith. Professor Knight and Mr. John Murray have given me many useful hints while the book was passing through the press, and Mr. Ricardo Stephens was good enough to read the proof sheets. J. A. T. School of Medicine, Edinburgh, May 1893 CONTENTS PART I The Everyday Life of Animals CHAPTER I THE WEALTH OF LIFE f Variety of life— ^. Haunts of life— :^. Wealth of form— ^ Wealth of numbers— $. Wealth of beauty . . . Pages 1-17 CHAPTER II THE WEB OF LIFE I. Dependence upon surroundings -^a. /nter- relations ' 184-203 CHAPTER XIII THE PAST HISTORY OF ANIMALS I. The two records — 2. Imperfection of the geological record 3. Palaontological series—^ Extinction of types — 5. Various diffi- culties — 6. Relative antiquity of animals , . 204-209 CHAPTER XIV THE SIMPLEST ANIMALS The simplest forms of life— Q^. Surv^ of Protoaoa—^. The common Amcaa—^. Structure of the Prototoa—i. Life cf Prototoa-d, Psychical life of the Prototoa— J. History of the ProtoMoa—i. Rela- lion to the earth— ^. Relation to other forms (f life— 10, Relation t«man ...... 2io-a2X XI PART IV Contents CHAPTER XV BACKBONELESS ANIMALS T. Sponges — 3. Stinging - animals or Cailenteraia—^. "Worms" — 4. £cAinoderms—s. Arthropods — 6. Molluscs . Pages 932-347 CHAPTER XVI BACKBONED ANIMALS I. Balanoglossus—3. Tunicates—^. The LnnctUt—4. Round-mouths or Cyclostomata — s. Fishes — 6. Amphibians — 7. Reptiles— 9. Birds— g. Mammals ..... 248-272 PART IV The Evolution of Animal Life CHAPTER XVII THE EVIDENCES OF EVOLUTION I. The idea of evolutior—a. Arguments for evolution : Physiological, Morphological, Historical— -i. Origin of life . . 273-281 CHAPTER XVIII THE EVOLUTION OF EVOLUTION THEORIES 1. Greek philosophers— 3. AristotU—^. Lucretius— 4. Evolutionists before Darwin-i. Three old masters : Bujfbn, Erasmus Darwin, Lamarck— 6. Darwin— 7. Darwin's fellow -workers— i. The present state of opinion .... 282.302 CHAPTER XIX THE INFLUENCE OF HABITS AND SURROUNDINGS I. The influence of funcHon—a. The influence of surroundings— 2. Our own environment . .... 303.319 xii Contents TAKT IV CHAPTER XX HEREDITY X. The facts tf heredity— i. Theories of heredity, historical retrospect— 3. The modem theory of heredity— /^. The inheritance cf acquired characters— $. Social and ethical aspects— 6. Social inheritance Pages 330-339 APPENDIX I ANIMAL LIFE AND OURS A. Our relation to animals : 1. Affinities and differences between man and monkeys— t. Descent cf man — 3. Various opinions about the descent of man— /^. Ancestors of man—S- Possible factors in the ascent of man. B. Our relation to Biology : 6. The utility of science— 7. Practical justification of biology ~-Z. Intellectual justification of biology ..... 340-35° APPENDIX II SOME OF THE BEST BOOKS ON ANIMAL LIFE A. Books on " Zoology "^ti. Books on "Natural History" —C. Books or "Biology" ..... 3S1-369 Index 37I-37S PART I THE EVERYDAY LIFE OF ANIMALS CHAPTER I THE WEALTH OF LIFE I. Variety of Life— 2. Haunts of Life~i. Wealth of f-^m— 4. Wealth of Numbers— s^. Wealth of Beaut;, The first steps towards an appreciation of animal life must be taken by the student himself, for no book-lore can take the place of actual observation. The student must wash the quartz and dig for the diamonds, though a book may help him to find these, and thereafter to fashion them into a treasure. Happily, however, the raw material of observation is not rare like gold or diamonds, but near to us as sunshine and rain-drops. Within a few hours' walk of even the largest of our towns the country is open and the animals are at home. Though we may not be able to see "the buzzard homing herself in the sky, the snake sliding through creepers and logs, the elk taking to the inner passes of the woods, or the razor-billed auk sailing far north to Labrador," we can watch our own delightful birds building their "homes without hands," we can study the frogs from the time that they trumpet in the early spring till they or their offspring seek winter quarters in the mud, we can follow the bees and detect their adroit burglary of the B I ! i ' i : I 11 ! ii: ! 3 TAe Study of Animal Life part i flowers. And if we are discontented with our opportunities, let us read Gilbert White's History of Selborne^ or how Darwin watched earthworms for half a lifetime, or how Richard Jefferies saw in the fields and hedgerows of Wilt- shire a vision of nature, which seemed every year to grow richer in beauty and marvel. It is thus that the study of Natural History should begin, as it does naturally begin in childhood, and as it began long before there was any exact Zoology, — with the observation of animal life in its familiar forms. The country schoolboy, who watches the squirrels hide the beech nuts and pokes the hedgehog into a living ball, who finds the nest of the lapwings, though they decoy him away with prayerful cries, who catches the speckled trout in spite of all their caution, and laughs at the ants as they expend hours of labour on booty not worth the having, is laying the foundation of a naturalist's education, which, though he may never build upon it, is certainly the surest. For it is in such studies that we get close to life, that we may come to know nature as a friend, that we may even hear the solemn beating of her heart. The same truth has been vividly expressed by one whose own life-work shows that thoroughness as a zoologist is consistent with enthusiasm for open-air natural history. Of the country lad Dr. C. T. Hudson says, in a Presi- dential Address to the Royal Microscopical Society, that he " wanders among fields and hedges, by moor and river, sea- washed cliff and shore, learning zoology as he learnt his native tongue, not in paradigms and rules, but from Mother Nature's own lips. He knows the birds by their flight and (still rarer accomplishment) by their cries. He has never heard of (Edicnemus crepitans, the Charadrius pluvialis, or the Squatarola cinerea, but he can find a plover's nest, and has seen the young brown peewits peering at him from behind their protecting clods. F -. has watched the cun- ning flycatcher leaving her obvious and yet invisible young in a hole in an old wall, while she carries off the pellets that might betray their presence ; and has stood so still to see the male redstart that a field-mouse has curled itself on his warm foot and gone to sleep." til i ! I i ! t^jviSWiStX,^-. - CHAP. I The Wealth of Life But the student must also attempt more careful studies of living animals, for it is easy to remain satisfied with vague "general impressions." He should make for himself — to be corrected afterwards by the labours of others — a "Fauna" and "Flora" of the district, or a "Naturalist's Year Book " of the flow and ebb of the living tide. He should select some nook or pool for special study, seeking a more and more intimate acquaintance with its tenants, watching them first and using the eyes of other students afterwards. Nor is there any difficulty in keeping at least freshwater aquaria— simply glass globes with pond water and weeds — in which, within small compass, much wealth of life may be observed. Those students are specially fortunate who have within reach such collections as the Zoological Gardens and the British Museum in London ; but this is no reason for failing to appreciate the life of the sea-shore, the moor-^. id, and the woods, or for neglecting to gain the confiden.e of fishermen and gamekeepers, or of any whose knowledge of natural history has been gathered from the experience of their daily life. I. Variety of Life.— Between one form of life and another there often seems nothing in common save that both are alive. Thus life is characteristically asleep in plants, it is generally more or less awake in animals. Yet among the latter, does it not doze in the tortoise, does it not fever in the hot-blooded bird.? Or contrast the phlegmatic am- phibian and the lithe fish, the limpet on the ruck and the energetic squid, the barnacle passively pendent on the float- ing log and the frolicsome shrimp, the cochineal insect like a gall upon the leaf and the busy bee, the sedentaiy corals and the free-swimming jellyfish, the sponge on the rock and the minute Night-Light Infusorians which make the waves sparkle in the summer darkness. No genie of Oriental <"incy was more protean than the reality behind the myth — the activity of life. 2. Haunts of Life.— The variety of haunt and home is not less striking. There is the great and wide sea with swimmmg thmgs innumerable, our modem giants the whales the seals and walruses and the sluggish sea-cows, the flipl i \\ 4 The Study of Animal Life part \ pered penguins and Mother Carey's chickens, the marine turtles and swift poisonous sea-serpents, the true fishes in prolific shoals, the cuttles and other pelagic molluscs; besides hosts of armoured crustaceans, swiftly-gliding worms, fleets of Portuguese Men-of-War and throbbing jelly- fish, and minute forms of life as numerous in the waves as motes in the sunlit air of a dusty town. " But what an endless worke have I in hand, To count the seris abundant progeny, Whose fruitful seede farre passeth those on land, And also those which wonne in th' azure sky ; For much more eath to tell the starres on hy, Albe thty endle e seem in estimation, Then to recount ihe seas posterity ; So fertile be the flouds in generation. So huge their numbers, and so numberlcsse their nation." Realise Walt Whitman's vivid picture : — " The World below the brine. Forests at the bottom of the sea the branches and leaves, Sea-ktUice, vast lii liens, strange tluwers and seeds,— the thick tang'e, the openings, and tlic pink turf. Different colours, pale grey and green, purple, white, and gold— the play of light through the water. Dumb swimmers there among the rocks— coral, gluten, grass, rushes— and the aliment of the swimmers. Sluggish . sistcnccs grazing tlicre, suspended, or slowly crawling close to tlie bottom : The sperm whale nt the surface, blowing air and .piay, or dis- porting with his flukes, Tiie Icaden-eyed shaik, ilie walrus, tie turtle, tlie hairy sea- leopard, and the sting r.iy. I'assions there, wars, pursuits, tribes sight in those ocean depths — breathing that thick breathing air, as so many do." The sea appears to have been the cradle, if not the birthplace, of the earliest forms of animal life, and some have never wandered out of hearing of its lullaby. From the sea, animals sceir to have migrated to the shore and thence to the land, but also to the <,'cat depths. Of the life of the depp sea wc have had certain knowledge only CHAP. I The Wealth of Life I Fi.;. I. -Suggestion of ilccj,-..-.. llf,-. (|„ |,,„t fi.mi .i figure by W. Marshall.) ■.TnK.7?3i«ia^srffi-. rSBK.ra&^trznMHK'.Aut^'B^-iii^BEIRf^ii ::'S1. TAe Study of Animal Life PART I within the last quarter of a century, since the Challenger expedition (1872-76), under Sir Wyville Thomson's leader- ship, following the suggestions gained during the laying of the Atlantic cables and the tentative voyages of the Lightning (1868) and the Porcupine (1870), revealed what was virtually a new world. During 3^ years the Challenger explorers cruised over 68,900 nautical miles, reached with the long ann of the dredge to depths equal to reversed Himalayas, raised sunken treasures of life from over 300 stations, and brought home spoils which for about twenty years have kept the savants of Europe at work, the results of which, under Dr. John Murray's editorship, form a library of about forty huge volumes. The discovery of this ucw world has not on'y yielded rich treasures of knowledge, but has raised a wave of wider than national enthusiasm which has not since died away. We are at present mainly interested in the general picture which the results of these deep -sea explorations present, — of a thickly-peopled region far removed from direct observation, sometimes three to five miles beneath the surface — a world of darkness relieved only by the living lamps of phosphorescence, of silent calm in which animals grow into quaint forms of great unifoimity throughout wide areas, and moreover a cold and plantless world in which the animals have it all their own way, feeding, though apparently without much struggle for existence, on their numerous neighbours, a^d ultimately upon the small organ- isms which in dying sink gently from the surface like snow- flakes through the air. Far otherwise is it on the shore — sunlight and freshening waves, continual changes of time and tide, abundant plants, crowds of animals, and a scrimmage for food. The shore is one of the great battlefields of life on which, through campaign after campaign, animals have sharpened one another's wits. It has been for untold ages a great school. Leaving the sea-shore, the student miglit naturally seek to trace a migration of animals from sea to estuary, ond from the brackish \/ater to river and lake. But this pa^'i, though followed by some animals, does not seem to have i ■'CifA_ \-'<^.i^ mmsmm •yLfrmrssimasaiiaPitrg.^ ,1 c^Mdy •kJ-Te Tliir CHAP. I The [Vealth of Life been that which led to the establishment of the greater part of our freshwater fauna. Professor Sollas has shown with much conclusiveness that the conversion of comparatively shallow continental seas into freshwater lakes has taken place on a large scale several times in the history of the earth. This has been in all likelihood accompanied by the transformation of marine into freshwater species. It is thus, we believe, that our lakes and rivers were first peopled. Many freshwater forms differ from their marine relatives in having suppressed the obviously hazardous free-swimming juvenile stages, in bearing young which are sedentary or in some way saved from being washed away by river currents. Minute and lowly, but marvellously entrancing, are .merous Rotifers, of which we know much through the labours of Hudson and Gosse. These minute forms are among the most abundant tenants of fresh water, and their eggs are carried from one watershed to another on the wings of the wind and on the feet of birds, so that the same kinds may be found in widely separate waters. Let us see them in the halo of Hudson's eulogy : "To ^e into that wonderful world which lies in a drop of water, crossed by some atoms of green weed ; to see transparent living mechanism at work, and to gain some idea of its modes of action ; to watch a tiny speck that can sail through the prick of a needle's point ; to see its crystal armour flashing with ever-varying tints, its head glorious with the halo of its quivering cilia ; to see it gliding through the emerald stems, hunting for its food, i^natching at Us prey, fleeing from its enemy, chasing its mate (th lercest of our passions blazing in an invisib'e speck) ; to see it whirling in a mad dance to the sound of its own music — the music of its happiness, the exquisite happiness of living, — can any one who has once enjoyed th's siglit, ever turn from it to mere books and drawings, without the sense that he has left all fairyland behind him?" Not less lively than the Rotifers are crowds of minute crust.iceans or water-fleas which row swiftly through the clear water, and are eaten in hundreds by the fishes. Hut there are higher forms still : crayfish, and the larvjc of mayflies and dragonflies, mussels ift.vjR:-«p.»« _ jL A .1! ^SJ^- :iKttllWiJ«v-iSiLi *.K? '>3is'-''-fcje»a.'.r!.," s The Study of Animal Life PART I and water-snails, fishes and newts, the dipper and the king- fisher, the otter and the vole. As we review the series of animals from the simplest upwards, we find a gradual increase in the number of those which Hve on land. The lowest animals are mostly aquatic — the sponges and stinging-animals wholly so; worm-like forms which are truly terrestrial are few com- pared with those in water ; the members of the starfish group are wholly marine ; among crustaceans, the wood- lice, the land-crabs, and a few dwellers on the land, are in a small minority ; among centipedes, insects, and spiders the aquatic forms are quite exceptional ; and while the great majority of mollusrs live in water, the terrestrial snails and slugs are legion. In the series of backboned animals, again, the lowest forms are wholly aquatic ; an occasional fish like the climbing- perch is able to live for a tim- ashore ; the mud-fish, which can survive being brought fronj Africa to Europe within its dry " nest " of mud, has learned to breathe in air as well as in water ; the amphibians really mark the transition from water to dry land, and usually rehearse the story in each individual life as they grow from fish-like tadpoles into frog- or newt-like adults. Among reptiles, however, begins that possession of ihe earth, which in mammals is established and secure. As insects among the backboneless, so birds among the backboned, possess the air, achieving in perfection what flying fish, swooping tree- frogs and lizards, and above all the ancient and extinct flying reptiles, have reached towards. Interesting, too, are the exceptions — ostriches and penguins, whales and bats, the various animals which have become burrowers, the dwellers in caves, and the thievish parasites. But it is enough to empnasise ^he fact of a general ascent from sea to shore, from shore to dry land, and eventually into the air, and the fact that the haunts and homes of animals are not less varied than the pitch of their life. 3- Wealth f Form. — As our observations accumjJate, the desire for order asserts itself, and we should at first classify for ourselves, like the savage before us, allowing similar impressions to drav/ together into groups, such as CHAP. I The Wealth of Life birds and beasts, fishes and worms. At first sight the types of architecture seem confusingly numerous, but gradually certain great samenesses are discerned. Thus we distin- guish as higher animals those which have a supporting rod along the back, and a nerve cord lying above this ; while the Imver animals have no such supporting rod, and have their nerve-cord (when present) on the under, not on the upper side of the body. The higher or backboned seiies has its double climax in the Birds and the furred Mammals. Indissolubly linked to the Birds are the Reptiles, — lizards and snakes, tortoises and crocodiles — the survivors of a great series of ancient forms, from among which Birds, and perhaps Mammals also, long ago arose. Simpler in many ways, as in bones and brains, are Amphibians and Fishes in close structural alliance, with the strange double-breathing, gill- and lung-possessing mud-fishes as links between them. Far more old-fashioned than Fishes, though popularly in- cluded along with them, are the Round-mouths— the half- parasitic hag-fish, and the palatable lampreys, with quaint young sometimes called "nine-eyes." Near the ba^e of this series is the lancelet, a small, almost translucent animal living in the sea-sand at considerable depths. It may be regarded as a far-off prophecy of a fish. Ju't at the threshold of the higher school of life, the sea-squirts or Tunicates have for the most part stumbled ; for though the active younj^ forms have been acknowledged for many years as reputable Vertebrates, almost all the adults fall from this estate, and become so degenerate that no zoologist ignorant of their life-history would recognise their true position. Below this come certain claimants for Vertebrate distinction, notably one Balattoglossus, a worm- like animal, idolised by modern zoology as a connecting link between the backboned and backboneless series, and reminding us that exact boundary-lines are very rare in nature. For our present purpose it is immaterial whether this strange animal be a worm -like vertebrate or a vertebrate-like worm. Across the line, among the backboneless animals, it is more difficult to distinguish successive grades of higher xo The Study of Animal Life PART I !l .i i !l and lower, for the various classes have progressed in very different directions. We may liken the series to a school in which graded standards have given place to classes which have " specialised " in diverse studies ; or to a tree whose branches, though originating at different levels, are all strong and perfect. Of the shelled animals or Molluscs there are three great sub -classes, (a) the cuttlefishes and the pearly nautilus, {b) the snails and slugs, both terrestrial and aquatic, and {c) the bivalves, such as cockle and mussel, oyster and clam. Simpler than all these are a few forms which link molluscs to worms. Clad in armour of a very different type from the shells of most Molluscs are the jointed-footed animals or Arthro- pods, including on the one hand the almost exclusively aquatic crustaceans, crabs and lobsters, barnacles and " water-fleas," and on the other hand the almost exclusively aerial or terrestrial spiders and scorpions, insects and centi- pedes, besides quaint allies like the '« king-crab," the last of a strong race. Again a connecting link demands special notice, Peripatus by name, a caterpillar- or worm- like Arthropod, breathing with the air- tubes of an insect or centipede, getting rid of its waste-products with the kidneys of a worm. It seems indeed like «'a surviving descendant of the literal father of flies," and suggests forcibly that insects rose on wings from an ancestry of worms much as birds did from the reptile stock. Very different from all these are the starfishes, brittle- stars, feather-stars, sea-urchins, and sea-cucumbers, animals mostly sluggish and calcareous, deserving their title of thorny-skinned or Echinodermata. Here again, moreover, the sea-cucumbers or Holothurians exhibit features which suggest that this class also originated from among " worms." But " Worms " form a vast heterogeneous «' mob," heart- breaking to those who love order. No zoologist ever speaks of them now as a "class" ; the title includes many classes, bristly sea- worms and the familiar earthworms, smooth suctorial leeches, ribbon-worms or i emerteans, round hair- worms or Nematodes, flat tapeworms and flukes, and many l< CHAP. I The Wealth of Life II others with hardly any characters in common. To us these many kinds of " worms " are full of interest, because in the past they must have been rich in progress, and zoologists find among them the bases of the other great branches — Vertebrates, Molluscs, Arthropods, and Echinoderms. "Worms" lie in a central (and still muddy) pool, from which flow many streams. Lower still, and in marked contrast to the rest, are the Stinging-animals, such as jellyfish throbbing in the tide, zoophytes clustering like plants on the rocks, sea-anemones like bright flowers, corals half-smothered with lime. In the Sponges the type of architecture is often very hard to find. They form a branch of the tree of life which has many beautiful leaves, but has never risen far. Beyond this our unaided eyes will hardly lead us, yet the pond-water held between us and the light shows vague specks like living motes, the firstlings of life, the simplest animals or Protozoa, almost all of which have remained mere unit specks of living matter. It is easy to write this catalogue of the chief forms of life, and yet easier to read it : to have the tree of life as a living picture is an achievement. It is worth while to think and dream over a bird's-eye view of the animal king- dom — to secure representative specimens, to arrange them in a suitably shelver' cupboard, so that the outlines of the picture may become clear in the mind. The arrangement of animals on a genealogical or pedigree tree, which Haeckel first suggested, may be readily abused, but it has its value in presenting a vivid image of the organic unity of the animal kingdom. If the catalogue be thus realised, if the foliage come to represent animals actually known, and if an attempt be made to learn the exact nature, limits, and meaning of the several branches, the student has made one of the most important steps in the study of animal life. Much will remain indeed — to connect the living twigs with those wliv>se leaves fell off ages ago, to understand the continual renewal of the foliage by the birth of new leaves, and finally to understand how the entire tree of life grew to be what it is. 12 fl The Study of Animal Life part i 11 letters Sphenex Fig. 2 —Genealogical Ti.-,- .e Mn.,11 tranche, in tl.e centre indicate the ..lasses of "norms- ,1„ I CHAP. I The Wealth of Life 13 There is of course no doubt as to the fact that some forms of life are more complex than others. It requires no faith to allow that the firstlings or Protozoa are simpler than all the rest ; that sponges, which are more or less loose colonies of unit masses imperfectly compacted together, are in that sense simpler than jellyfish, and so on. The animals most like ourselves are more intricate and more perfectly controlled organisms than those which are obviously more remote, and associated with this perfecting of structure there is an increasing fulness and freedom of life. We may arrange all the classes in series from low to high, from simple to complex, but this will express only our most generalised conceptions. For within each class there is great variety, each has its own masterpieces. Thus the simplest animals are often cased in shells of .lint or lime whose crystalline architecture has great complexity. The simplest sponge is little more than a double-walled sack riddled by pores through which the water is lashed, but the Venus' Flower-Basket {Euplcctella\ one of the flinty sponges, has a complex system of water canals and a skeleton of flinty threads built up into a framework of marvellous intricacy and grace. The lowest insect is not much more intricate, centralised, or controlled than many a womi of the sea-shore, but the ant or the bee is a very complex self-controlled organism. More exact, therefore, than any linear series, is the image of a tree with branches springing from different levels, each branch again bearing twigs some of which rise higher than the base of the branch above. A perfect scheme of this sort might not only express the facts of structure, it might also express our notions of the blood-relationships of animals and the way in which we believe that different forms have arisen. But the wealth of form is less varied ihan at first sight appears. There is great wealth, but the coinage is very uniform. Our first impression is one of manifold variety ; but that gives place to one of marvellous plasticity when we see how structures apparently quite different are redu- cible to the same general plan. Thus, as the poet Goethe first clearly showed, the seed-leaves, root-leaves, stem-leaves, 14 The Study of Animal Life VKKt I and even he parts of the flower-sepals, petals, stamens, and carpels are m reality all leaves or appendages more or less modified for diverse work. The mouth-plrts Ta lobster are masticating legs, and a bird's wing is a modified fh^V 7 r c "^^"'■^^'^^^ ^^^'•e so far right in insisting on the fact of a few great types. Nature, Lamarck said, is never ^usque ; nor is she inventive so much as adaptive 4. Wealth of Numbers— Large numbers are so unthink- n..^ f^.^'-^'^'^^y \ census-taking is so difficult, that we need say little as to the number of different animals. The census includes far over a million living species_a total so rf. ^''^f° i ^%°"r power of realising it is concerned, It IS hardly affected when we admit that more than half are insects. To these recorded myriads, moreover, many newly-discovered forms are added every year-now by the individual workers who with fresh eye or improved micro- scope find m wayside pond or shore pool some new thine or again by great enterprises like the Challenger expedition / Exploring naturalists like Wallace and Semptr return from / tropical countries enriched with new animals from the dense forests or warm seas. Zoological Stations, notably that Si , Naples, are "register-houses" for the fauna of the neX bpuring sea, not merely as to number and form, 2t in many cases taking account of life and history as wdl Nor can we forget the stupendous roll of the extinct, to' which the zoological historians continue to add as they disentomb primitive mammals, toothed birds, giant reptiles, huge amphibians armoured fishes, gigantic cuttles, and a vast multitude of strange forms, the like of which ho longer • . Tf" °^ '^" Zoological Record, in which the literature and discoveries of each year are chronicled, the portentous size of a volume which professes to discuss with some completeness even a single sub-class, the number of special departments into which the science of zoology is divided, suggest the vast wealth of numbers at first sight so bewildering. More than two thousand years ago Aristotle recorded a total of about 500 forms, but more newfpedes may be described in a single volume of the Challenger Reports We speak about the number of the stars, yet more than one CHAP. I The Wealth of Life 15 family of insects is credited with including as many different species as there are stars to count on a clear night. But far better than any literary attempt to estimate the numerical wealth of life is some practical observation, some attempted enumeration of the inmates of your aquarium, of the tenants of some pool, or of the visitors to some meadow. The naturalist as well as the poet spoke when Goethe celebrated Nature's wealth : " In floods of life, in a storm of activity, she moves and works above and beneath, working and weaving, an endless motion, birth and death, an infinite ocean, a changeful web, a glowing life ; she plies at the roaring loom of time and weaves a living garment for God." 5. Wealth of Beauty. — To many, however, animal life is impressive not 'o much because of its amazing variety and numerical greatness, nor because of its intellectual suggestiveness and practical utility, but chiefly on account of its beauty. This is to be seen and felt rather than described or talked about. The beauty of animals, in which we all delight, is usually in form, or in colour, or in movement. Especially in the simplest animals, the beauty of form is often comparable to that of crystals ; witness the marvellous architecture in flint and lime exhibited by the marine Protozoa, whose empty shells form the ooze of the great depths. In higher animals also an almost crystalline exactness of symmetry is often apparent, but we find more frequent illustration of graceful curves in form and feature, resulting in part from strenuous and healthful exercise, which moulds the body into beauty. Not a little of the colour of animals is due to the physical nature of the skin, which is often iridescent ; much, on the other hand, is due to the possession of pig- ments, which may either be of the nature of reserve-products, and then equivalent, let us say, to jewels, or of the nature of waste-products, and thus a literal "beauty for ashes." It is often supposed that plants excel animals in colour, but alike in the number and variety of pigments the reverse is true. Then as to movement, how much there is to admire ; the birds soaring, hovering, gliding, and diving; the monkey's gymnastics ; the bat's arbitrary evolutions ; the grace of the x6 The Study of Animal Life part i fleet stag ; the dolphin gamboling in the waves ; the lithe lizards which flash across the path and are gone, and the snake flowing like a silver river : the buoyant swimming of fishes and all manner of aquatic animals ; the lobster darting backwards with a powerful tail-stroke across the pool ; the butterflies fliuing like sunbeams among the flowers. But Fig. 3.— Humming-birils {Floristiga 'iiellivora) visiting flowers. (From Belt.) are not all the delights of form and colour and movement expressed in the songs of the birds in spring ? I am quite willing to allow that this beauty is in one sense a relative quality, varying with the surroundings and education, and even ancestral history, of those who appreciate it. A flower which seems beautiful to a bee may be unattractive to a bird, a bird may choose her mate for qualities by no means winsome to human eyes, and a CHAP. I The Wealth of Life 17 dog may howl painfully at our sweet music. We call the apple - blossom and the butterfly's wings beautiful, partly because the rays of light, borne frcm them to our eyes, cause a pleasantly harmonious activity in our brains, partly because this awakens reminiscences of past pleasant experi- ences, partly for subtler reasons. Still, all heaWiy organisms are harmonious in form, and seldom if ever are their colours out of tone with their surroundings or with each other, — a fact v/hich suggests the truth of the Platonic conception that a living creature is harmonious because it is possessed by a single soul, the realisation of a single idea. The plants which seem to many eyes to have least beauty are those which have been deformed or discoloured by cultivation, or taken altogether out of their natural set- ting ; the only ugly animals are the products of domestica- tion and human interference on the one hand, or of disease on the other ; and the ugliest things are what may be called the excretions of civilisation, which are certainly not beauty for ashes, but productions by which the hues and colours of nature have been destroyed or smothered, where the natural harmony has been forcibly put out of tune — in short, where a vicious taste has insisted on becoming inventive. '■\ \ CHAPTER II THE WEB OF LIFE Dependence upon Surroundings — 2. Inter-relations of Plants and Animals — 3. Relation of Animals to the Earth — 4. NutHti', e Relations — 5. Afore Complex Interactions In the filmy web of the spider, threads delicate but firm bind part to part, so that the whole system is made one. The quivering fiy entangled in a comer betrays itself throughout the web ; often it is felt rather than seen Vy the lurking spinner. So in the substantial fabric of the world part is bound to part. In wind and weather, or in the business of our life, we are daily made aware of results whose first conditions are remote, and chains of influence not difficult to demonstrate link man to beast, and flower to insect. The more we know of our surroundings, the more we realise the fact that nature is a vast system of linkages, that isolation is impossible. I . Dependence upon SorroandinffS. — Every living body is built up of various arrangements of at least twelve "elements," viz. Oxygen, Hydrogen, Carbon, Nitrogen, Chlorine, Phosphorus, Sulphur, Magnesium, Calcium, Pot- assium, Sodium, and lion. All these elements are spread throughout the whole world. By the magic touch of life they ai-e built up into substances of great complexity and instability, substances very sensitive to impulses from, or changes in, their surroundings It may be that living matter diflfers from dead matter in no other way than thi; Th- I CHAP. II The Web of Life 19 varied forms of life crystallise out of their amorphous beginnings in a manner that we conceive to be analogous to the growth of a crystal within its solution. Further, we do not believe in a "vital force." The movements of living things are, like the moveme-i* o*" all matter, the expression of the world's energy, an I iilusu.tte the same laws; But to these matters we shall efrn in anoti.er chapter. Interesting, because of • s larply dc nned ?nd far-reaching significance, and because ihc p^^c'^tiai mass is so nearly infinitesimal, is the part played by iron in the story of life. For food-supply we are dependent upon animals and plants, and ultimately upon plants. But these cannot produce their valuable food-stuffs without the green colouring-matter in their leaves, by help of which they are able to utilise the energy of sunshine and the carbonic acid gas of the air. But this important green pigment (though itself perhaps free from any iron) cannot be fonned in the plant unless there be, as there almost always is, some iron in the soil. Thus our whole life is baseu on iron. And all our supplies of energy, our powers of doing work either with our own hands and brains, or by the use of animals, or through the application of steam, are traceable — if we follow them far enough — to the sun, which is thus the source of the energy in all creatures. 2. Inter-relations of Plants and Animals.— We often hear of the " balance of nature," a phrase of wide appli- cation, but very generally used to describe the mutual dependence of plants and animals. Every one will allow that most animals are more active than most plants, that the life of the former is on an average more intense and rapid than that of the latter. For all typical plants the materials and conditions of nutrition are found in water and salts absoibed by the roots, in carbonic acid gas absorbed by the leaves from the air, and in the energy of tlic sunlight which shines on the living matter through a screen of green pigment. Plants feed on very simple sub- stances, at a low chemical level, and their most char- acteristic transformation of energy is that by which the kinetic energy of the sunlight is changed into the potential I r f ao The Study of Animal Life PAST t energy of the complex stuffs which animals eat or which we use as fuel. But animals feed on plants or on creatures like themselves, and are thus saved the expense of build- ing up food -stuffs from crude materials. Their most characteristic transformation of energy is that by which the power of complex chemical substances is used in locomotion and work. In so working, and eventually in dying, they form waste-products— water and carbonic acid, ammonia and nitrates, and so on — which may be again utilised by plants. How often is the inaccurate statement repeated "that animals take in oxygen and give out carbonic acid, whereas plants take in carbonic acid and give out oxygen " ! This is most misleading. It contrasts two entirely dis- tinct processes — a breathing process in the animal with a feeding process in the plant. The edge is at once taken off the con rast when the student realises that plants and animals being both (though not equally) ahve, must alike breathe. As they live the living matter of both is oxi- dised, like the fat of a burning candle ; in plant, in animal, in candle, oxygen passes in, as a condition of li'"e or com- bustion, and carbonic acid gas p sses out as a waste-pro- duct. Herein there is no difference except in degree between plant and animal. Each lives, and n>ust therefore breathe. But the living of plants is less intense, therefore the breath- ing process is less marked. Moreover, in sunlight the respiration is disguised by an exactly reverse process peculiar to plants— the feeding already noticed, by which carbonic acid gas is absorbed, its carbon retained, and part of its oxygen liberated. There is an old-fashioned experiment which illustrates the "balance of nature." In a glass globe, half-filled with water, are placed some minute water-plants and water- animals. The vessel is then sealed. As both the plants and the animals are absorbing oxygen and liberating car- bonic acid gas, it seems as if the little living world enclosed in the globe would soon end in death. But, as we have seen, the plants are able in sunlight to absorb carbonic acid and liberate oxygen, and if present in sufficient numbers will 33F* ^ (.>:' CHAP. II TAg WehofLife ai I.; compensate both *or their own breathing and for that of animals. Thus ti e result within the globe need not be suffocation, but harmonious prosperity. If the minute animals ate up all the plants, they would themselves die for lack of oxygen before they had eaten up one another, while if the plants smothered all the animals they would also in turn die away. Some such contingency is apt to spoil the experiment, the end of which may be a vessel of putrid water tenanted fcr a long time by the very simple colourless plants known as Bacteria, and at last not even by them. Nevertheless the " vivarium " experinient is both theoretically and practically possible. Now in nature th^re is, indeed, no closed vivarium, for there is no isolation and there is open air, and it is an exaggeration to talk as if our life were dependent on there being u proportionate number of plants and animals in the neighbourhood. Yet the " balance of nature " is a general fact of much importance, though the economical relations of part to part over a wide area are neither rigid nor precise. We have just mentioned the very simple plants call'-d Bacteria. Like moulds or fungi, they depend upon other organisms for their food, being without the green colouring stuff so important in the life of most plants. These very minute Bacteria are almost omnipresent ; in weakly animals — and sometimes in strong ones too — they thrive and multiply and cause death. They are our deadliest foes, but we should get rid of them more easily if we had greater love of sunlight, for this is thcT most potent, as well as most economical antagonist. But it is not to point out the obvious fact that a Bacterium may kill a king that we have here spoken of this class of plants ; it is to acknowledge their beneficence. They are the great cleansers of the world. Animals die, and Bacteria convert their corpses into simple substances, restoring to the soil what the plants, on which the animals fed, originally absorbed through their roots. Bacteria thus complete a wide circle ; th»;y unite dead animal and living plant. For though many a plant thrives quite independently of animals on the raw materials of earth and air, others are demonstrably raisin^j H ■|«j 33 The Study of Animal Life PART r': the ashes of animals into a new life. A strange pat ship between Bacteria on the one hand and leguminous .md cereal plants on the other has recently been discovered. There seems much likelihood that with some plants of the orders just named Bacteria live in normal partner- ship. The legumes and cereals in question do not thrive well without their guests," nay more, it seems as if the Bacteria are able to make the free nitrogen of the air available for their hosts. 3. Relation of Animals to the Earth.— Bacteria are extremely minute organisms, however, and stories of their industry are apt to sound unreal. But this cannot be said of earthworms. For these can be readily seen and watched, and their trails across the damp footpath, or their castings on the grass of lawn and meadow, are familiar to us all. They are distributed, in some form or other, over most regions of the globe ; and an idea of their abundance may be gained by making a nocturnal expedition with a lantern to any convenient green plot, where they may be seen in great numbers, some crawling about, others, with their tails in their holes, making slow circuits in search of leaves and vegetable ddbris. Darwin estimated that there are on an average 53,000 earthworms in an acre of garden ground, that 10 tons of soil per acre pass annually through their bodies, and that they bring up mould to the surface at the rate of 3 inches thickness in fifteen years. Hensen found in his garden 64 large worm-holes in I4| square feet, and estimated the weight of the daily castings at about 2 cwts. in two and a half acres. In the open fields, how- ever, it seems to be only about half as much. But whether we take Darwin's estimate that the earthworms of England pass annually through their bodies about 320,000,000 tons of earth, or the more moderate calculations of Hensen, or our own observations in the garden, we must allow that the soil-making and soil-improving work of these animals is momentous. In Yorubaland, on the West African coast, earthworms {Siphonogaster) somewhat different from the common Lum- bricus are exceedingly numerous. From two separate square % U r ;i>,«f .iiifi^. S2^' , *tjafcsik26>-:= m-i cha;. II The Web of Life 23 feet of land chosen at random, Mr. Alvan Millson collected the worm-casts of a season and found that they weighed when dry io| lbs. At this rate about 62,233 tons of sub- soil would be brought in a year to the surface of each square mile, and it is also calculated that every particle of earth to the depth of two feet is brought to the surface once in 27 years. We do not wonder that the district is fertile and healthy. Devouring the earth as they make their holes, which are often 4 or even 6 feet deep ; bruising the particles in their gizzards, and thus liberating the minute elements of the soil ; burying leaves and devouring them at leisure ; preparing the way by their burrowing for plant roots and rain-drops, and gradually covering the surface with their castings, worms have, in th3 history of the habitable earth, been most important factors in progress. Ploughers before the plough, they have made the earth fruitful. It is fair, however, to acknowledge that vegetable mould sometimes forms inde- pendently of earthworms, that some other animals which burrow or which devour dead plants must also help in the process, and that the constant rain of atmospheric dust, as Richthofen has especially noted, must not be overlooked. In 1777, Gilbert White wrote thus of the earthworms — "The most insignificant insects and reptiles are of much more consequence and have much more influence in the economy of nature than the incurious are aware of. . . . Earthworms, though in appearance a small and despicable link in the chain of Nature, yet, if lost, would make a lamentable chasm. . . . Worms seem to be the great promoters of vegetation, which would proceed but lamely without them, by boring, perforatiny;. and loosening the soil, and rendering it pervious to rains and the litres of plants ; by drawing straws and stalks of leaves and twij^s into it ; and, most of all, by throwint; up such infinite numbers of lumps of earth called worm- casts, which, being their excrement, is a fine manure for grain and grass. Worms probably provide new soil for hills and slopes where the rain washes the earth away ; and they affect slopes piobably to avoid being flooded. . . . The earth without worms would soon l)ecome cold, hard-bound, and void of fermentation, and con- sequently sterile. . . . These hints we think proper to throw out, in order to set the inquisitive and discerning to work. A good mono- n .^tii r^ .fn- ^^•IdSRiSw'^^ 24 The Study of Animal Life PART 1 graph of worms would afford much entertainment and information hLJoryT" '""'' '"' "°"'' "P^" ^ '^^^^ ^"^ "- fieldTn natural After a while the discerning did go to work, and Hensen pubhshed an important memoir in 1877, while Darwin^ "good monograph" on the formation of vegetable mould appeared after about thirty years' observation in 1881 • and now we all say with him, - It may be doubted whether 'there prrtTnTh^h'r "V"f "''f' '^^" P'^y^^ - important a cStures." "^ """"^^ "' ^"'*^ '^''' lowly-organised Prof Drummond, while admitting the supreme imoort ance of the work of earthworms, eloquently ple'lds the Ss' Tn, ? Tul °',^^'^'^' "^"^ ^' ^" agricultural agent. TWs insect, which dwelt upon the earth long before thf true ant •s abunoant in many countries, and notably in Tropical Atrica. It ravages dead wood with great rapidity "If a man lay down to sleep with a wooden leg. it would be a heap of sawdust in the morning," while houses and decaying forest trees, furniture and fences, fall under the jaws of hf hungry Termites. These fell workers are blind and 1 ve underground ; for fear of their enemies they dare not show fac:e. and yet without coming out of their ground they cannm along" it! them'' TL" "'' ''""'l^'' ^ ^'^^J' '^'^^ '^'^ 8-""^ out earthworms, keep the soil circulating. The earth tu£ cr,Vn lief s;t:?^;::;nii^?d^ ' ^^^^^^"^ alluvium of a distZit vall'J/' " '°°''"'^ grains to swell the i:i T.*apjMBiirwi vrft ifc CHAP. II The Web of Life *l The influences of plants and animals on the earth are manifold. The sea- weeds cHng around the shores and lessen the shock of the breakers. The lichens eat slowly into the stones, sending their fine threads beneath the sur- face as thickly sometimes " as grass-roots in a meadow-land," so that the skin of the rock is gradually weathered away. On the moor the mosses form huge sponges, which mitigate floods and keep the streams flowing in days of drought. Many little plants smooth away the wrinkles on the earth's face, and adorn her with jewels ; others have caught and stored the sunshine, hidden its power in strange guise in the earth, and our hearths with their smouldering peat or glowing coal are warmed by the sunlight of ancient summers. The grass which began to grow in comparatively modern {i.e. Tertiary) times has made the earth a fit home for flocks and herds, and protects it like a garment ; the forests affect the rainfall and temper the climate, besides sheltering multi- tudes of living things, to some of whom every blow of the axe is a death-knell. Indeed, no plant from Bacterium to oak tree either lives or dies to itself, or is without its influence on earth and beast and man. There are many animals besides worms which influence the earth by no means slightly. Thus, to take the minus side of the account first, we see the crayfish and their enemies the water-vohs burrowing by the river banks and doing no little damage to the land, assisting in that process by which the surface of continents tends gradually to diminish. So along the shores in the .arder substance of the rocks there are numerous borers, like the Pholad bivalves, whose work of disintegration is individually slight, but in sum-total great. More conspicuous, however, is the work of the beavers, who, by cutting down trees, building dams, digging canals, have cleared away forests, flooded low grounds, and changed the aspect of even large tracts of country. Then, as every one knows, there are injuri- ous insects innumerable, whose influence on vegetation, on other animals, and on the prosperity of nations, is often disastrously great. But, on the other hand, animals cease not to pay their "■*«< "/a««aBsw!WKA • '-'^-<».rij^?^-'%it:i - 1 26 The Study of Animal Life PART I filial debts to mother earth. We see life rising like a mist in the sea, lowly creatures living in shells that are like mosques of lime and flint, dying in due season, and sinking gently to find a grave in the ooze. We see the submarine volcano top, which did not reach the surface of the ocean, slowly raised by the rainfall of countless small shells. Inch by inch for myriads of years, the snow-drift of dead shells fonns a patient preparation for the coral island. The tiniest, hardly bigger than the wind-blown dust, form when added together the strongest foundation in the world. The vast whale skeleton falls, but melts away till only the ear- bones are left. Of the ruthless gristly shark nothing stays but teeth. The sea-butterflies (Pteropods), with their frail shells, are mightier than these, and perhaps the microscopic atomies are strongest of all. The pile slowly rises, and the exquisite fragments are cemented into a stable foundation for the future city of corals. At length, when the height at which they can live is reached, coral germs moor themselves to the sides of the raised mound, and begin a new life on the shoulders of death. They spread in brightly coloured festoons, and have often been likened to flowers. The waste salts of their living perhaps unite with the gvpsum of the sea-water, at any rate in some way the originahy soft young corals acquire strong shells of carbonate of lime. Sluggish creatures they, living in calcareous castles of indolence ! In silence they spread, and crowd and smother one another in a struggle for stand ing-room. The dead forms, partly dissolved and cemented, become a broad and solid base for higher and higher growth. At a certain height the action of the breakers begins, great severed masses are piled up or roll down the sloping sides. Clear daylight at last is reached, the mound rises above the water. The foundations are ever broadened, as vigorously out-growing masses succumb to the brunt of the waves and tumble downwards. Within the surface -circle weathering makes a soil, and birds resting there with weary wings, or perhaps dying, leave many seeds of plants — the begin- nings of another life. The waves cast up forms of dormant life which have floated from afar, and a ter- ■" " "' ^Ei mm CHAP. 11 The Web of Life 27 restrial fauna and flora begin. It is a strange and beautiful story, dead shells of the tenderest beauty on th^ rugged shoulders of the volcano ; corals like meadow flowers on the graveyard of the ooze ; at last plants and trees, the hum of insects and the song of birds, over the coral island. 4. Nutritive Relations.— What we may call " nutritive chains " connect many forms of life — higher animals feed- ing upon lower through long series, the records of which sound like the stoty of «' The House that Jack built." On land and on the shore these series are usually short, for plants are abundant, and the carnivores feed on the vegetarians. In the open sea, where there is less vegeta- tion, and in the great depths, where there is none, carni- vore preys upon carnivore throughout long series — fish feeds upon fish, fish upon crustacean, crustacean upon worm, worm on debris. Disease or disaster in one link affects the whole chain. A parasitic insect, we are told, has killed off the wild horses and cattle in Paraguay, thereby influencing the vegetation, thereby the insects, thereby the birds. Birds of prey and small mammals — so-called "vermin" — are killed off in order to preserve the grouse, yet this interference seems in part to defeat itself by making the survival of weak and diseased birds unnaturally easy, and epidemics of grouse- disease on this account the more prevalent. A craze of vanity or gluttony leads men to slaughter small insect-eating birds, but the punishment falls unluckily on the wrong shoulders — when the insects which the birds would have kept down increase in unchecked numbers, and destroy the crops of grain and fruit. In a fuel-famine men have sometimes been forced to cut down the woods which clothe the sides of a valley, an action repented of when the rain-storms wash the hills to skeletons, when the valley .i flooded and the local climate altered, and when the birdi robbed of their shelter leave the district to be ravaged by caterpillar and fly. American entomologists have proved that the ravages of destructive insects may be checked by importing and fostering their natural enemies, and on the other hand, the sparrows which have established themselves in the States i- 1 ■ ?^^s^ 38 The Study of Animal Life PART I have in some districts driven away the titmice and thus tavoured the survival of injurious caterpillars. b. More Complex Interactions.— The flowering plants and the higher insects have grown up throughout lone ages together, in alternate influence and mutual per- fectmg. They now exhibit a notable degree of mutual dependence; the insects are adaoted for sipping the nectar from the blossoms; the flov >rs are fitted for givmg or receiving the fertilising golden dust or pollen which their visitors, often quite unconsciously, carry from plant to plant. The mouth organs of the insects have to be interpreted in relation to the flowers which thev visit; while the latter show structures which may be spoken of as the "footprints " of the insects. So exact is the mutual adaptation that Darwin ventured to prophesy from the existence of a Madagascar orchid with a nectar- spur 1 1 inches long, that a butterfly would be found in the same locality with a suctorial proboscis long enough to dram the cup ; and Forbes confirmed the prediction bv discovering the insert. As informatioii on the relations of flowers and insects is readily attainable, and as the subject will be discussed in the volume on Botany, it is sufficient here to notice that so far as we can infer from the history half hidden in the rocks, the floral wond must have received a marked impulse when bees and other flower-visiting insects appeared ; that for the successful propagation of flowering plants it is advantageous that pollen should be carried from one indi- vidual to another, in other words, that cross -fertilisation should be effected; and that, for the great majority of flowering plants, this is done through the agency of insects How plants became bright in colour, fragrant in scent, rich m nectar, we cannot here discuss ; the fact that they are so is evident, while it is also certain that insects are attracted by the colour, the scent, and the sweets. Nor can there be any hesitation in drawing the inference that the flowers which attracted insects with most success, and insects which got most out of the flowers, would, ipso facto, succeed better in life. CHAP. II The Web of Life 29 No illustration of the web of life can be better than the most familiar one, in which Darwin traced the links of influence between cats and clover. If the possible seeds in ihe flowers of the purple clover are to become real seeds, they must be fertilised by the golden dust or pollen from some adjacent clover plants. But as this pollen is uncon- sciously carried from flower to flower by the humble-bees, the propositi r 1 must be granted that the more humble-bees, the better next year's clover crop. The humble-bees, how- ever, have their enemies in the field-mice, which lose no opportunity of destroying the combs ; so that the fewer field-mice, the more humble-bees, and the better next year's clover crop. In the neighbourhood of villages, however, it is well known that the cats make as efiective war on the field-mice as the latter do on the bees. So that next year's crop of purple clover is influenced by the number of humble- bees, which varies with the number of field-mice, that is to say, with the abundance of cats ; or, to go a step farther, with the number of lonely ladies in the village. It should be noted, however, that according to Mr. James Sime there were abundant fertile clover crops in New Zealand before there were any humble-bees in that island. Indeed, many think that the necessity of cross-fertilisation has been exaggerated. Not all insects, however, are welcome visitors to plants ; there are unbidden guests who do harm. To their visits, however, there are often obstacles. Stiff hairs, impassably slippery or viscid stems, moats in which the intruders drown, and other structural peculiarities, whose origin may have had no reference to insects, often justify themselves by saving the plant. Even more interesting, however, is the preservation of some acacias and other shrubs by a bodyguard of ants, which, innocent themselves, ward off the attacks of the deadly leaf-cutters. In some cases the bodyguard has become almost hereditarily accustomed to the plants, and the plants to them, for they are found in constant companionship, and the plants exhibit structures which look almost as if they had been made as shelters for the ants. On some of our European trees similar little homes or domatia constantly occur, and shelter small f1 I: -y^ 30 The Study of Animal Life f I'ART I insects which do no harm to the trees, but cleanse them from mjurious fungi. In many ways plants are saved from the appetite of animals. The nettle has poisonous hairs ; thistles, furze, and holly are covered with spines; the hawthorn has its thorns and the rose its prickles ; some have repulsive odours ; others contain oils, acids, fer- ments, and poisons .vhich many animals dislike ; the cuckoo-pint {Arum) is full of little crystals which make our lips smart if we nibble a leaf. In our studies of plants we endeavour to find out what these qualities primarily mean to their possessors ; here we think rather of their secondary significance as protections against animals. For though snails ravage all the plants in a district ex- cept those which are repulsive, the snails are at most only the second- "^J^ ^'t t^'^^ft^'t^, -y ^f »-^in the evolu- (After Schimper.) tion of the repulsive T,, . qualities, are atif Mhf^ >nter-relations between plants and animals are agam .llustrated by the carnivorous, generally insecti- vorous plants. It is not our busine;s%o discu s the ongmal or primary import of the pitchers of pitcher-plants, CHAP. 11 The Web of Life 3> or of the mobile and sensitive leaves of Venus' \ ly-Trap ; nowadays, at any rate, insects are attracted to them, captured by them, and used. Let us take only one case, that of the common Bladderwort {Utricularid). Many of the leaflets of this plant, which floats in summer in the marsh ponJ, are modified into little bladders, so fashioned that minute " water-fleas " — which swarm in every comer of the pool — can readily enter them, but can in no wise get out again. The small entrance is guarded by a valve or door, which opens inwar-^s, but allows no egress. The little crusta- ceans are attracted by some mucilage made by the leaves, or sometimes perhaps by sheer curiosity ; they enter and cannot return ; they die, and their debris is absorbed by the leaf. Again, in regard to distribution, there are numerous relations between organisms. Spiny fruits like those of Jack-run-the-hedge adhere to animals, and are borne from place to place ; and minute water-plants and animals are carried from one watercourse to another on the muddy feet of birds. Darwin removed a ball of mud from the leg of a bird, and from it fourscore seeds germinated. Not a bird can fall to the ground and die without sending a throb through a wide circle. A conception of these chains or circles of influence is important, not only for the sake of knowledge, but also as a guide in action. Thus, to take only one instance among a hundred, it may seem a far cry from a lady's toilet-table to the African slave-trade, but when we remember the ivoiy backs of the brushes, and how the slaves are mainly used for transporting the tusks of elephants — a doomed race — from the interior to the coast, the riddle is read, and the respon- sibility is obvious. Over a ploughed field in the summer* morning we see the spider-webs in thousands glistening with mist-drops, and this is an emblem of the intricacy of the threads in the web of life — to be seen more and more as our eyes grow c'ear. Or, is not the face of nature like the surface of a gentle stream, where hundreds of dimpling circles touch and influence one another in an infinite com- plexity of action and reaction beyond the ken of the wisest ? A ■% ''4| CHAPTER III THE STRUGGLE OF LIFE I. Nature and Extent of tkeStruggl,-2. Armcur and Weaiom- 3. Different Forms of Struggle -4. Cruelty of the Stru^le I. Nature and Extent of the Struggle.— If we realise what IS meant by the "web of life," the recognition of the "struggle for existence" cannot be difficult Animals do not live m isolation, neither do they always pursue paths of peace. Nature is not iike a menagerie where beast IS separated from beast by iron bars, neither is it a mfilde such as would result if the bars of all the cages were at once removed. It is not a continuous Waterloo, nor yet an amiable compromise between weaklings The truth lies between these extremes. In most places where animals abound there is struggle. This may be silent and yet decisive, real without being very cruel, or it may be full of both noise and bloodshed. This struggle is very old ; it is older than the conflicts ^f men, older than the ravin of tooth and claw, it U as old as life. The struggle is often very keen— often for life or death. But though few animals escape experience of the battlefield— and for some there seems no discharge from this war— we must not misinterpret nature as "a continual free-fight." One naturalist says that all nature breathes a hymn of love, but he is an optimist under sunny southern •kies ; another compares nature to a huge gladiatorial show with a plethora of fighters, but he speaks as a pes- CHAP. lit The Struggle of Life simist from amid the din of individualistic competition. Nature is full of struggle and fear, but the struggle is sometimes outdone by sacrifice, and the fear is sometimes cast out by love. We must be careful to remember Darwin's proviso that he used the phrase "struggle for existence " " in a large and metaphorical sense, including the dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny." He also acknowledged the importance of mutual aid, sociability, and sympathy among animals, though he did not carefully estimate the relative importance of competition on the one hand and sociability on the other. Discussing sympathy, Darwin wrote, " In however complex a manner this feeling may have originated, as it is one of high importance to all those animals which aid and defend one another, it will have been increased through natural selection ; for those communities which included the greatest number of the most sympathetic members would flourish best, and rear the greatest number of offspring." I should be sorry to misrepresent the opinions of any man, but after considerable study of modern Darwinian literature, I feel bound to join in the protest which others have raised against a tendency to narrow Darwin's conception of "the struggle for existence," by exaggerating the occurrence of internecine competitive struggle. Thus Huxley says, " Life was a continuous free- fight, and beyond the limited and temporary relations of the family, the Hobbesian war of each against all was the normal state of existence." Against which Kropotkine maintains that this "view of natt z has as little claim to be taken as a scientific deduction as the opposite view of Rousseau, who saw in nature but love, peace, and harmony destroyed by the accession of man." ..." Rousseau has committed the error of excluding the beak-and-claw fight from his thoughts, and Huxley is committing the opposite error; but neither Rousseau's optimism nor Huxley's pessi- mism can be accepted as an impartial interpretation of nature." a. Armour and Weapons.— If you doubt the reality o 34 TJie Study of Animal Life part i of the struggle, take a survey of the different classes of animals. Ever)rwhere they brandish weapons or are forti- fied with armour. "The world," Diderot said, "is the abode of the strong." Even some of the simplest animals have offensive threads, prophetic of the poison- ous lassoes with which jellyfish and sea-anemones are equipped. Many worms have horny jaws; crustaceans have strong pincers; many insects have stings, not to speak of mouth organs like surgical instruments ; spiders give poisonous bites ; snails have burglars' files ; the cuttle- fish have strangling suckers and parrots' beaks. Among backboned animals we recall the teeth of the shark and the sword of the swordfish, the venomous fangs of serpents, the jaws of crocodiles, the beaks and talons of birds, the horns and hoofs and canines of mammals. Now we do not say that these and a hundred other weapons were from their first appearance weapons, indeed we know that most of them were aot. But they are weapons now, and just as we would conclude that there was considerable struggle in a community where every man bore a revolver, we must draw a similar inference from the offensive equipment of animals. As to armoured beasts, we remember that shells of lime or flint occur in many of the simplest animals, that most sponges are so rich in spicules that they are too gritty to be pleasant eating, that corals are polypes within shells of lime, that many wonns live in tubes, that the members of the starfish class are in varying degrees lime-clad, that crustaceans and insects are emphatically armoured animals, and that the majority of moiiuscs live in shells. So among backboned animals, how thoroi'^hly bucklered were the fishes of the old red sandstone aJ,^^inst hardly less effect- ive teeth, how the scales of modem fishes glitter, how securely the sturgeon swims with its coat of bony 'mail ! -Amphibians arc mostly weaponless and armourless, but reptiles are scaly animals par exxcllence, and the tortoise, for instance, lives in an almost impregnable citadel. Birds soar above pursuit, and mammals are swift and strong, but among the latter the armadillos liave bony shields of CHAP, in The Struggle of Life 35 marvellous strength, and hedgehog and porcupine have their hair hardened into spines and quills. Now we do not say that all these structures were from the first of the nature of armour, indeed they admit of other explanah'ons, but that they serve as armour now there can be no doubt. And just as we conclude that a man would not wear a chain shirt without due reason, so we argue from the prevalence of animal armour to the reality of struggle. For a moment let me delay to explain the two saving- clauses which I have inserted. The pincers of a crab are modified legs, the sting of a bee has probably the same origin, and it is likely that most weapons originally served some ether than offensive purpose. We hear of spears becoming pruning-hooks ; the reverse has sometimes been true alike of animals and of men. By sheer use a structure not originally a weapon became strong to slay ; for there is a profound biological truth in the French proN jrb : " A force de forger on devient forgeron" And again as to armour, it is, or was, well known that a boy's hand often smitten by the " tawse " became callous as to its epidermis. Now that callousness was not a device providential or otherwise— to save the youth from the pains of chastisement, and yet it had that effect. Hy bearing blows one naturally and necessarily becomes thick-skinned. Moreover, the epidermic callousness referred to might be acquired by work or play altogether apart from school discipline, though it might also be the effect of the blows. In the same way many structures which are most useful as armour may be the "mechanical" or natural results of what they afterwards help to obviate, or they may arise quite apart from their future significance. 3- Different Porms of Struggle.— If you ask why animals do not live at peace, I answer, more Scoitko, Why do not we ? The desires of animals conflict with those of their neighbours, hence the struggle for bread ind the competition for mates. Hunger and love solve the world's problems. Mouths have to be filled, but population tends locally and temporarily to outrun the means of subsistence, and the question "which mouths" r^w ip^^?* CHAP. Ill The Struggle of Life 37 has to be decided — sometimes by peaceful endeavour, as in migration, sometimes with teeth clenched or ravenous. Many animals are carnivorous, and must prey upon weaker forms, which do their best to resist Mates also have to be won, and lover may fight with lover till death is stronger than both. But these struggles for food and for mates are often strivings rather than strife, nor is a recognition of the frequent keenness and fierceness of the competition incon- sistent with the recognition of mutual aid, sociability, and love. There is a third form of the struggle, — that between an animal and its changeful surroundings. This also is a struggle withoit strife. Fellow competitors strive for their share of the limited means of subsistence ; between foes there is incessant thrust and parry ; in the courtship of mates tli« le are many disappointed and worsted suitors ; over all are the shears of fate — a changeful physical environment which has no mercy. An analysis of the various forms of struggle may be attempted as follows : (a) Between animals of the same kind which compete for similar food and other necessaries of life — Struggle between fellows. {b) Between animals of diffefent kinds, the one set striving to devour, the other set endeavouring to escape their foes, e.g. between carnivores and herbivores — Struggle between foes. (f) Between the rival suitors for desired mates — Struggle between rivals in love. For Food For Love For Foot- hold {(i) Between animals and changeful surround- ings — Struggle with fate. In most cases, besides the egoism or individualism, one must recognise the existence of altruism, paren, love and sacrifice, mutual aid, care for others, and sociality. 38 The Study of Animal Life PART I Before we consider these different forms of struggle, let us notice the rapid multiplication of individuals which furnishes the material for what in "a wide and meta- phorical sense " may be called a " battlefield." A single Infusorian may be the ancestor of millions by the end of a week. A female aphis, often producing one offspring per hour for days together, might in a season be the ancestor of a progeny of atomies which would weigh down five hundred millions of stout men. " The roe of a cod contains sometimes nearly ten million eg^s, and sup- posing each of these produced a young fish which arrived at maturity, the whole sea would immediately become a solid mass of closely packed codfish." The unchecked multiplication of a few mice or rabbits would soon leave no standing-room on earth. But fortunately, with the exception of the Infusorians, these multiplications do not occur. We have to thank the struggle in nature, and especially the physical environment that they do not. The fable of Mirza's bridge is continually true, — few get across. (a) It is often said that the struggle between fellows of the same kind and witli the same needs is keenest of all, but this is rather an assumption than an induction from facts. The widespread opinion is partly due to an a priori con- sideration of the problem, partly to that anthropomorphism which so easily besets us. We transfer to the animal world our own experience of keen competition with fellows of the same caste, and in so doing are probably unjust Thus Mr. Grant Allen says — " The baker does not fear the competition of the butcher in the struggle for life ; it is the competition of the other bakers that sometimes inexorably crushes him out of existence. ... In this way the great enemies of the individual herbivores are not the carnivores, but the other herbivores. ... It is not so much the battle between the tiger and the antelope, between the wolf and the bison, between the snake and the bird, that ultimately results in natural selection or survival of the fittest, as the struggle between tiger and tiger, between bison and bison, between snake and aiiakc between antelope and antelope. . . . Homo komini lupus, says the old proverb, and so, we may add, in a wider sense, lupus lupo CHAP. Ill Ike Struggle of Life 39 lupus, also. . . . The struggle i.; fierce between allici. kinds, and fiercest of all between individual members of the same species." I have quoted these sentences because they are clearly and cleverly expressed, after the manner of Grant Allen, but I do not believe that they are true statements of facts. The evidence is very unsatisfactory. In his paragraph sum- marised as "struggle for life most severe between indi- viduals and varieties of the same species ; often severe between species of the same genus," Darwin gave five illustrations : one species of swallow is said to have ousted another in North America, the missel-thrush has increased in Scotland at the expense of the song-thrush, the brown rat displaces the black rat, the small Asiatic cockroach drives its great congener before it, the hive-bee imported to Australia is rapidly exterminating the small, stingless native bee. But the cogency of these instances may be disputed : thus what is said about the thrushes is denied by Professor Newton. And on the other hand, we know that reindeer, beavers, lemming, buffaloes and many other animals migrate when the means of subsistence are unequal to the demands of the population, and there are other peaceful devices by which animals have discovered a way out of a situation in which a life-and-death struggle might seem inevitable. Very instructive is the fact that beavers, when too numerous in one locality, divide into two parties and migrate up and down stream. The old proverb which Grant Allen quotes, Homo homini lupus, appears to me a libellous inaccuracy ; the extension of the libel to the animal world has certainly not been justified by careful induction. For a discussion of the alleged competition between fellows, I refer, and that with pleasure and grati- tude, to Kropotkine's articles on '* Mutual Aid among Animals," Nineieenth Century, September and November 1890. {V) Of the struggle between foes difTering widely in kind little need be said. It is very apparent, especially in wild countries. Carnivores prey upon herbivores, which some- times unite in successful resistance. Birds of prey devour mnp 40 "V if The Study of Animal Life PART I small mammals, and sometimes have to fight hard for their booty. Reptiles also have their battles— witness the combats between snake and mongoose. In many cases, however carnivorous animals depend upon small fry; thus many birds feed on fishes, insects, and worms, and many fishes live on minute crustaceans. In such cases the term Fig. 6. -Weasel attacking a grouse. (From St. John's mid Sports.) Struggle must again be used " in a wide and metaphorical i/Mihv- sense (r) In a great number of cases there is between rival males a contest for the possession of the females,-a competition m which beauty and winsomeness are sometimes as im- portant as strength. Contrast the musical competition between rival songsters with the fierce combats of the stags CHAP. Ill The Struggle of Life 41 Many animals are not monogamous, and this causes strife ; a male seal, for instance, guards his harem with ferocity. (rf) Finally, physical nature is qui te careless of life. Changes of medium, temperature, and moisture, continually occur, and the animals flee for their lives, adapt themselves to new conditions, or perish. Cataclysms are rare, but changes are common, and especially in such schools of experience as the sea-shore we may study how vicissitude has its victims or its victors. The struggle with Fate, that is to say, with changeful surroundings, is more pleasant to contemplate than the other kinds of struggle, for at the rigid mercilessness of physical nature we shudder less than at the cruel competi- tion between living things, and we are pleased with the devices by which animals keep their foothold against wind and weather, storm and tide, drought and cold. One illus- tration must suffice : drought is common, pools are dried up, the inhabitants are left to perish. But often the organism draws itself together, sweats off a protective sheath, which is not a shroud, and waits until the rain refreshes the pools. Not the simplest animals only, but some of comparatively high degree, are thus able to survive desiccation. The simplest animals encyst, and may be blown about by the wind, but they rest where moisture moors them, and are soon as lively as ever. Leaping a long way upwards, we find that the mud- fish {Protopterus) can be transported from Africa to Northern Europe, dormant, yet alive, within its ball of clay. We do not believe in toads appear- ing out of marble mantelpieces, and a palaeontologist will but smile if you tell him of a frog which emerged from an intact piece of old red sandstone, but amphibians may remain for a long time dormant either in the mud of their native pools or in some out-of-the-way chink whither they had wandered in their fearsome youth. A shop which had once been used in the preparation of bone-dust was after prolonged emptiness reinstated in a new capacity. But it was soon fearfully infested with mites {Glyciphagus\ which had been harboured in crevices in a strange state of dry dormancy. Every mite had in a sense 49 The Study of Animal Life PART ^ s' died, but remnant cells in the body of each had clubbed together in a life-preserving union so effective that a return of prosperity was followed by a reconstitution of mites and by a plague of them. Of course great caution must be exercised with regard to all such stories, as well as in regard to the toads within stones. Of common little animals known as Rotifers, it is often said, and sometimes rightly, that they can survive prolonged desiccation. In a small pool on the top of a granite block, there flourished a family of these Rotifers. Now this little pool was period- ically swept dry by the wind, and in the hollow there remained only a scum of dust. But when the rain returned and filled the pool, there were the Rotifers as lively as ever. What inference was more natural than that the Rotifers survived the desiccation, and lay doi-mant till moisture returned.? But Professor Zacharias thought he would like to observe the actual revivification, and taking some of the dusty scum home, placed it under his micro- scope on a moist slide, and waited results. There were the corpses of the Rotifers plain enough, but they did tiot revive even in abundant moisture. What was the explanation ? The eggs of these Rotifers survived, they developed rapidly, they reinstated the family. And of course it is much easier to understand how single cells, as eggs are, could survive being dried up, while their much more complex parents perished. I do not suggest that no Rotifers can survive desiccation, it is certain that some do; but the story I have told shows the need of caution. There is no doubt, moreover, that certain simple "worms," known as "paste- eels," « vinegar-eels," etc., from their frequent occurrence in such substances, can survive desiccation for many years. Repeated experiments have shown that they can lie dormant for as long as, but not longer than, fourteen years ! and it is interesting to notice that the more prolonged the period of desiccation has been, the longer do these threadworms take to revive after moisture has been supplied. It seems as if the life retreated further and further, till at length it may retreat beyond recall. In regard to plants there are many similar facts, for though accounts of the germination CRAP. Ill The Struggle of Life 43 of seeds from the mummies of the pyramids, or from the graves of the Incas, are far from satisfactory, there is no doubt that seeds of cereals and leguminous plants may retain their life in a dormant state for years, or even for tens of years. But desiccation is only one illustration out of a score of the mariner in which animals keep their foothold against fate. I need hardly say that they are often unsuccessful ; the individual has often fearful odds against it. How many winged seeds out of a thousand reach a fit resting-place where they may germinate ? Professor Mobius says that out of a million oyster embryos only one individual grows up, a mortality due to untoward currents and surroundings, as well as to hungry mouths. Yet the average number of thistles and oysters tends to continue, " So careful of the type she seems, so careless of the single life." Yet though the average usually remains constant, there is no use trying to ignore, what Richard Jefferies sometimes exaggerated, that the physical fates are cruel to life. But how much wisdom have they drilled into us ? " For life is not as idle ore, But iron dug from central gloom, And heated hot with burning fears. And dipt in baths of hissing tears, And battered by the shocks of doom To shape and use." 4. Ornelty of the Struggle. — Opinions differ much as to the cruelty of the " struggle for existence," and the question is one of interest and importance. Alfred Russel Wallace and others try to persuade us that our ccnception of the "cruelty of nature" is an anthropomorphism; that, like Balbus, animals do not fear death ; that the rabbit rather enjoys a run before the fox ; that thrilling pain soon brings its own anaesthetic ; that violent death has its pleasures, and starvatioii its excitement. Mr. Wallace, who speaks with the authority of long and wide ex- perience, enters a vigorous protest against Professor Huxley's description of the myriads of generations of »^ 44 '' '"''^iwWIipWWMIiiii'.tii'yiiii 11 /I'm The Study of Animal Life PART I herbivorous animals "which have been tormented and devoured by carnivores " ; of both alike " subject to all the tTr"'' f"S^'?"' '° °'^ "«"' ^•^^^^' ^"d over-multiplica tion ; of the "more or less enduring suffering" which is the meed of both vanquished and victor; of the whole creation groaning in pain. "There is good reason to believe." says Mr. Wallace, " that the supposed to ments and niisenes of animals have little real existence, but are the reflection of the imagined sensations of cultivated men and women in similar circumstances, and that the amount aL'n?«t r"\ '^""'f ""' '''' ^^^"^^"'^ ^°r existence among animals ,s altogether insignificant." " Animals are spared from the pain of anticipating death ; violent deaths, f not too prolonged, are painless and easy; neither do those which die of cold or hunger suffer much the popula Idea of the struggle for existence entailing misery and paL on the animal worid is the very reverse of the tmth " ^He concludes by quoting the conclusion of Darwin's chapter on the struggle for existence: "When we reflect on this struggle, we may console ourselves with the full belief that the war of nature is not incessant, that no fear is felt ha healthy, and the happy survive and multiply." Yet i was Darwin who confessed that he found in the world "oo much misery." ^"° We have so little security in appreciating the real life- the mental and physical pain or happiness-of anima^hat there is apt to be exaggeratio. on both sides, according a a pessimistic or an optimistic mood predominates. I there fore leave It to be settled by your own observation whether' hunted and captured, dying and starving, maimed aS half frozen animals have to endure "an altogether insignificant "TuM° vT' '"''""^ '" ^^^ =^-^^'« ^- existen";?" whi^ M w n *^ """'' ''"^'"'' '^^' ^^^'^ is much truth in what Mr. Wallace urges. Moreover, the term cruelty can hardly be used with accuracy when the involved infliction less'f'ruel-rth?- • I" ""^ ^^"^ ^^^ camivoresTr IL " 1,.'° ?"L"^ '!?^ *^- - -« to our domesti- .... — - "•«" wc arc lo OU cated animals. We must also remember that the struggle CHAP. Ill The Struggle of Life 45 for existence " is often applicable only in its '* wide and metaphorical sense." And it is fair to balance the happiness and mutual helpfulness of animals against the pain and deathful competition which undoubtedly exist. What we must protest against is that one-sided inter- pretation according to which individualistic competition is nature's sole method of progress. We are told that animals have got on by their struggle for individual ends ; that they have made progress on the corpses of their fellows, by a " blood and iron " competition in which each looks ov^ for himself, and extinction besets the hindmost. To those who accept this interpretation the means employed seem justified by the results attained. But it is only in after-dinner talk that we can slur over whatever there is of pain and cruelty, overcrowding and starvation, hate and individualism, by saying complacently that they are justified in us their children; that we can rest satisfied that what has been called "a scheme of salvation for the elect by the damnation of the vast majority " is a true statement of the facts ; that we can seriously accept a one-sided account of nature's regime as a justification of our own ethical and economic practice. The conclusions, which I shall afterwards seek to substantiate, are, that the struggle for existence, with its associated natural selection, often involves cruelty, but certainly does not always do so ; that joy and happiness, helpfulness and co-operation, love and sacrifice, are also facts of nature, that they also are justified by natural selection ; that the precise nature of the means employed and ends attained must be carefully considered when we seek from the records of animal evolution support or justification for human conduct ; and that the tragic chapters in the history of animals (and of men) must be philosophically considered In such light as we can gather from what we know of the whole book. ^^^'^^ESWa^v-:. CHAPTER IV :•' SHIFTS FOR A LIVING I. Insulation -2. ConccahncH-i. Parasitism-^. General Re- semblance to Surroundings -i. Variable Colouring~6. Rat^id Chanse of Colour —t. Special Protective Resemblance -%. IVarnmg Colours -q. Mimicry— lo. Afasiimr-ii. Com- bmatton of Advantageous Qualities— 12. Surrender of Parts Granting the struggle with fellows, foes, and fate, we are led by force of sympathy as well as of logic to think of the shifts for a living which tend to be evolved in such con- ditions, and also of some other ways by which animals escape from the intensity of the struggle. I. InBUlation.— Some animals have got out of the struggle through no merit of their own, but as the result of geological changes which have insulated them from their enemies. Thus, in Cretaceous times probably ihe marsupials which inhabited the Australasian region were insulated. In that region they were then the only re- presentatives of Mammalia, and so, excepting the "native dog, some rodents and bats, and more modern imports, they still continue to be. By their insulation they were saved from that contest with stronger mammals in which all the marsupials left on the other continents were exterminated, with the exception of the opossums, which hide in American forests. A similar geological insulation accounts for the large number of lemurs in the Island of Madagascar. CHAP. IV Shifts for a Living 47 2. Ooncealment. — A change of habitat and mode of life is often as significant for animals as it is for men. It is easy to understand how mammals which passed from terrestrial to more or less aquatic life, for instance beaver and pwlar bear, seals, and perhaps whales, would enjoy a period of relative immunity after the awkward time of transition was over. So, too, many must have passed from the battlefield of the sea -shore to reLitive peace on land or in the deep-sea. In a change from open air to underground life, illustrated for instance in the mole, many animals have sought and found safety, and the change seems even now in progress, as in the New Zealand parrot S/ri/tgops, which, having lost the power of flight, has taken to burrowing. Similarly the power of flight must have helped insects, some ancient saurians, and birds out of many a scrape, though it cannot be doubted th^t this transition, and also that from diurnal to nocturnal habits, oft. brought only a temporary relief. 3. Parasitism. — i-rom the simple Protozoa up to the beginning of the backboned sei s, we find illustrations of animals which have taken to a thievish existence as unbidden guests in or on other organisms. Flukes, tapeworms, and some other " worms," many crustaceans, insects, and mites, are the most notable. Few animals are free from some kind of parasite. There are various grades of parasitism ; there arc temporr-ry and permanent, external and internal, very degenerate, and very slightly affected parasites. Some- times the adults are parasitic while the young are free-liv- ing, sometimes the reverse is true ; sometimes the parasite completes its life in one host, often it reaches maturity only after the host in which its youth has been passed is de- voured by another. In many cases the habit was probably l)cgun by the females, which seek shelter during the period of egg -laying; in not a few crustaceans and insects the females alone are parasitic. Most often, in all probability, liun;;er and the search for shelter led to the estabUshment of the thievish haLit. Now, the advantages gained by a thoroughgoing parasite are great— safety, warmth, abund- ant food, in short, "complete material well-being." But 48 The Study of Animal Life PART I there is another aspect of the case. Parasitism tends to be followed by degeneration — of appendages, food -canal, sense-organs, nervous system, and other structures, the possession and use of which make life worth living. More- over, though the reproductive system never degenerates, the odds are often many against an embryo reaching a fit host or attaining maturity. Thus Leuckart calculates that a tapeworm embryo has only about i chance in 83,000,000 of becoming a tapeworm, and one cannot be sorry that its chance is not greater. In illustration of the degenera- tion which is often associated with parasitism, and varies as the habit is more or less predominant, take the case of Sacculina—^ crustacean usually ranked along with bar- nacles and acorn-shells. It begins its life as a minute free " nauplius," with three pairs of appendages, a short food- canal, an eye, a small brain, and some other structures characteristic of many young crustaceans. In spite of this promiseful beginning, the young Sacculina becomes a para- site, first within the body, and finally under the tail, of a crab. Attached by absorptive suckers to its host, and often doing no slight damage, it degenerates into an oval sac, almost without trace of its former structure, with reproductive system alone well developed. Yet the degeneration is seldom so great as this, and it is fair to state that many parasites, especially those which remain as external hangers-on, seem to be but slightly afTccted by their laiy thievish habit ; nor can it be denied that most are well adapted to the conditions of their life. But on the whole the parasitic life tends to degeneration, and is unprogress- ive. Meredith writes of Nature's sifting " Behold the life of ease, it drifts. The sharpened life commands its course 1 She winnows, winnows roughly, sifts, To dip her chosen in her source. Contention is the vital force Whence pluck they brain, her pri«e of gifts." 4« Ckntnd Reiemblance to Snrroimdinfi. Many transparent and translucent blue animals are hardly CHAP. IV Shifts for a Living 49 visible in the sea; white animals, such as the polar bear, the arctic fox, and the ptarmigan in its winter plumage are inconspicuous upon the snow; green animals, such as insects, tree-frogs, lizards, and snakes, hide among the leaves and herbage ; tawny animals harmonise with sandy soil ; and the hare escapes detection among the clods. So do spotted animals such as snakes and leopards live unseen in the interrupted light of the forest, and the striped tiger is lost in the jungle. Even the eggs of birds are often well suited to the surroundings in which they are laid. There can be no doubt that this resemblance between the colour of an animal and that of its surroundings is sometimes of protective and also aggressive value in the struggle for existence, and where this is the case, natural selection would foster it, favouring with success those variations which were best adapted, and eliminating those which were conspicuous. But there are many instances of resemblance to sur- roundings which are hard to explain. Thus Dr. A. Seitz describes a restricted area of woodland in South Brazil, where the great majority of the insects were blue, although but a few m"!(^ off a red colour was dominant. He maintains that the facts cannot in this case be explained as due either to general protective resemblance or to mimicry. I have reduced what I had written in illustration of advantageous colouring of various kinds, because this exceedingly interesting subject has been treated in a readily available volume by one who has devoted much time and skill to its elucidation. Mr. E. B. Poulton's Colours of Animals (International Science Series, London, 1890) is a fascinating volume, for which all interested in these aspects of natural history n»ust be gra' ful. With this a forth- coming work {Animal Coloration, London, 1892) by Mr. F, E. Beddard should be compared. 5- Variable Colouring.— Some animals, such as the ptarmigan and the mountain-hare, become white in winter, and are thereby safer and warmer. In some cases it H certain that the pigmented feathers and hairs become white, in other cases the old feathers and hairs drop , TV^QJg' ■"wic^MnwB^imT-'riraTW.Tniiiju .w.^:'* so The Study of Animal Life PART I oflf and are replaced by white ones ; sometimes the whiteness is the result of both these processes. It is directly due to the formation of gas bubbles inside the hairs or feathers in sufficient quantity to antagonise the effect of .my pigment that may be present, but in the case of new growths it is not likely that any pig- ment is formed. In sc ue cases, e.g. Ross's lemming and the American hare {Lepus americanus), it has been clearly shown that the change is due to the cold. It is likely that this acts somewhat indirectly upon the skin through the nervous system. We may therefore regard the change as a variation due to the environment, and it is at least possible that the permanent whiteness of some northern animals, e.g. the polar bear, is an acquired character of similar origin. There are many objections to the theory that the winter whiteness of arctic animals arose by the accumulation of small variations in individuals which, being slightly whiter than their neighbours, became dominant by natural selection, though there can be no doubt that the whiteness, however it arose, would be conserved like other advantageous variations. To several naturalists, but above all to Mr. Poulton, we are indebted for much precise information in regard to the variable colouring of many caterpillars and chrysalides. These adjust their colours to those of the surroundmgs, and even the cocoons are sometimes harmoniously coloured. There is no doubt that the variable colouring often has protective value. Mr. Poulton experimented with the caterpillars of the peacock butterfly {Vanessa to), small tortoise-shell (Vanessa urtica\ garden whites {Pieris brassica and Pieris rapa\ and many others. Caterpillars of the small tortoise-shell in black surroundings tend to be- come darker as pupae ; in a white environment the pupx are lighter ; in gilded boxes they tend to become golden. The surrounding colour seems to influence the caterpillar " during the twenty hours immediately preceding the last twelve hours of the larval statr," "and this is probably the true meaning of the hours during which the caterpillar rests motionless on the surface upon which it will pupate. ' CHAP. IV Shifts for a Living 5> " It appears to be certain that it is the skin of the larva which is influenced by surroundinjj colours during the sensitive period, and it is probable that the cfifects are wrought through the medium of the nervous system." Accepting the facts that caterpillars are subtly affected by surrounding colours, so that the quiescent pupie har- monise with their environment, and that the adjustment has often protective value, we are led to inquire into the origin of this sensitiveness. That the change of colour is not a direct result of external influence is certain, but of the physiological nature of the changes we know little more than that it must be complex. It may be main- tained, that " the existing colours and markings are at any rate in part due to the accumulation through heredity of the indirect influence of the environment, working by means of the nervous system ; " " to which it may be replied," Poulton continues, «« that the whole use and meaning of the power of adjustment depends upon its freedom during the life of the individual ; any hereditary bias towards the colours of ancestors would at once destroy the utility of the power, which is essentially an adaptation to the fact that different individuals will probably meet with different environments. As long ago as 1873 Professor Meldola argued that this power of adjustment is adaptive, and to be explained by the operation of natural selection." Foulton's opinion seems to be, that the power of producing variable colouring arose as a constitutional variation apart from the influence of the environment, that the power was fostered in the course of natural selection, and that its limits \\ere in the same way more or less defined in adapta- tion to the most frequent habitat of the larvae before and during pupation. The other theory is that the power arose as the result of environmental influence, was accumu- ated by mheritance throughout generations, and was fostered like other profitable variations by natural selection. The question is whether the power arose in direct relation to environmental influence or not, whether external influence was or was not a primary factor in evolving the power of adapting colour, and in defining it within certain limits. f 5a The Study of Animal Life part i 6. Bapid Ohange of Oolonr. — For ages the chamaeleon has been famous for its rapid and sometimes striking changes of colour. The members of the Old World genus Chamceleo quickly change from green to brown or other tints, but rather in response to physical irrita- tion and varying moods than in relation to change of situation and surrounding colours. So the American " chamaeleons " {Anolis) change, for instance, from emerald to bronze under the influence of excitement and various kinds of light. Their sensitiveness is exquisite ; " a pass- ing cloud may cause the bright emerald to fade." Some- times they may be thus protected, for " when on the broad green leaves of the palmetto, they are with difficulty per- ceived, so exactly is the colour of the leaf counterfeited. But their dark shadow is very distinct from beneath." Most of the lizards have more or less of this colour-changing power, which depends on the contraction and expansion of the pigmented living matter of cells which lie in layers in the under-skin, and are controlled by nerves. In a widely different set of animals — the cuttle-fishes— the power of rapid colour-change is well illustrated. When a cuttle-fish in a tank is provoked, or when one almost stranded on the beach struggles to free itself, or, most beautifully, when a number swim together in strange unison, flushes of colour spread over the body. The sight suggests the blushing of higher animals, in which nervous excitement passing from the centre along the peripheral nerves influ- ences the blood-supply in the skin ; but in colour-change the nervous thrills affect the pigment-containing cells or chroma- tophores, the living matter of which contracts or expands in response to stimulus. It must be allowed that the colour- change of cuttle-fish is oftenest an expression of nervous excitement, but in some cases it helps to conceal the animals. More interesting to us at present are those cases of colour- change in which animals respond to the hues of their surroundings. This has been observed in some Amphibians, such as tree-frogs ; in many fishes, such as plaice, stickleback, minnow, trout, Goinus ruthtnsparri. . BWIWP'Jft '-<■•*?• A-iVt»SThJ» CHAP. !▼ Shifts for a Living 53 Serranus ; and in not a few crustaceans. The researches of Briicke, Lister, and Pouchet have thrown much light on the subject. Thus we know that the colour of surround- ings affects the animals through the eyes, for blind plaice, trout, and frogs do not change their tint. The nervous' thrill passes from eye to brain, and thence extends, not down the main path of impulse— the spinal cord— but down the sympathetic chain. If this be cut, the colour-change does not take place. The sympathetic" system is connected with nerves passing from the spinal cord to the skin, and it is along these that the impulse is further transmitted. The result is the contraction or expansion of the pigment in the skin-cells. Though the path by which the nervous influence passes from the eye to the skin is somewhat circuitous, the change is often very rapid. As the resulting resemblance to surroundings is often precise, there can be no doubt that the peculiarity sometimes profits its possessors. 7. Special Protective Resemblance. — The likeness between animals and their surroundings is often very precise, and includes form as well as colour. Thus some bright butter- flies, ./>,\jmis GouUit), (From Bates.) S. That the imitation, however minute, is external and visible only, never extending to internal characters or to such as do not aftect the external appearance. Many inedible butterflies are mimicked by others quite different. Many longicorn beetles exactly mimic wasps, bees, or ants. The tiger- beetles are mimicked by more harmless insects ; the common drone-fly {Eristalis) is like a bee; spiders are sometimes ant-like. Mr. Bates relates that he repeatedly shot humming-bird moths in mistake for humming-birds. Among Vertebrates genuine mimicry is rare, but it is well known that some harmless snakes mimic CHAP. IV Shifts for a Living 59 lue swollen poisonous species. Thus, the very poisonous coral-snakes {Elaps), which have very characteristic markings, are mimicked in din';i ;nt localities by several harmless forms. Similarly in regard to birds, Mr. Wallace notices that the powerful "friar-birds" {Tropidorhynckus) of Malaya are mimicked by the weak and timid orioles. *' In each of the great islands of the Austro-Malayan region t\ere is a dis- tinct species of Tropidorhynchus, -md thpr. is al^^ays along with it an oriole that exactly mimics it." That there may be mimetic resembla uc I <. - • (_n d'£tii,«.\ forms there can be no doubt, and tbt» v ii kj{ ii\^ -:».■- txw- blance has been verified ; but there ?'~ -oir.r ,;m . u ;_i,d«' .rv to weaken the case by citing instan.jt - ; j ,ii . t- = . liici liave been insuflSciently criticised. flu.- f^ i,> ;? i ,. -dlv justify us in saying that the larvae ot t'.r . .^^ lar*. tl^u.k 'Slolh {Chirrocatnpn) " terrify their en- r.ii . ' , r^> .ujij/o tion of a cobra-like serpent ; " or that the 'ob . , nluch spi'-es abrrii by the large eye-like 'specac dilated h' od, offers an appropriate model foi interior end of the caterpillar, with its terrifying markings." Th°re is only on*; theory of mimicry, namely, that among the min.icking animals varieties occurred which prospered by bei.ig somewhat like the mimicked, and that in the course of natural selection this resemblance was gradually increased until it became domirant and, in many cases, remarkably exact. As to the primary factors giving rise to the variation, we can only speculate. To begin with, indeed, there must have been a general resemblance between the ancestors of the mimicking animal and those of the mimicked, for cases like the Humming-Bird and its Doppel-Ganger moth are very rare. But this does not take us very far. The beginning of the mimetic change is usually referred to ore of those "indefinite," "fortuitous," "spontaneous" variations which are believed to be common among animals. It is logically possible that this may have been the case, and that there was at the very beginning no relation between the variation of the mimicker and the existence of the mimicked. But as illustrations of mimicry accumulate — ar.d they are already m Mi Hi 6o TJie Study of Animal Life PART I c o J £ O 1. X 'J s ; - I S§i '.--, iiiy-A r . CHAP. IV Sh'"s for a Living 6i very numerous — one ii tempted to ask whether there may not be in many cases some explanation apart from the action of natural selection upon casual changes. May not the similar surroundings and habits of mimickers and mimicked have sometimes something to do with their resemblance ; may it not be that the presence of the n 'micked has had a direct, but of course very subtle, influence on the mimickers ; is it altogrether absurd to suppose that there may be an element of consciousness in the resemblance between oriole and friar-bird ? 10. *< Masking" is one of the most interesting ways in which animals strengthen their hold on life. It is best illustrated on the sea-shore, where there is no little struggle for existence and much opportunity for device. There many animals, such as crabs, are covered by adventitious dis- guises, so that their real na«^ure is masked. Elsewhere, however, the same may be seen ; the cases of the caddis- worms — made of sand particles, small stones, minute shells, or pieces of bark — serve at once for protection and conceal- ment ; the cocoons of various caterpillars are often masked by extrinsic fragments. The nests of birds are often well disguised with moss and lichen. But among marine animals masking is more frequent. "Certain sea-urchins," Mr Poulton says, "cover themselves so completely with pebbles, bits of rock and shell, that one can see nothing but a little heap of stones ; and many marine molluscs have the same habits, accumulating sand upon the s'.'.rface of the shell, or allowing a dense growth of Algas to cover them." This masking is in many cases quite involuntar>'. Thus the freshwater snails [LytttMcrus) may be so thickly covered with Algae that they can hardly move, and some marine forms are unable to favour or prevent the growth of other orjjanisms upon their shells, but how far this is from be- injj the whole story is well known to all who are ac([uain»'!(! with our shore crabs. F"or though they also may be invol- untarily masked, there is ample evi/Apra). (Ktani Mates.) themselves. Mr. Hatesnn describes how the nah seizes a piece of weed, tears off a piece, chews the end in his moufli. and then nibs it firmly on his head and legs until it i- raugh- by the turved hairs and fi.xed " Ihe whole pri (ceding is most human and piirimseful. Many substance-, as hydroids, spong« s I'oly/oa, and weetls of many kinminetrica!!y i>!attd on c orrt^ponduK; M HA , CHAP. IV Shifts for a Living 63 parts of the body, ar.d particularly long plume-like pieces are fixed on the head." Thus, as Carus Sterne says, is the story of " Bin am's walking wood " re-enacted on the sea- shore. Furthermore, a Stenorhynchus which has been cleaned will immediately begin to clothe itself again, with the same care and precision as before. Mr. Robertson of Millport often saw Stennrhynchus longirostris — a common crab — picking about its limbs and conveying the produce to its mouth. " If other observations confirm the view that this animal is a true vegetarian, we shall have one example at least of an independent agriculturist, who is not only superior of his lands, but carries them with him when he removes." I also have seen the crab doing what " tlie naturalist of Cumbrae " observed. In further illustration of masking we may cite Dromia vulgaris, often covered with sponge ; Dromia excavata, with compound ascidians ; the Amphipod Atylus, with seaweed ; while a species of Dorippe is said to bear a bivalve shell, or even a leaf, as a shield, and another crab cuts off the tunic of a sea-squirt and hitches it on his own shoulders. Sometimes this masking serves as a warning or deterrent ; witness that hermit-crab {Pagurns cvamnsis) whose stolen shell is surrounded by a bright orange sponge (Suberiles domuncula). As this sponge is full of flinty needles, has a strong odour and a disagreeable taste, we do not wonder tint Mr. Garstang finds that fish dislike it intensely, noi ran we doubt that the hennit-crab trades on the reputation of its associate. In other cases the masking will aid in con- icalment and favour attack. To the associations of crabs and sea-anemones we shah afterwards refer. II. OombinAtion of AdTantageoiw Qualities. — Mr I'oulton describes, in illustration of the combination of many methods of defence, the case of the larva of the puss moth {Cerura vinula). It resembles the leaves of the poplar and willow on which it lives. When disturbed it assumes a terrifyinjj attitude, mimetic of a Vertebrate appearance ! The effect is heightened by the protrusion of two pink whips from the tenninal prongs of the body, anr many kinds are true to their popular name, and the C rmoKis are not less disruptive. Not only are the arms 66 The Study of Animal Life part i readily given off, but these break into many fiagments. There can be no doubt that this habit, combined with the marvellous power of regrowth which these animals possess, is of great protective value, while it is also probable in regard to both Echinoderms and some worms, that the disruption of parts may really increase the number of individuals. There is no need to enumerate all the protective habits and devices which animals exhibit. Some " feign " death, by falling in panic into a state allied to hypnotic trance, perhaps in some of the higher animals by conscious decep- tion ; others roll themselves up into balls, as in forms so different as myriapods and armadillos ; but, finally, I shall cite from Dr. Hickson's Naturalist in North Celebes one other device. '* I often saw advancing slowly over the sea- ardens, in parties of from four to six, a group of cutt -fish, swimming with an even backward movement, the inges of their mantles and their arms trembling, »»• ttei' colour gradually changing to what seemed to n nost infinite variety of hues as they passed jv. he rious beds of the sea -bottom. Then suddenly ihe would be a commotion in what was previously a cah md placid scene, the striped and speckled reef fishes wo be sen darting away in all directions, and of the cut ishef U that remained were four or five clouds of ink in t,H clftfl Iter. They had thrown dust in the eyes of some -OS* ark or voracious fish." liu. should not like to suggest the ide.i that animals are alw;» i careful and anxious, or forced to continual struggle and shift. •• They do not iweat and whine alwut their condition, They do not lie awake in the dark and weep for their sins, They do not make me sick discussing their duty to CJotl, Not one is dissatisfied, not one is demented With the mania of owning things ; Not one kneels to another, nor to his kind that lived thous.^n(b of years ago ; Not one is respectable or unhappy over the whole earth." Walt V.'iiitmak. CHAPTER V SOCIAL LIFE OF ANIMALS I. Partnerships— 2. Co-operation and Division of Labour— % Gre- gartous Life and Combined Action—/^. Beai>ers—s Bees— 6 't"?"^; ^f':^'''"-^- Evolution of Social Life-^. Advanta^res of Soaal Ltfe—io. A Note on the Social Organism — ii Conditstons The over- fed plant bears many leaves but its flowers are few ; the animal which eats too much becomes fat • and we know that within the living body one part may K'row out of proportion to the others. It seems as if organ competed with organ within the living engine, as .f one tissue outgrew its neighbors in the living web, as If there were some struggle for existence between the individual units which form the city of cells in any of the higher animals. This idea of internal competition has been elaborated by a Gennan biologist, Roux, in a work entitled 7-^^ Struggle of Parts within (he Organism, and It IS full of suggestivencss. It can be verified from our own experience ; but yet it seems strange. For we rightly '»nk of an organism as a unity in which the parts are Iranothef '" '""'"^' helpfulness, being members one Now, just as a biologist would exaggerate greatly if he maintained that the struggle of parts was tht most inv Fitant fact about an organism, so would a naturalist if he t. ill i \ I « 68 TAe Study of Animal Life pakt i Coherence and harmony and mutual helpfulness of parts— whether these be organs, tissues, or cells— are certainly facts in the life of individuals ; we have now to see how far the same is true of the larger life in which the many are considered as one. I. Partnersliips. —Animals often live together in strange partnerships. The «« beef-eater" birds {Buphagus) perch on cattle and extract grubs from the skin ; a kind of plover {Pluvianus agyptius) removes leeches and other parasites from the. back of the crocodile, and perhaps "picks his teeth," as Herodotus alleged ; the shark is attended by the pilot-fish {Naucrates ductor\ who is shielded by the shark's reputa- tion, and seems to remove parasites from his skin. Especially among marine animals, we find many almost constant associations, the meaning of which is often obscure. Two gasteropods Rhizochilus and Magilus grow along with certain corals, some barnacles are common on whales, some sponges and polypes are always found together, with- out there being in any of these cases either parasitism or partnership. But when we find a little fish living con- tentedly inside a large sea -anemone, or the little pea-crab (Pinnotheres) within the horse-mussel, the probable explana- tion is that the fish and the crab are sheltered by their hosts and share their food. They are not known to do harm, while they derive much benefit. They illustrate one kind of " commensalism," or of eating at the same table. But the association between crabs and sea -anemones affords a better illustration. One of the hermit-crabs of our coast {Pagurus f»ideauxii) has its borrowed shell always enveloped by a sea-anemone {Adamsia palliaia), and Pagimis bernJumius may be similarly cnsheathed by Adamsia rondeletii. Mobius describes two crabs from Mauritius which bear a sea-anemone on each claw, and m some other crab? a similar association occurs. It seems that in some cases the crab deliberately chooses its ally and plants it on its shell, and that it does not leave it behind at the period of shell -chanKim Deprived of its polype c-Mn- panion, one was seen to : restlessly ill at ease imtil It obtained another of the same kind. The use of the sea- CHAP. V Social Life of Animals 69 anemone as a mask to the crab — and also perhaps as aid in attack or defence — is obvious ; on the other hand, the sea-anemone is carried about by the crab and may derive food from the crumbs of its bearer's repast. Commensalism must be distinguished from parasitism, in which the one orgapism feeds upon its host, though it is quite possible that a commensal might degenerate into a parasite. Quite distinct also is that intimate partnership known as symbiosis, illustrated by the union of algoid and fungoid elements to form a lichen, or by the occurrence of minute Algae as constant internal associates and helpful partners of Radiolarians and some Coelenterates. 2. Co-operation and Division of Labour.— The idea of division of labour has been for a long time familiar to men, but its biological importance was first satisfactorily recognised by Milne-Edwards in 1827. Among the Stinging-animals there are many animal colonies, aggregates of individuals, with a common life. These begin from a single individual and are formed by prolific budding, as a hive is formed by the prolific egg- laying of a queen-bee. The mode of reproduction is asexual in the one case, sexual in the other ; the resulting individuals are physically united in the one case, psychically united in the other ; but these differences are not so great as they may at first sight appear. Many masses of coral are animal colonies, but among the members or " persons," as they are technically called, division of labour is very raie ; moreover, in the growth of coral the younger individuals often smother the older. In colonial zoophytes the arl)orescent mode of growth usually obviates crushing ; and tliere is sometimes very marked division of labour. Thus in the colony of Hydractittia polypes, which is often found Kiowing on the shells tenanted by hermit-crabs, there may be a hundred or more individuals all in organic connection. Ihe polypes are minute tubular animals, connected at their bases, and stretching out from the surface of the shell into the still water of the pool in which the hermit-crab is rciimif. But among the hundred individuals there are three or four castes, the differences between which probably ^SiSimX^. ■ I alii 1*. • I 70 T/t£ Study of Auimal Life PAR r I result from the fact that in such a large colony perfect uniformity of nutritive and other conditions is impossible. Individuals which are fundamentally and originally like one another grow to be different, and perform different func- tions according to the caste t > which they belong. Many are nutritive in form like the little freshwater Hydra— iv\m\7cc animals with an extensile body and with .1 terminal mouth wreathed round by mobile tentacles. On these the whole nutrition of tlie colony depends. Beside the>e there are reproductive " per- sons," which cannot feed, being mouthless, but secure the continuance of the species and give rise to embryos which start new colonies. Then there are Ion,;, lank, sensitive mem- bers, also mouthless, which serve as the sense-organs of tlic colony, and are of use in tlc- tccting food or danger. Wht 11 danger threatens, the polypo cower down, and there are IcU projecting small hard spines, which some regard as a fourtli Fig. t4. -Colony of lfy.i,act!,.; ; c> ^, .^i i »i i _ i abortive spines; and there are thoms On the hawthom hed^e. .ilso louK mouthlps individii.-ils j^ rccognising their utility to specialised m sensitiveness. (From ° ° ' charnVjers's h'.ncyciop. ; .iftcr All- the colony as a whole we can '"'"'>• hardly overlook the fact that their life as individuals is prarticaliy nil. trate the dark side of division of labour. They well illus- i! ■ I Ilcriwrt .^pcnrer .nnd Krnst Ilacckel Imve cxiilnincl voiy rlc.TiIy one l.tw of jir )j^rcss aiiionif those animals \v)iich form colonics. 'I'lio crmlo form nf a colciy is an ai,'::,'rij;aU of siniilat inilivi(hi.il^, the perfected colony is an intcip-aie in wliich by division of lalimir greater harmony of life li > resulted, and in which the whole colony is more thoroughly compacted into a unity. Among the Stinging- :i, CHAP. V Social Life of Animals 71 animals, we find some precise illustrations of such integrated colonies, especially in the Siphonophora of which the Portuguese Man-of-War i/'kysalia) is a good example. There is no doubt that these beautiful organisms are colonies of individuals, which in structure are all referable to a " medusoid " or jellyfish-like type. But the division of labour is so harmonious, and the compacting or oi^nisation of the colony is so thorough, that the whole moves and lives as a single organism. E. Perrier in his work entitled Les Colonies Animales (Paris, 1882), shows how organic association may lead from one grade of organisation and individuality to another, and explains very clearly how sedentary and passive life tends to develop mere aggregates, while free and active life tends to integrate the colony. With this may be compared A. Lang's interesting study on the influence of sedentary life and its connection with asexual reproduction — Das Einfluss des Festsitten (Jena, 1889). Haeckel, in his GmtrelU MorpkologU (a vols,, Berlin, 1866), was one of the first to shed a strong clear light on the difficult subject of organic individuality, its grades and its progressive complexity. To Spencer, Principles of Biology (2 vols., London, 1863-67), we owe in this connection the elucidation of the transition from aggregates to integrates, and of the lines of differentiation, i.e. the progressive complication of structure which is associated with division of lalwur. 3- Gregarious Life and Combined Action.— Most mammals are in some degree gregarious. The solitary kinds are in a distinct minority. The isolated are ex- posed to attack, the associated are saved by the wisdom of their wisest members and by that strength which union gives. Many hoofed animals, such as deer, antelopes, goats, and elephants, live in herds, which are not mere crowds, but organised bands, with definite conventions and with a power of combined resistance which often enables them to withstand the attacks of carnivores. Marmots and prairie-dogs, whose " cities " may cover vast areas, live peace- ful and prosperous lives. Monkeys furnish many illustra- tions of successful gregarious life. As individuals most of them are comparatively defenceless, and usually avoid com- ing to close quarters with their adversaries ; yet in a body tliey are formidable, and often help one another out of scrapes. Brehm tells how he encountered a troop of baboons which defied his dogs and retreated in good order up the MICROCOrY RBOUiTION TfST CHART (ANSI and ISO TEST CHART No. 2) 1.0 1^ §21 tim m^ U£ ■ 3^ 13^ IK lit u Im ■ 2.2 MM* I 2.0 1.8 .^S i /1PPLIED IIVHGE I nc 1653 Cast Main StrMt RochMter. Utw York U609 USA (716) 482 -0300 - Phon* (:'16) 288-5989 - Fo» 72 The Study of Animal Life PART I heights. A young one about six months old being left behind called loudly for aid. *' One of the largest males, a true hero, came down 3:sain from the mountain, slowly went to the young one, co.xed him, and triumphantly led him away — the dogs being too much astonished to make an attack." Fig. 15. — Chimpanzee (. ! hropopUhc. us or Troglodytts calvui). (I .uiuDuChaillu.) Many birds, such as rooks and swallows, nest together, and the sociality is citen advantageous. Kropotkine cites from Dr. Coucs an observation in regard to some little clirt"- svvallows which nested in .1 colony quite near the home of a prairie-falcon. "The little peaceful birds had no fear of their rapacious neighbour ; they did not let it even approach to their colony. They immediately surrounded it an.) » 1 m IP ^m 76 The Study of Animal Life PART I with a queen in her nuptial flight, himself to die soon after, saved at least fiom the expulsion and massacre which await all the sex when the supplies of honey run short in autumn. The queen and drones are important only so far as multiplica- tion is concerned. The sustained life of the hive is wholly in the hands of the workers, who in brains, in activity, and general equipment are greatly superior to their " queen." " The queen has lost her domestic arts, which the worker pos- sesses in a perfection never attained by the ancestral types ; while the worker has lost her maternal functions, although she still possesses the needed organs in a rudimentary state." What a busy life is theirs, gathering nectar and pollen unwearyingly, while the sunshine lasts, neatly slippinj into the secrets of the flowers or stealing their treasures by force, carrying their booty home in swift sweeping flight, often over long distances unerringly, unloading the pollen from their hind-legs and packing it into some cells of the comb, emptying out the nectar from their crop or honey- sac into store-cells, and then off again for more — s.ich is their socialised mania for getting. But, besides these •' foragers " — for the most part seniors — there are younger stay-at-home " nurses," whose labours, if less energetic, are not less essential. For it is their part to look after the grubs in their cradles, to feed them at first with a " pap " of digested nectar, and then to wean them to a diet of honey, pollen, and water ; to attend the queen, guiding her move- ments and feeding her while she lays many eggs, sometimes 2000 to 3000 eggs in a day. Mr. Cheshire, in his incom- parably careful book on Bees and Beekeeping^ laughs at the "many writers who have given the echo to a mediaeval fancy by stating that the queen is ever surrounded by a circle of dutiful subjects, reverently watching her move- ments, and liable to instant banishment upon any neglect of duty. These it was once the fashion to compare to the twelve Apostles, and, to make the ridiculous suggestion complete, their number was said to be invariably twelve ! ' But Mr. Cheshire's own account of the nurses' work, and of the whole life of the hive, is more marvellous than any mediaeval fancy. hi CHAP. V Social Life of Animals 77 We have not outlined nearly all the labours of the workers. There is the exhausting though passive labour of forming the wax which oozes out on the under-surface of the body, and then there is the marvellous comb-building, at which the bees are very neat and clever workers, though they do not deserve the reputation for mathematical insight once granted them. "Their combs," Mr. Cheshire says, "are rows of rooms unsurpassably suitable for feeding and nurtur- ing the larvae, for giving safety and seclusion during the mystic sleep of pupa-hood, for ensconcing the weary worker seeking rest, and for safely warehousing the provisions ever needed by the numerous family and by all during the winter's siege. Corridors run between, giving sufficient space for the more extensive quarters of the prospective mother, and affording every facility to the busy throng walking on the ladders the edges of their apartments supply ; while the exactions of modern hygiene are fully met by air, in its native purity, sweeping past the doorway of every inhabitant of the insect city." We shall not seek to penetrate into the more hidden mysteries of the life of bees ; for instance, " how the drones have a mother but no father," or how high feeding makes the difference between a queen and a worker. An outline of the yearly life is more appropriate. From the v/inter's rest the surviving bees reawaken when the early-flowering trees begin to blossom ; the workers engage in a *' spring cleaning," and the queen restores the reduced population by egg-laying. New supplies of food are brought in, new bees are bom, and in early summer we see the busy life in all its energy. The pressure of increased population makes itself felt, and migration or " swarming " becomes impera- tive. In due time and in fair weather " the old mother departs with the superabundance of the population." Meanwhile in the parent-hive drones have been born, and several possible queens await liberation. The first to be set free has to hold her own against newcomers, or it may be to die before one of them. The successful new queen soon becomes restless, issues forth in swift nuptial flight, is fertilised by a drone, and returns to her home to begin li * 78 The Study of AninuU Life PART 1 prolific egg-laying, and perhaps after a time to lead off another swarm. During the busy summer, when food is abundant, the lazy males are tolerated ; but when their function is fulfilled, and when the supplies become scarce, they are ruthlessly put to death. " No sooner does income fall below expenditure, than their nursing sisters turn their executioners, usually by dragging them from the hive, biting at the insertion of the wing. The drones, strong for their especial work, are, after all, as tender as they are defenceless, and but little exposure and abstinence is required to terminate their being. So thorough is the war of extermination, that no age is spared ; even drone eggs are devoured, the larvae have their juices sucked and their ' remains ' carried out — a fate in which the chrysalids are made to take part, the maxim for the moment being, He that will not work, neither shall he eat." This Lycurgan tragedy over, the equilibrium of the hive is more secure, and the winter comes. The social life of hive-bees is of peculiar interest, because it represents the climax of a series of stages. Hermann Miiller has traced the plausible history of the honey-bee from an insect like the sand -wasp, and has shown in other kinds of bees the various steps by which the pollen-gathering and nectar-collecting organs have been developed. The habits of life gradually lead up to the consummately social life of the hive. Thus Prosopis, which lays its eggs in the pith of bramble-stems ; the wood-boring Xylophaga ; and the leaf-cutting Megachile, which lines its burrows with circles ct' om rose leaves, are solitary bees. The various species of humble- or bumble-bee {Bombus), so familiarly industrious ^rom the spring, when the willows bear their catkins, till the autumn chill benumbs, are half way to the hive-bees ; for they live in societies of mother, drones, and workers during summer, while the sole surviv- ing queens hibernate in solitude. From the humble-bee, moreover, we gain this hint, thr.t the home is centred in the cradle, for it is in a nest with honey and pollen stored around the eggs that the hive seems to have begun. 6. Ants.— Even more suggestive of our own social organ- '*Me CHAP. V Socta/ Li^e ^f Animals 79 isation is the LUiputian wor\,d of the ants, who, like micro- scopic men, build bams and h^y ^p stores, divide their labour and indulge m play, wage warig and make slaves. Like the bee-hive, the ant-nest includes , three kinds of individuals- a queen mother or more than c.^e, a number of short-lived males, and a crowd of workers. ^ The queen is again pre- eminently maternal, and if we , can trust the enthusiastic observers, she is attended with k^y^i devotion, not without some judicious control. Farren white describes how the workers attend the queen m her. pe^mbulations : -They formed round her when she rested ; s-^^e showed their regard for her by gently waking over her, ot^^ers by patiently watch- mg by her and cherishing her wito^ their antenL, and in every way endeavouring to testifyl to their affectionate attachment and generous submission « Qould ventures further, alleging that «'m whatever \ apartment a queen condescends to be present, she commands obedience and respect, and a universal gladness spreacjs itself through the who e cell, which is expressed by partici ,iar acts of joy and exultation. They have a peculiar way ok cWinnmo- iAo«;«,r and standing up on their Ld legs, a'nd ,;SwXhe others. These frolics they make use of ^"oth'o^congratu- late each other when they meet, and to shuw their rLard for the queen." These are wonderful hG of assumed emotions 1 Should an indispensable queei,, Up dp«:;rn„« f« quit the nest, the workers do not hesitatt'! t ^3 l^d tn keep her by force, and to tear off her wingCg to secure her stay. It is certain at least that as the queens settle down to the labour of maternity, their wings are lo^t—Derhans in obedience to some physiological necessity. FLom th*» mnrh greater number of the wingless workers, we zxL ^JtI fnm?t that the males and mothers of the social ant^ are win/ed insects ; but this fact becomes impressive if in > «„„ „nmm.r weather we are fortunate enough to see therm alesTnd young queens leaving the nest in the nuptial flight during which fertilisation take place. Rising in th? 'j^ Xv glitter like sparks, pale into curling smoke, an^ vanish "Sometimes the swarms of a whole district hav.» y.' noticed to unite their countless myriads, and, seen at' a dis- if if-. 8o The Study of Animal Life I'AKT I Si ^\Vi. tance, produce an effect resei^tibling the flashing of the Aurora BoreaHs ; sometimes the effect is that of rainbow- hues in the spray of laughing waterfalls ; sometimes that of fire ; sometimes that of a smoke- wreath." *' Each column looks like a kind of slender metwork, and has a tremulous undulating motion. The poise emitted by myriads and myriads of these creatures does not exceed the hum of a single wasp. The sliightest zephyr disperses them."' After this midsummer d^y's delight of love, death awaits many, and sometimes mo/st. The males are at best short- lived, but the surviving /queens, settling down, may begin ^--^!^ FiG. 17.— Sauba aiyts at work ; to the left below, an ordinary worker ; to the right a large-headyd worker ; above, a subterranean worker. (From Hates.) to form nests, jgathering a troop of workers, or sometimes proceeding alojne to found a colony. A caste o.f workers {i.e. normally non -reproductive females) disti/nct from the males and queens, involves, nf course, some J division of labour ; but there is more tliau this. Worke/rs of different ages perform different tasks — foraging or /lousekeeping, fighting or nursing, as the case may be ; amd just as the various human occupations lea\ e marks botln for good and ill in those who follow them, so the divisybn of labour among ants is associated with differ- ences ofif structure. Thus, in the Saiiba or Umbrella Ant of ^rdizW JyCEcodof/ia ccpJialotcs\ so well described by Bates in / / CHAP. V Social Lt/e of Aninuds 8i \ix% Naturalist on the Amazons, there are three classes of workers. All the destructive labour of cutting sixpence-like disks froin the leaves of trees is done by individuals with smal heads, while others wiifh enormously large heads simply walk about looking on. These «« worker-majors " are not soldiers, nor is there \any need for supervising office.3. "I think," Bates say^/.hey would be, on this vievv, a kind ofpzkes de resistance, sf^rving as a foil against onslaughts made on the main body of workers." The third order of workers includes very .strange fellows, with he same kind of head as the worker-majors have, but "the ront IS clothed with hairs instead of b-eing polished, and hey have in the middle of the forehead a^win simple n' ; /.T^ °^ '^^ ^^^"'■^ P°^^^^s«- Among the honey ants {Myrmecocystus mexicanus) .described by Dr M'Cook from the "Garden of the Gods "tin Colorado, the division of labour is almost like a joke*. The woiers fn!r-??u^^" ^'T '''^^'" ^^"^' and discharge their spoils mto the mouths of some of their stay-at-home fellows These passive " honey-pots " store it up, till' the abdomen becomes tense and round like a grape, but e^ventuaUy they have even more tantalisingly to disgorge it foV other mem- exhibited, as Forel has shown, by many sp^^cies of ants. The hungry apply to the full for food, anld get it. A reiusal is said to be sometimes punished by de;ath » Marvellous in peace, the ants may also ^practise the anti-social "art of war," sometimes against i^other com! ™rbl^>TrP"'"' --times lith other kind" and^^. H . ''^^'^y '^y^' "^^^^ ^"'^^ b^^" c-^lebrated; fmnn ^^l °^.*^'"'' ^' '^ '* ^^'^ ^" event o{f the firs mportance, has been formally recorded." ^neas x Sylvius S TJS X^"^ circumstantial account of one contested the tn^I obstinacy between a great and small species on the tnmk of a pear tree, gravely states, "This actioA was G \ ; i i.\. >', ' ." t- El fr : I'S^ g '.Ms L MMM '■d w ''ia ^ fl B ■i M i*.' 'im 83 TAe Study of /animal Life part i fought in the pontificate of Eufenius IV., in the presence of Nicholas Pistoriensis, an eminent lawyer, who related the whole history of the battle w«th the greatest fidelity." In the fray the combatants are thoroughly absorbed, yet at a little distance other worker's are uninterruptedly Heading their daily paths ; the mel^;e is intense, yet every ant seems to know those of its own j/party ; the result of it all is often nothing. We laugh at tK>e ants— the laugh comes back on ourselves. / In some cases an ex/pedition has the definite end of slave- making, as is known ,^^0 be true of Formica sanguinea—s. British species, and oi j°olyergus rufescens, found on the Con- tinent. The former c/aptures the larvae of Formica fusca, carries them home, /and owns them henceforth as well- treated slaves ; whjfie the Amazon Ant {Polyergus) draws its supply from t >oth F. fusca and F. cunicularia, and seems to have be come almost dependent on its captives. Indeed, Huber sa ys that he never knew the Amazons take nourishment but / from the mouth of the negro captives ; while Lubbock riotes that every transition exists between bold and active b/)aron-like marauders and enervated masters, who are virtuallly helpless parasites upon their slaves— a suggestive illusjtration of laziness outwitting itself. Slaves som-'ewhat painfully suggest domesticated animals, and these ar e also to be found among ants. For what Linnjeus said long ago, that the ants went up trees to " milk their cows, th e Aphides," is true. The ants tickle these little plant-lice wit' h their antennae, and lick the juice \vhich oozes from them ; 'nay more, according to some, they inclose and tend these , -milch kine, and even breed them at home. Seed-harves 'ting and the like may be fairly called agricul- tural, and d' o not the leaf-cutters grow mushrooms, or at least feed 'on the fungi which 2^iow on the leaves, stored some say '" with that end in view ? The driver ants, "whose "dread is upon every living thing," when they are on 'the stampede, remind us of the ancient troops of non:Aad hunters, though some of them are blind. Thus there/ are hunting, agricultural, and pastoral ants — three type/vs, as Lubbock remarks, offering a strange analogy / CHAF. V Social Life of Animais H to^the three great phases in the history of human develop- Very quaint is another habit of thi. "little people, so hZt" T-r'' ^^"' °?''P^"^ °^ ^°^^^^^'^^ guests in'the home These are mostly little beetles, and have been carefiilly studied by Dr. Weismann, who distinguishes trSe guests {Atemeles, Lomechusa, Claviger) which are caredTor and fed by the ants, from others {Dinarda, H^^terius Form^oxenu^ wh.ch are tolerated, though not Ireated whh special fnendlmess, and which feed on dead ants or vege table debris ; while a third set are tolerated-like mice in our houses-only because they cannot be readily tumTout Z^l^ ^'""'f ^T'''' '^^ ''^'' ^"°^" '^ ^^^'«^^-^, a lively an mal, constantly moving its feelers, and experimenting with everything. If one be attacked by a hostile ant k ut i/^htis?","' '-^ ^"^^^°"'^^ '^y -^--'y --S e but If this IS hopeless it emits a strong odour, which seems to narcotise the ant. These little^ familiarr are reX dependent upon their hosts, who feed them and get caresses in return. It is easy to understand the presence are pets, taken away by the owners when there is a flitting relations, since they can be shifted from one nest to another, or even from spe-.ies to species. It seems hkev ;rfre mo-^^"!? ^TT^ '""I ''^'^ semi-d;rsuS I cannot Img.-r longer over the interestin? character tu^e r^h'""'" V"""'" ''"' '" '^'^ of'theirS: lecture, oi their roads, tunnels, bridges and rnv^r^H r:Lh,ed''ofT-'°' "■' r??' -" --'^« -" f° me aisabled, of their proverbial industry, and vet of th.ir * tf r itr\°eTan'?z"ci';i:rj;^ trr r C^tht? *^"^ ''^ "^'^ n.mi„n're"de«sf oraZ; 3i > m 84 The Study of Animal Life part i about their power of recognising their fellow-citizens (even when intoxicated), and of communicating definite impres- sions to one another by a subtle language of touch and gesture ; or about their instincts and intelligence, and the limitations of these. But it will be better to read some of the detailed observations, endeavouring, though necessarily with slight success, to think into the nature of ants, — their pertinacity, their indomitable "pluck," their tireless in- dustry, their organic sociality. Surely all will agree with Sir John Lubbock, to whose patient observations we ewe so much, that, "when we see an ant-hill, tenanted by- thousands of industrious inhabitants, excavating chambers, forming tunnels, making roads, guarding their home, gathering food, feeding the young, tending their domestic animals, each one fulfilling its duties industriously and without confusion, it is difficult altogether to deny them the gift of reason," or, perhaps more accurately, intelligence, for we cannot rscape the conviction •* that their mental powers differ hum those of men not so much in kind as in degree." Kropotkine says that the work of ants is performed "according to the principles of voluntary mutual aid." " Mutual aid within the community, self-devotion grown into a habit, and very often self-sacrifice for the common wel- fare, are the rule." The marvels of their history are " the natural outcome of the mutual aid which they practise at every stage of their busy and laborious lives." To this mode of life is also due " the immense development of indi- vidual initiative." Ants are not well protected, but *' their force is in mutual support and mutual confidence." " And if the ant stands at the very top of the whole class of In- sects for its intellectual capacities; if its courage is only equalled by the most courageous Vertebrates, and if its brain~to use Darwin's words— * is one of the most mar- vellous atoms of matter in the world, perhaps more so tlian the brain of man,' is it not due to the fact that mutual aid has entirely taken the place of mutual struggle in the com- munities of ants ? " 7. Ttrmites. — The true ants are so supremely interest- iilit ik^ CHAP. ▼ Social Life of Animals 85 ing, that the Termites or « white ants " (which are not ants at all) are apt to receive scant justice. Perhaps inferior in intel- ligence, they have the precedence of greater antiquity and all the interest which attaches to an old-established society Nor IS their importance less either to practical men or to speculative biologists. In 1781 Smeathman gave some account of their economy, noting that there were in everv spec.es three castes, "first, the working insects, which, for brevity, I shall generally call labourers-, next, the fighting m^sox soldters, which do no kind of labour ; and, last of all, the wmged ones, or perfect insects, which are male and female, and capable of propagation " The "workers," blind and wingless, and smallest in the ant-hill, do all the work of foraging and mining, attending the royal pair and nursing the young. The soldiers, also blind and wingless, are much larger than the workers, but diere are relatively only a few in each hill. « They stand " Prof Drummond says, "or promenade about as sentries, it the mouths of the tunnels. When danger threatens, in the shape of true ants, the soldier termite advances to the fight " With a few sweeps of its scythe-like jaws it clears the thai 'work'"' A?/ ""^^^-j?- ^^ '^e fray, quietly Continue vhnL 7 / "'"^', '" '^^ ^"^■^•"' ^'^"^ "P i" a chamber whose door admits workers but is much too small for the enants to pass out if they would, a fortunate investigator ome times finds the royal pair. The male is sometimes though by no means extraordinary. The queen-mother oTxTcits' ;7 T"^^°^^^"•^"^• ''^•^ -easur's two to SIX inches while the worker is only about a fifth of an witr iS • ^"^^ \'' T'^ '''' ''''' '-^"^ ^^^ -- '-" Drt of it K% ' ^'^"^ ^^''^ ^'■"PP^^ ^fl^- The hind ^iLi ^ K^^ 's enormously distended with eggs, and the head bears about the same proportion to the rest of m n.5^ V. • ^" ^^' P^''''''^>' ^"'J " phenomenal cor- -^'' h ' ' V T 1 ''''^'''''' -^-'^'*-^"»* of femaleness a Iari,e. cylindrical package, in shape like a sausage, j 1 1 J. Wk \ ' iVj M Ml ''1911 86 The Study of Animal Life PART I and as white as a bolster." But have some admiration for her: she sometimes lays 60 eggs per minute, or 80,000 in a day, and continues reproducing for months. As she lays, she is assiduously fed by the nursing-workers, while the eggs are carried off to be hatched in the nurseries. At the breeding season, numerous winged males and females leave Fig. 18.— Diagrammalic section of a termite's iie»t (after Houssay). In tin- walls there are winiliiig passajjes (/) ; uppermost is a well-aired empty aliii' (D) the next story (C) is a nursery where the young termites are hatclicil mi shelves (r») and (*) ; the next is a hall (H) snpporte) in which the kinjj and queen are imprisoned ; aniuiul this the chambers of workcr-tcrniites (v) and some store chambers (/'.); excavated in the grnuiul arc holes (i) out of which the materi.d umcI in making the termitary was dug. 'J'he whole structure is sometimes lu-is feet in height. the hill and its workers in swarms, most of them simply 10 die, others to mats with individuals from another hill and to begin to form new colonics. The plot of the story becomes more intricate, however, when we notice Fritz Miiller's observations, that " besides CHAP. V Social Life of Animals 87 the winged males and females which are produced in vast numbers, and which, leaving the termitary in large swarms, may intercross with those produced in other communities, there are (in some if not all of the species) wingless males and females which never leave the termitary where they are born, and which replace the winged males or females whenever a community does not find, in due time, a true king or queen." There is no doubt as to the existence of both winged and wingless royal pairs. According to Grassi, the former fly away in spring, the others ascend the throne in summer. The complementary kings or viceroys die before winter ; their mates live on, widowed but still maternal, till at least the next summer. This replacement of royalty reminds us that hive bees, bereft 0/ their queen, will rear one from the indifferent grub, but the termites with which we are best acquainted seem almost always to have a reserve of reproductive members. This other difference between termites and ants or bees should be noticed, that in the latter the "workers" are highly-developed, though sterile females, while in the former the workers seem to be arrested forms of both sexes. They are children which do not grow up. 8. Evolution of Social Life.— To Professor Alfred Espinas both naturalists and sociologists are greatly in debted for his careful discussion of the social life of animals. It may be useful, therefore, to give an outline of the mode of treatment followed in his work — Des Sodith Animates : Etude de Psychologic Compart'e (Paris, 1877) : Co-operation, which is an essential characteristic of all society, implies some degree of organic afT.nity. There are, indeed,' occasional associations between unrelated forms—" mutualism," in which both associates are benefited; "commensalism," in which »he benefit is mainly one-sided ; parasitism, which is distinctly anti-social, deteriorating the host and also the rank of the tempor- arily benefited parasite. Of normal societies whose members are mutually dependent, two kinds may be distinguished— (a) the organically connected colonies of animals, in which there is a common nutritive life ; {b) those associations which owe their origin nnd meaning to reproduction. Of the latter, some do not become more than domestic, and these are distinguished as conjugal (in 3.. i \M r! K M 1 1 i t fi J 'I'l ijL \\r,: 'ii;:; r : ii '.1 I I . 88 T/ie Study of Animal Life PART 1 whi h the parents alone are concerned), maternal (in wliich the mother is the head of the family), and paternal (in which the male becomes prominent). But higher than the pair and the family is what Espinas calls the "peuplade," what we usually call the society, whose bonds are, for the most part, psychical. But 'et us consider this problem of the evolution of sociality. The body of every animal — whether sponge or mammal — is a city of living units or cells. But there are far simpler animals than sponges. The very simplest animals, which we call firstlings or Protozoa, differ from all the rest, in being themselves units. The simplest animals are single cells ; each is comparable to one of the myriad units which make up a sponge, a coral, a worm, a bird, a man. Here, therefore, there is an apparent gulf. The simplest animals are units — single cells ; all other animals are com- binations of units — cities of cells. How is this gulf to be bridged ? It is strange that evolutionists have not thought more about this, for on the transition from a unit to" a com- bination of units the possibility of higher life depends. Every higher animal begins its individual life as a single cell, comparable to one of the firstlings. This single cell, or egg-cell, divides ; so do most of the Protozoa. But when a Protozoon divides, the results separate and live in- dependent lives ; when an egg- cell divides, the results of division cohere. Therefore, the whole life of higher animals depends upon a coherence of units. But how did this begin ? What of the gulf between single-celled Protozoa and all the other animals which arc many-celled .'' Fortunately we are not left to mere specula- tion. The gu'*" has been bridged, else we should not exist ; but, more than 'hat, the bridge, or part of it, is still left. There are a few > ^ the simplest animals which form loose colonies of units, wnich, when they divide, remain together. Whether it was through weakness, as I am inclined to believe, that the transition forms between Protozoa and higher animals became strong, or for some hidden reason, we do not know. Some speak of this coherence of firstlings as a primal illustration of organic ;issociation, CHAP. V Social Life of Animals 89 co-operation, surrender of individuality, of sociality at a low level, but it is unwise to apply these words to creatures so simple. All that we certainly knov/ is that some of the simplest animals form loose colonies of units, that the gulf between them and the higher animals is thus bridged, and that the bridging depends on coherence. Our first con- (.:>=a>^ ".• !<>•— Siphonophore colony, showing the float ( pes usually classed as "H% % ifsi 90 The Study of Animal Life part i «* worms," we see that the habit of forming colonies is common. Every sponge is a simple sac to begin with, but it buds off others like itself, and the result is a coherent colony. A zoophyte is not one individual, but a connected colony of individuals. Throughout the colony there is one life ; all the individuals have a common origin, and all are members one of another. In varying degrees of perfection the life of the whole is unified. Moreover, the unity is often increased, not diminished, by the fact that the indivi- duals are not all alike. There is division of labour among them; some may feed while others reproduce, some feel much while others may be quite callous. Thus, as we already mentioned, the Portuguese Man-of-War, a colony of small jellyfish -like individuals, has much division of labour, and yet there is much, though by no means perfect, unity of life. Our second conclusion is that among many animals- beginning with sponges and ending with the searsquirts, which are acknowledged to be animals of high degree— the habit of forming colonies is common, and that these colonies, though organically continuous, illustrate the essence of society ; for in them many individuals of common descent and nature are united in mutual dependence and help- fulness. The next step towards an understanding of the social relations of animals is very different from that in which we have recognised the habit of forming colonies. The factor which we have now to acknowledge is the love of mates. This also has its history, this also has its prophecies among the firstlings, but we shall simply assume as a fact that among crustaceans and insects first, in fishes and amphi- bians afterwards, in reptiles too, but most conspicuously among birds and mammals, the males are attracted to. the females, and in varying degrees of perfection enter into relations of mutual helpfulness. The relations and the attractions may be crude enough to begin with, but perhaps even we hardly know to what heights of devotion their highest expressions may attain. To mere physical fondness are added subtler attractions of sight and hearing, and CHAP. V Social Life of Animals 9> these are sublimed in birds and mammals to what we call love. This love of mates broadens out ; it laps the family in its folds ; it diffuses itself as a saturating influence through the societies of animals and of men. ** Sociability," Espinas says, " is based on the friendliness of mates." The fourth step is the evolution of the family. From monkeys and beavers and many kinds of birds, to ants and bees and diverse insects, many animals illustrate family life. There is no longer the physical continuity charac- teristic of the colony, but there is a growing psychical unity. It is natural that the first ties of family life should be those between mother and young, and should be strong- est when the number of offspring is not very large. But even in some beetles, and more notably in certain fishes and amphibians, the males exhibit parental care and affec- tion ; while in higher animals, especially among birds, the parents often divide the labours of the family. " Children," Lucretius said, "children with their caresses broke down the haughty temper of parents." The fifth step is the combination of families into a society, such as we find illustrated by monkeys and beavers, cranes and parrots, and in great perfection by ants. The members are less nearly related than in the family, but there may be even more unity of spirit. I do not say that it is easy to understand how coherence of units led to the formation of a " body," how colonies became integrated and the labours of life more and more distributed, how love was evolved from apparently crude attractions between the sexes, how the love of mates was broadened into parental and filial affection, or how families well knit together formed the sure foundations of society ; but I believe that it is useful to recognise these steps in the history. We hardly know how to express ourselves in regard to the origin of affection. But I cannot get beyond Aristotle's fundamental principle of evolution, that there is nothing in the end which was not also in the beginning. Yet we may fairly say that the sociality and helpfulness of animals are flowers whose roots are in kinship. Off- m ■ JS'i 13 r/; :i3 lii ; 9* The Study of Animal Life PART 1 spring are continuous in nature with their parents ; the family has a unity though its members be discontinuous and scattered ; "the race is one and the individual many." 9. Advantages of Social Life. — But animals are social, not only because they love one another, but also because sociahty is justified of her children. " The world is the abode of the strong," but it is also the home of the loving ; " contention is the vital force," but the struggle is modified and ennobled by sociality. (a) Darwin^s Position. — Darwin observed that "the individuals which took the greatest pleasure in society would best escape various dangers ; while those that cared least for their comrades, and lived solitary, would perish in greater numbers." He distinctly emphasised that the phrase "the struggle for existence" was to be used in a wide and metaphorical sense — to include all the endeavours which animals make both selfishly and un- selfishly to strengthen their foothold and that of their offspring. But he was not always successful in retaining this broad view, nor was he led to compute with sufficient care to what extent mutual aid is a factor in evolution counteractive of individualistic struggle. Without losing sight of the reality of the struggle for existence ; without disputing the importance of natural selection as a condition of evolution — securing that the relatively fittest changes succeed ; without ignoring what seems almost a truism, that love and social sympathies have also been fostered in the course of natural selection ; we maintain— (i) that many of the greatest steps of progress — such as those involved in the existence of many -celled animals, loving mates, family life, mammalian motherhood, and societies — were not made by the natural selection of indefinite variations ; (2) that affection, co-operation, mutual helpfulness, sociality, have modified the struggle for material subsistence by lessening its intensity and by ennobling its character. (b) Kropotkitte's Posilion.—hgaSnst. Prof. Huxley's con- clusion that " Life was a continual free- fight, and beyond the limited and temporary relations of the family the I CHAF. V Social Life of Animals 93 Hobbesian war of each against all was the normal slate of existence," let me place that of Kropotkine, to whose admir- able discussion of mutual aid among animals I again acknowledge my indebtedness. " Life in societies is no exception in the animal world. It is the rule, the law of nature, and it reaches its fullest development with the higher Vertebrates. Those species which live solitary, or in small families only, are relatively few, and their numbers are limited. . . . Life in societies enables the feeblest mammals to resist, or to protect them- selves from, the most terrible birds and beasts of prey ; it permits longevity ; it enables the species to rear its pro- geny with the least waste of energy, and to maintain its numbers, albeit with a very slow birth-rate ; it enables the gregarious animals to migrate in search of new abodes. Therefore, while fully admitting that force, swiftness, pro- tective colours, cunning, and endurance of hunger and cold, which are mentioned by Darwin and Wallace as so many qualities making the individual or the species the fittest under certain circumstances, we maintain that under any circumstances sociability is the greatest advantage in the struggle for life. . . The fittest are thus the most soci- able animals, and sociability appears as the chief factor ot evolution, both directly, by securing the well-being of the species while diminishing the waste of energy, and indirectly by favouring the growth of intelligence. . . . Therefore combine — practise mutual aid ! That is the surest means for giving to each and to all the greatest safety, the best guarantee of existence and progress — bodily, intellectual, and r.ioral. That is what nature teaches us." lo. A Note on "The Social Organism." — It is com- mon nowadays to speak of society as " the social organism," and the metaphor is not only suggestive but convpnient — suggestive because it is profitable to biologist and soci- ologist alike to follow out the analogies between an organism and society, convenient because there is among organisms — in aggregates like sponges, in perfected integrates Ike birds — a variety sufficient to meet all grades and views of society, and because biologists differ almost as much in 1 4 m 94 The Study of Animal Life part i their conceptions of an " organism " as sociologists do in regard to ** society." It may be questioned, ho\ ever, whether we need any other designation for society than the word society sup- plies, and whether the biological metaphor, with physical associations still clinging to it, is not more illusory than help- ful. For the true analogy is not between society and an individual organism, but between human society and those incipient societies which were before man was. Human society is, or ought to be, an integrate — a spiritual integrate of organisms, of which the bee-hive and the ants' nest, the community of beavers and the company of monkeys, are like far-oflf prophecies. And in these, as in our own societies, the modem conception of heredity leads us to recognise that there is a very real unity even between members physically discontinuous. The peculiarity of human society, as distinguished from animal societies, depends mainly on the fact that man is a social person, and knows himself as such. Man is the realis- ation of antecedent societies, and it is man's realisation of himself as a social person which makes human society what it is, and gives us a promise of what it will be. As bio- logists, and perhaps as philosophers, we are led to conclude that man is determined by that whole of which he is a part, and yet that his life is social freedom ; that society is the means of his development, and at the same time its end ; that man has to some extent realised himself in society, and that society has been to some extent realised in man. But I am slow to suppose that we, who in our ignorance and lack of coherence are like the humbler cells of a great body, have any adequate conception of the social organism of which we form part. II. Conclusions. — I would in the main agree with Kropotkine that " sociability is as much a law of nature as mutual struggle " ; with Espinas that " Le milieu social est la condition ndcessaire de la conservation et du renouvelle- ment de la vie"; and with Rousseau that "man did ait make society, but society made man." CHAPTER VI THE DOMESTIC LIFE OF ANIMALS I. The Love cf Mates — 2. Love and Care for Offspring Winter in our northern climate sets a spell upon life. The migrant birds escape from it, but most living things have to remain spell-bound, some hiding with the supreme patience of animals, others slumbering peacefully, others in a state of " lat ife " stranger than death. But within the hard rind of e trees, or lapped round by bud scales, or imprisoned within the husks of buried see ' '^ life of plants is ready to spring forth when the south wi. ' iws ; beneath the snow lie the caterpillars of summer butterflies, the frogs are waiting in the mud uf the pond, the hedgehog curled up sleeps soundly, and everywhere, under the seeming death, life rests until the spring. '* For the coming of Ormuzd, the Light and Life Bringer, the leaf slept folded, the butterfly was hidden, the germ concealed, while the sun swept upwards towards Aries." But when spring does come, heralded by r*- turning migrants — swallows and cuckoos among the n- t — how marvellous is the reawakening ! The buds swell a J burst, the corn sends up its light green shoots, the primrose and celandine are in blossom, the mother humble-bee conies out from her hiding-place and booms towards the willow catkins, the frogs croak and pair, none the worse of their fast, the rooks caw noisily, and the cooing of the dove is heard from the wood. Then, as the pale flowers are sue- 96 The Study of Animal Life part i ceeded by those of brighter tints, as the snowy hawthorn gives place to the laburnum's " dropping wells of fire " and the bloom of the lilac, the butterflies flit in the sunshine, the chorus of birds grows stronger, and the lambs bleat in the valley. Temperature rises, colours brighten, life becomes strong and lusty, and the earth is filled with love. I. The Love of Mates.— In human life one of the most complex musical chords is the love of mates, in the higher forms of which we distinguish three notes — physical, emotional, and intellectual attraction. The love of animals, however, we can only roughly gauge by analogy; our knowledge is not sure enough to appreci- ate it justly, though we know beyond any doubt that in many the physical fondness of one sex for another is sub- limed by the addition of subtler emotional syinpathies. Among mammals, which frequently pair in spring, the males are often transformed by passion, the " tirnid " I.. becomes an excited combatant with his rivals, while in t' beasts of prey love often proves itself stronger than hunger. There is much ferocity in mammalian courtship— savage jealousy of rivals, mortal struggles between them, and suc- cess in wooing to the strongest. In many cases the love- making is like a storm— violent but passing. The animals pair and separate— the females to motherhood, the males to their ordinary life. A few, like some small antelopes, seem to remain as mates from year to year ; many monkeys are said to be monogamous ; but this is not the way of the majority. Birds are more emotional than mammals, and their love- making is more refined. The males are almost always more decorative than their mates, and excel in the power of song. They may sing, it is true, from sheer gladness of heart, from a genuine joy of life, and their lay rises "like the sap in the bough"; b.t the main motive of their music is certainly love. It may not always be music to us, but it is sweet to the ears for which it is meant— to which in many tones the song says ever " Hither, my love ! Here I am ! Here ! " Nor do the male birds woo by singing alone, but by love dances and by fluttering displays • i CHAP. VI The Domestic Life of Animals \ h'M 97 -,!l.i. i.,1, I^'SWA I. -t^ ^t) v( S J n l« E I ■9 2 ^^^Pi^^, r,-«! wf.><>Jj^ \' y\ ™J\"W' if) /I V o I (3 H The Study of Animal Life PART I i >. 98 of their bright plumage ; with flowers, bright pods, and I • i\hells the bower-birds decorate tents of love for :S hUytool The mammals woo chiefly by force ; the Wrds arToften moved to love by beauty, and mates often hven prolonged partnership with mutual dehght and help- fulness ^xty years before Darwin elaborated h.s theory of exual selection'according to which males have grown more auractive because the most captivating svutors were mos sucSul in 'ove. the omitholorist Bechstem noted how the female canary or finch would choose the best smger among a^rowd oTsIitors ; and there seems some reason to beheve ^ha^The female's Choice of the most --ca^ or tne .^^^^^^ handsome has been a factor m progress. Wallace on he contrar^ maintains that the females are plamly dressed because of the fate which has befallen the conspicuous durmg Sation and surely they must thus be handicapped. To others it s;ems more natural to admit that there ts truth ,n both Darwin's and Wallace's conclusions, bufto regard ,1 c ml^es as stronger, handsomer, or more musical sinM;! because hey are males, of more active constitutional hab.t ?han their mates. To this view Mr Wallace himself mchnes, clpard w th the lion', thundei, the elephant's trunv oetS or the stag's resonant bass, and the might wn.ch Tes beWnd tbese, or with the warble of the nightingale, he caroUf the thrush, the lark's blithe lay, or the n.ocking- Wrd? n!.cm,^e, and the en.utional wealth which these ex- nress tne challenges and calls of love among jther classe ranimaL are apt'to seem lacking in force or beauty^ 1 u our human judgment affords no sure criterion. The f.ogs Td newts which lead on an average a somewhat sluggish Ufe wake up at pairing time, and croak according to .he,r strength The males'are often furnished with two rcsoiv at n/sacs at the back of the mouth, and how they can c k TeUersb; marsh-land know ; the North American bu frog bellows by himself, and the South American tree f.ogs ViniH a rnncert in the branches. '°'of the mJ^ing of fishes we know little, but there are ...ne well known cases alike of display and o tournament T stickleback fights with his rivals, leads h.s mate tc cH»p. VI The Domestic Life of Animals 99 the nest by captivating wiles, dances round lier in a frenzy, ■1! I^K' vj^K't '>! •i* !■ Fi'i . I.— Male and female bird of paradise {P.ir.uiiua minor). (From ICvolu tioH e/SiX ; after Catalogue of Dii.:,Jcn .Museum.) ■ind .ifterwurds guards the eggs with jealous care. The m ^m The Study of Animal Life PART I XOO male salmon, with their hooked lower jaws, fight with their rivals sometimes to the death. ,• i . i :i.^ 5S.t,ht sr :f *e,n are ™f .. u.„g «, Lrrl leas and wing-edges as mstruments. The crickets S mem"fth« LL "sing," and the death-watch tap. " t frslmer^lgh., when co.ours are put out by the darlne* the"tow.woL 'shines brightly on the mossy bank^ 7 r. Rritifh soecies (Ijvnpyr nccHlucct) the wingKl LV'»d the IgCfetiale Z. both luminous ; the latter ^^.M Mcels n brightness, while her mate has larger eyes. ^tv« Ae pho Jhorescence may mean to the const,tu.,o„ Srh^«ct!i^ is certainly a love-slgnal between the sexc . But U know most about the Italian glowworm (Luaoh, te to^ of whose behaviour we have a lively picture-tha„b « PmfessoT Emerys nocturnal observations u; the meadows .Li Moena The females sit among the grass i the Zl" s «y^Kn search of them. When a female catches Skh«s::.^-e^^rrg^;t;n:H S^rifn"ti::^irThV'^m:i^^^^^^^^^^^ coquette s ?»<"«• ' ij^„,.,jj ^nd the intensity seems ^mth th S;J t.^te >«« W the fem^e is .,we restricted The most noteworthy difference »s that tw Smrnous rhythm of the male is more rapid, with br,e^ flaThes while that of the female is more prolonged ith fonger inTervals, and more tremulous-iUummed symbols of J^'U. we did not ignore that the courtship o au«t mammals is somewhat rough So, ^«^J^J"'"f ,; ,^ dances of many butterflies, the merry songs of the tra ~'^m§^mK^mm*Js^:^sss^ 2] CHAP. VI The Domestic Life of Animals loi hoppers, and the flashing signals of the glow-insects, it is just that we should turn to the strange courtship of spiders, which is less ideal. Of what we may be prepared to find we get a hint from a common experience. Not long ago I found in a gorge some spiders which I had never seen before. Wishing to examine them at leisure, I captured a male and a female, and, having only one box, put them, with misgivings, together. When I came to examine them, however, the male was represented by shreds. Such unnatural conduct, though by no means universal among spiders, is common. The tender mercies of spiders are cruel. We have lately obtained an account of the courtship of spiders from George W. and Elizabeth G. Peckham, from whose careful observations I select the following illustrations : According to these observers, "there is no evidence that the male spiders possess greater vital activity ; on the contrary, it is the female that '<; the more ac*'ve and pugnacious of the two. There is no rel- . in either sex between development of colour and activity. 'Itie Lycosida, which are the most active of all spiders, have the least colour-development, while the sedentary orb- weavers show tlie most brilliant hues. In the numerous cases where the male differs from the female by brighter colours and ornamental appendages, these adornments are not only so placed as to be in full view of the female during courtship, but the atti- tudes and antics of the male spider at that time are actually such as to display them to the fullest extent possible. The fact that in the Altida the m.les vie with each other in making an elaborate dis- play, ^ only of their grace and agility, but also of their beauty, befor- t. females, and that the females, after attentively watching the dances and tournaments which have been executed for their Rraiification, select for their mates the males that they find most pleasing, points strongly to the conclusion that the great differences in colour and in ornament between these spiders are the result of sexual selection." These conclusions support Darwin's position that the female's choice is a great factor in evolving at'ractiveness, and are against Wallace's contention that bright colours express greater vitality, and that the females are less brilliant because enemies eliminate the conspicuous. It is quite likely that Darwin's view is true in some cases (e.g. these spiders), and Wallace's conclusion true in others (<^. birds and butterflies), m that both may be true in ^M^ ?:^Sft. i^^§ffMi i' *^ -i I02 Tlie Study of Animal Life PART I „„v c.^, »H.e ...fact ^^ tufS^l ^^ " '-\" Xays more brilliant than t^^l'X'l^y of maleness, which brSncy is wrapped «P^-lo"g ^ J ^^ superabundant vitality, or as it is not sufficient to ^f^^^f^i^^ey towards a relative increase greater activity, but rather as ^Jj^^^^^ges over those >.hich are ^f destructive or d.srupUve ^^'^^^ ^^^ Wem is very complex, constructive or ^^"^^f"^'':^' J't.^J^.^. We need to know and dogmatic conclusions are prcm . ^^ to winch . ?Je chemical nature and ^^^^°7,e ,n apprSmate balance-sheet colour is due ; we "--'^., ° ^^^JheU s'^xes. Knough of th.s, of the income and expenditure of the ^^^ ^^^^ romance- however ; let us return to the pictures. Su to these: patient observers: G W und E. G. Peckham.) e 1 tVint the males of Saiih .. On reaching the country we found that ^ .^ ^^^^ ^.^^ ;>„/.. were nuti.e and were waunjg f- hc^ej^ ^^^^ ,^ ,„niulc Cilh both spiders and msccts. In U^is i ^^ ^^^^^^^ ^ difference l^tween the sexes On May 4 ^^^ ^^^ ,, y female and placed her m one of Ojc larg« ^ ^^ ^,^^ ^^^^, ,,,1 we put a male m wuh her. He sa ^^ ^^^.^^ still, twelve =nches away. The glance .^^^^^^ f^,^„, ^et he at once moved toward her. ^^^^y^^J^^.^Uable performances he stood still, and then ^^^^^'^^ ^^dmnng female. She cyca that an amorous male <^°»l^;^^ "^^^^.r time to time, so that h him eagerly, changmg her f-'^ ^^^.;^\.„ ^.hde Ix^dy on one sj might always be '" -^^-j J'*^' J owering it on the other by foW- by straishtemng out th^ legs, aim CHAP. VI The Domestic Life of Animats 103 ing the first two pairs of legs up and under, leaned so far over as to be in danger of losing his balance, which he only maintained by sidling rapidly toward the lowered side. The palpus, too, on this side was turned back to correspond to the direction of the legs nearest it. He moved in a semicircle of about two inches, and then instantly reveised the position of the legs and circled in the opposite direction, gradually approachins; nearer and nearer to the female. Now she das'^es toward him, while he, raising his first pair of legs, extends them upward and forward as if to hold her off, but withal slowly retreats. Again and again he circles from side to side, she gazing toward him in a softer mood, evidently admiring the grace of his antics. This is repeated until we have counted one hundred and eleven circles made by the ardent little male. Now he approaches nearer and nearer, and when almost within reach whirls madly around and around her, she joining and whirling with him in a giddy maze. Again he falls back, and resumes his semi- circular motions with his body tilted over ; she, all excitement, lowers her head and raises her body, so that it is almost vertical. Both draw nearer, she moves slowly under him, he crawling over her head, and the mating is accomplished." The males are quarrel- some and fight with one another ; but after watching "hundreds of seemingly terrible battles " between the males of twelve differ- ent species, the obser- vers were forced to the conclusion that "they are all sham affairs gotten up for the pur- pose of displaying be fore the females, who commonly stand by in- terested spectators." "It seemed cruel sirait at first to put eight or ton males (of Dendiy- phaii/,s capitatiis) into abox to see them fight. Yxc, i — I'wo male spiders (Zygoballus btttini) fighting. (After O. W. and E. G. Peckh.im.) but it was soon apparent that they were very prudent little fellows, and were fully conscious that 'he who fii;hts and runs away will live t(. fight another d.ry.' In fact, after two weeks of hard fi hting we were unable to discover one wounded warrior. . . . The single female (of Phidippm morsitans) that we caught duung the 164 The Study of Animal Life PART I I FIG. .4.-Malc argus pheasant di>pbylng its plumage, tl'ron, l)arw»,.) rrs:«:s^Lr^r;.=":="°------^^ wmmm^^^^^%