CflCGY BRARY THE AQUARIUM; ITS INHABITANTS, STRUCTURE, AND MANAGEMENT. 1 THE AQUARIUM; ITS INHABITANTS, STRUCTURE, AND MANAGEMENT. BY J. E. TAYLOR, PH.D., F.L.S., F.G.S, ETC. AUTHOR OF 'HALF-HOURS IN THE GREEN LANES,' 'HALF-HOURS AT THE SEA-SIDE,' 'GEOLOGICAL STORIES,' ETC. LONDON : HARDWICKE & BOGUE, 192, PICCADILLY, W. 1876. .LONDON: PRINTED BY WILLIAM CLOWES AND SONS, STAMFORD STREET AND CHARING CROSS. TSM PREFACE. WE regard the institution of public aquaria as more or less the result of the deeper interest now felt in the life-histories of aquatic animals, consequent upon that extensive knowledge of natural history which is one of the intellectual features of our time. We believe their extension will be greater, on this account, than those people imagine who hold they will share the fate of "spelling bees," &c. That they are a popular means of education none will deny, and the success they have everywhere met with leads us to hope they are serving a good purpose. This little volume is intended as a handbook or popular manual to our public aquaria, so as to render them still more effective as a means of education. Their history, construction, and principles of manage- ment have been briefly described, as also the natural history of the chief animals which have been more or less successfully acclimatised. The list of the latter is constantly being extended, and there appears no JV1361857 vi PREFACE. limit to the number which may be healthily main- tained and exhibited. We have had the great advantage of having the following pages overlooked by Mr. W. A. Lloyd, of the Crystal Palace, to whom our best thanks are due for many valuable suggestions. The work is now presented to the public in the hope that it may add to the educational effects of our public aquaria, and be the means of rendering the education in zoology more popular and exten- sive. IPSWICH, September 21, 1876. CONTENTS. CHAPTER I. THE HISTORY OF AQUARIA. Works of P. H. Gosse — The ' Origin of Species ' — Fish sup- plies — Royal Comniission on Fisheries — Ova of cod and whiting, how deposited — Discovery in Brighton Aquarium — Saville-Kent on history of common herring — Dr. Gunther on " whitebait " — Professor Sars on cod ova — Mr. Lloyd on herring culture — Herring in Manchester Aquarium — Young of crawfish (Phyllosomd) — Hamburg Aquarium — Growth of salmon — Mr. Jackson on salmon-trout — Ancient fish- ponds — Roman piscina — Red mullet — Cost of Roman fish- ponds — Chinese fish-culture — Mediaeval fish-culture — An- tiquity of the pike — Fish-food of the thirteenth century — The edible frog — The common frog — The life-scheme of our globe Page i CHAPTER II. HISTORY OF AQUARIA — continued. Priestley's discovery of oxygen — Trembley and his Hydras — Sir John Dalyell — The Bordeaux Aquarium — Dr. Daubeny on plants and animals — Dr. N. B. Ward's experiments on aquaria — Dr. Johnston's zoophytes — Mrs. Anna Thynne — Mr. R. Warington's experiments on aquaria — Mr. Gosse's ditto — Works of Mr. Gosse — Aquaria at Surrey Zoological Gardens and Dublin ditto — Dr. Ball's contrivance for viii CONTENTS. aeration — Mr. Gosse's artificial sea-salts — Hanover and Berlin Aquaria — Aquaria in British and continental towns — Havre Aquarium — Aquarium of the French Acclimatisa- tion Society — Naturalists at British aquaria — The Crystal Palace Aquarium — History and structure of ditto — Ditto of Brighton Aquarium — Dr. Dohrn's aquarium at Naples — Professor ..Agassiz's aquarium at Penekese Island — The Manchester Aquarium' — Southport ditto — Yarmouth ditto — Westminster ditto — Aquaria in course of erection Page 10 CHAPTER III. PRINCIPLES OF THE AQUARIUM. Pleasures and educational influence of aquarium keeping — Cruelty to animals — Streamless aquaria — Relation of animal to vegetable life — Balance of ditto — Parasitic fungi on aquarium animals — Lloyd's contributions to literature of aquaria — Over-stocking aquaria — How to proceed in stocking an aquarium — Bell-glasses and their uses — De- velopment of green algae in aquaria — How to arrest ditto — How to keep down ditto — Temperature of ditto — Water in aquaria not to be changed — • Aquarium fountain — Aquatic plants — Structure of cheap fountain — Evaporation of water in aquaria — Dust in ditto — How to remove it • • • • 24 CHAPTER IV. CONSTRUCTION OF FRESH-WATER AQUARIA. Where materials can be purchased — Details of cheap aquarium — Bell-glasses — Dr. Lankester's ' Aquavivarium ' — Flower- stand with bell-glass aquarium — Oblong tank for window aquaria — Polygonal tanks — Cement for joining sides of tanks — Rockwork of tanks — Materials for rockwork — Fresh-water plants for tanks — Duckweeds — Mud and sand for fresh-water aquaria — Deddorisation of aquaria — How to prepare aquatic plants for aquaria — Stock animals for CONTENTS. . ix ditto — How to remove decaying objects from ditto — How to feed aquatic animals — Best food for ditto — How aquaria get wrong — Means of putting aquaria right — " Conva- lescent " glass — Best plants for ditto — Circulating fresh- water aquaria — How to keep aquaria perpetually healthy Page 36 CHAPTER V. AMPHIBIANS AND FISHES OF THE FRESH-WATER AQUARIUM. Over-stocking aquaria — Yellow-spotted salamanders — Mexican Axolotl — Great water newt — Superstitions regarding ditto — Male and female of ditto — Smooth newt — Habits of ditto — Habits of great warty newt — Tadpoles of smooth newt — Development of ditto — Food of ditto — Straight- lipped warty newt — Palmated smooth newt — Spawn of frogs and toads — Goldfishes and their food — Three-spined sticklebacks — Nest-building habits of ditto — Rough-tailed stickleback — Miller's thumb — The loach — Food of loach and gudgeon — The minnow — The " pope " — Common perch — Common and Prussian carp — The bleak — Scales of ditto — Roach and dace — The "rudd"— The pike — Dr. Lankester on ditto — Silurus glanis — Introduction of ditto in English rivers — Ganoid fishes — The bony pike — Acclimatisation of foreign fishes 50 CHAPTER VI. THE AQUATIC GARDEN AND ITS PLANTS. Circulatory system of aerating large aquaria — Mr. Kent on fungoid growth upon fishes — Probable cause of ditto — Selection of aquatic plants for ornamental purposes — The mare's tail — Canadian weed (Anacharis) — Vallisneria — Flowers of ditto — Water lilies — Water plantain — Arrow- head — Flowering rush — Forget-me-not — Water mint — x CONTENTS. Brook lime — Water violet — Speedwell — Buck-bean — Flowers of ditto — Aquatic Polygonum — Water crowfoot — Dimorphous leaves of ditto — Water frog-bit — Water soldier — 'Abundance of ditto in eastern counties — Bladder- wort — Leaves of ditto — Villarsia and Trapa — Pond weeds — Star- worts — Horn- wort — Water milfoil — Sweet flag — Bur-reed — Beauty of aquatic gardens • • Page 7 1 CHAPTER VII. MOLLLUSCA, INSECTS, ETC., OF THE FRESH-WATER AQUARIUM. Bryant's " Thanatopsis " — Stock of aquaria — Battles in ditto — Mollusca of ditto — Limnea stagnalis — L. auricularia — Habits of these two species — Limnea pereger — Planorbis corneus — Geological antiquity of fresh-water shells — Plan- dina vivipara — Habits of ditto — Bythnia, Pisidium, and Sphcerium — Use of ditto in aquaria — Swan mussel — Unios — Aquatic insects — Life-histories of ditto — Metamorphoses of ditto — Dragon-flies, larvae of — Larva of Dyticus — Fero- cious character of ditto — Dyticus marginalis, male and female — Habits of ditto — Great aquatic beetle (Hydro- philus) ; its habits — Wriggling beetles — Water bugs — Water scorpions — Water boatmen — Various species of caddis-worms — Development of ditto — Larvae of Ephemerce — Water spiders and ticks — Nest of water spider — Care required in selection of aquatic insects, &c. 97 CHAPTER VIII. THE AQUARIUM AS A NURSERY FOR THE MICROSCOPE. Interest of aquarium objects — Microscopic life — Desmids and diatoms — Unicellular character of ditto — Hyalotheca, Euastrum, Cosmarium, Closterium, and other desmids — Nature and habits of desmids — Structure of desmids and diatoms — Frustules of diatoms — Their siliceous character CONTENTS. xi — How to prepare them for microscopical mounting — Beauty of diatom frustules — Utilisation of ditto in the arts — Various species of diatoms, Isthmia. Pinnularia, Pleuro- sigma, Navicula, Stauroneis, Cocconeis, &c. — Stalked diatoms, as Licomophora — Structure of latter — The Amoebas — Fresh-water sponges — Structure of ditto — Hydras — Their habits and development — Rotifers — Sessile rotifers — Melicerta and Stephanoceros — Their habits and structure — Infusoria — Vorticella, Epistylis, &c. — Rotifer vulgaris — Habits of ditto — Fresh- water polyzoa — Lophopus crystalling Plumatella repens, &c. — Cyclops, its habits and development — Water fleas — Relation of animalcules to each other Page 113 CHAPTER IX. MARINE AQUARIA FOR ROOMS. Difficulties attending private marine aquaria — Construction of ditto — Rockwork for ditto — Polygonal marine table tanks — Sea-weeds for ditto — Sea-lettuce (Ulvd) — Cladophora — Oxygen-yielding qualities of certain sea-weeds — Calli- thamnion — Green and red sea-weeds — Delesseria and Plocamium — Cladophora, Bryopsis, Griffithsia, Ceramium, Rhodymenia, Padina, Corallina officinalis, &c. — Small wrack — " Irish moss " — Fructification of sea-weeds — Zoo- spores of ditto — Their use as food for lowly organised animals — Best time for introducing sea- weeds into aquaria — Spontaneous appearance of sea- weeds in tanks of public aquaria — Oxygenation of sea water — Artificial oxygen — Marine scavengers, as Haliotis, Patella, &c. — Mr. W. R. Hughes on construction of marine tanks — Dark-chambered slope-backed tanks — Aeration of tanks — Contrivances for ditto — Regulation of light and temperature of ditto — Evaporation of water — Artificial sea-salts, their chemical composition — Mr. Gosse on ditto — Specific gravity balls and hydrometers — Self-acting air-can for preserving aquatic animals 139 xii CONTENTS. CHAPTER X. OUR PUBLIC AQUARIA. Establishment of large public aquaria — Mr. Lloyd's part in developing ditto — The Crystal Palace Aquarium — Ditto at London and Dublin Zoological Gardens — Show tanks in public aquaria — Circulation and aeration of sea water in ditto — Barnum's white whales — Hurwood's contrivance for aerating large aquaria — Application of ditto in Hamburg Aquarium — Mr. Lloyd's method of large underground reservoirs — Saville-Kent on ditto — Crystal Palace and Brighton methods of circulation in aquaria — Relative merits of ditto — Capacity of tanks in Crystal Palace, West- minster, Brighton, Great Yarmouth, Manchester, and South- port Aquaria — Details of sizes of tanks, &c., in ditto — Food-tanks of our public aquaria — Cost of food for animals in ditto — Food of animals in ditto — Nocturnal habits of herrings and dog-fishes — Saville-Kent on ditto — How marine animals are fed — Organic matter in sea water Page 161 CHAPTER XI. MAMMALIA, REPTILIA, AND FISHES OF PUBLIC MARINE AQUARIA. Lung-breathing aquatic animals — Grampuses at Brighton Aquarium — Porpoises at ditto — " Sea-lions " at ditto — Alligators and crocodiles at Southport, Manchester, and Brighton — Edible turtles at Brighton — Hawk's-bill turtle — Marine fishes — The lancelet (Amphioxus) at Sydenham — Mud-fish at Brighton — Smooth hound and tope — Common dog-fish — Its habits — Small-spotted dog-fish — Eggs of skate and dog-fish — Mode of reproduction in sharks and rays — Thornback — Angel fish — Homelyn ray — Common skate — Sharp-nosed ray — Cat-fish — Teeth of CONTENTS. xin ditto — Smooth blenny — Secretions of fishes — Parasites of ditto — Beauty of the blennies — Butterfly blenny — Vivi- parous blenny — Young of ditto — Tameness of the blennies — Rock goby — Structure of sucking disk of ditto — Spotted goby — Heterogeneous character of " whitebait." Page 175 CHAPTER XII. FISHES FOR MARINE AQUARIA. Attractive marine fishes — The wrasses — Ballan wrasse — Structure of mouth of wrasses — Male and female wrasses — Their difference in colour — Habits of wrasses — Red wrasse — Food of wrasses — Young of wrasse — Cuckoo wrasse — Corkwing and rainbow wrasses — The dragonet — Difference between male and female of ditto — Angler fish — Modi- fication of dorsal fin-rays of ditto — Lump sucker — Struc- ture of sucking disk — Young of lump sucker — Fifteen- spined stickleback — The pogge — The ' gurnards, their colours — Butterfly gurnards — Modification of rays of pec- toral fins of gurnards — Streaked gurnard — Grey gurnard — The piper — Lesser weever — Sting rays of weevers — Dr. Gunther on ditto — The basse 192 CHAPTER XIII. FISHES FOR THE MARINE AQUARIUM. Migratory fishes in aquaria — Mackerel in Brighton Aquarium — Herrings in ditto — The pilchard — Whiting and cod — Ova of cod — Spawning of cod at Brighton and Sydenham — Food of cod — Three-bearded Rockling — Five-bearded ditto — Haddock — Coal-fish — Grey mullet — Food of ditto — Sea-bream — The sturgeon and sterlet — Pipe-fishes, their habits and structures — Different species of pipefishes — Breeding of ditto — Sea-horses (Hippocampi} — Their struc- ture, habits, and food — Breeding of ditto at Manchester and Southport — Flat-fishes — Their embryology — Adaptation xiv CONTENTS. of colour to sea-bed — Structural modifications of flat-fishes — The plaice, sole, and turbot — Difference in coloured sides of ditto — Modification of eyes of ditto — The brill, dab, halibut, turbot, &c. — Conger-eel, John dory, and guard fish — Mud-fishes — Modern study of fish • • Page 209 CHAPTER XIV. CUTTLE-FISH, MOLLUSCA, ETC., OF MARINE AQUARIA. Victor Hugo's octopus — Mr. Henry Lee on the octopus — Huge octopuses or cuttle-fish — Fishermen's stories of ditto — The common octopus — Structure of ditto — Habits and food of ditto — Common sepia — Internal bone of ditto — Its micro- scopical structure — Common squid — Pen of ditto — Welsh octopus — Geological antiquity of cuttle-fishes — Mollusca for shallow water-tanks — Limpets, chitons, &c. — Structure of chitons — Young of ditto — Key-hole limpet — White whelk — Egg-cases of ditto — Red whelk — Venus' ear, or Haliotis — Nassa and Purpura — Vegetable scavengers — Natica, Turitella, and Trochus — Shell-less mollusca or sea- slugs — Aplysia, Doris, &c. — Bivalve mollusca — Their re- productive powers — The common mussel — Oysters — Their usefulness in aquaria — Young of ditto — Food of ditto — Life-history of oysters — American clams — Species of cockles — Pectens or scallops — Boring mollusca — Sand mussels — Wood-boring mollusca — Mactras, Tellinas, Lima, Cyprina, &c. — Ascidians — Young of ditto — Sea- mats — Structure of ditto — Botryllus — Clavelina, &c. 228 CHAPTER XV. CRUSTACEA, ECHINODERMS, ANNELIDS, ETC., OF MARINE AQUARIA. Animals as aquarium scavengers — Hermit crabs — Habits and structure of ditto — Battles of ditto for empty shells — Spiny lobster, or crawfish — Embryology of ditto — CONTENTS. xv Common lobster — Embryology of ditto — Life-history of lobster — Mr. Lloyd on moulting of lobster — Prawns — Common shrimp — Habits of shrimps — Banded shrimp — " Cup shrimp " — Gammarus and Hippolyte — " Night- walker" — Squat lobsters — Shore crab and edible crab — Spiny spider-crab — Mr. Lloyd on decoration of certain crabs — Miss G. Stephens on ditto — Hyas, Pisa, Inachus, £c. — Swimming crabs — Crabs at Sydenham — Masked crabs — Northern stone-crab — Nut crabs, &c. — Barnacles — Life-history of ditto — Various species of ditto — Barnacles at Sydenham — Lepas and Scalpellum — Star-fishes and sea-urchins, their structures — Ambulatory apparatus of ditto — Habits of ditto — Ur aster, Ophiura, Ophiocoma, Solaster, Comatula, &c. — Sea-cucumbers — Annelids or sea worms — Various species of ditto — Sea-mouse — Habits of sea worms Page 254 CHAPTER XVI. SEA- ANEMONES AND OTHER ZOOPHYTES, ETC., OF MARINE AQUARIA. Gosse and Lankester on sea-anemones — Couch's story of sea- anemone — The dahlia wartlet — Plumose anemone — Diet of sea- anemones — Orange-disked anemone — Daisy anemone — Cave-anemone — Parasitical anemones, Adamsia, &c. — Messmateship of Adamsia and hermit crabs — Beadlet anemone — The opelet — Corals in aquaria — Caryophyllia, Balanophyllia, &c. — Gorgonias or sea-fans — Iris, Hippuris, &c. — Structure of Gorgonias — Campanu- larians — Larvae of ditto — Oaten-pipe corallines — Sea-firs, or Sertularia — Hydra-tuba — British sponges in marine aquaria — Various species of sponges — The marine aquarium as a nursery for microscopic animals — Conclusion • • 289 INDEX 311 THE AQUARIUM. CHAPTER I. THE HISTORY OF AQUARIA. NOTWITHSTANDING a good deal of quibbling which has taken place respecting the word "Aquarium," there can be no doubt it has now gained its ground, as signifying contrivances for the support of living fresh-water and marine animals under such artificial conditions as resemble their natural surroundings. The word has passed out of the region of philology into that of common parlance, and has now become stereotyped in dictionaries. The charming works of P. H. Gosse undoubtedly did much to make aquarium keeping popular about twenty-three years ago. Everyone who loved nature could not help feeling attracted towards the lovely objects, which he showed were so abundant on our coast, after his animated descriptions of them. To a great extent this was in advance of the natural science of the time, and although it was the means If B 2 THE HISTORY OF AQUARIA. of collecting a great deal of information relative to the habits of the invertebrate animals, it had to fall back until science came up with it. The enormous strides which natural science has made since the pub- lication of the ' Origin of Species ' have necessitated large aquaria, where the new study of the embryology and larval conditions of the lower animals could be more easily followed. Since that time, also, zoology has become more attractive even to general readers. The fact that evolutionists and non-evolutionists have taken sides over zoological questions, renders it im- perative that both shall observe more and theorise less. It has been found, also, that large aquaria may be rendered places of the highest amusement, as well as of the easiest and pleasantest instruction. Hence their numbers are largely increasing, and we doubt not the time is not far distant when all our large towns will be provided with them, so that all classes may know more of the marvellous works of God. To economists, aquaria cannot fail to be of the highest interest, for even within the last few years, observation at several of them has settled various most important facts relating to the life-history of some of those creatures which are most valuable to us as food. In one instance, at least, it was the means of preventing the framing of a law that was based on zoological ignorance, and which would have done as much harm to our fish supply as it was intended to do good ! In 1865 a Royal Commission, on which OVA OF CODFISH. 3 several naturalists sat, met at some of our fishing ports, and took evidence from fishermen and others as to whether trawling did not do much harm, by breaking up the sea bed where the ova of fish had been deposited. The idea then was that the cod and whiting — two of the most abundant of our native food-fishes — deposited their eggs on the sea floor. Professor Sars, the well-known Danish naturalist, had expressed his opinion that the ova of these fish floated on the surface ; but it was first substantiated in the Brighton Aquarium, where it was found that the ova both of these fish and the mackerel, floated on the surface during the entire period of their development. Had it not been for this discovery, it is more than likely that by this time the fishing trade, as well as the fish supply, would have been crippled by a law which would have restrained trawling operations over cod grounds during the whole of the spawning season. Mr. Saville-Kent, at the Manchester Aquarium, has contributed towards the history of the common herring, from its young state. Dr. Gunther, the well- known ichthyologist, had already declared his belief that by far the greater part of " whitebait" consisted of the fry of herrings.* If this is so, then, in con- suming them so recklessly, we are interfering with the chief fish-food of the common people. . Mr. Lloyd * Dr. Gunther affirmed that Clupea alba, or whitebait, was the young of Clupea harengus, or the common herring. B 2 4 THE HISTORY OF AQUARIA. (who was the first to keep whitebait in London, in 1858), and others had experienced a difficulty in herring culture. In consequence of the migratory habits of these fish they often injured themselves by dashing against the glass or the rockwork of the tank in which they were kept. As they move about principally by night, it struck Mr. Kent to illuminate the tank by a feeble light, so that the outlines of the walls, rocks, &c., should be visible to the fish. This plan succeeded admirably, and by its aid Mr. Kent kept and fed whitebait until they have grown to half the size of the ordinary herring. At the time he made this announcement, the fish were eighteen months old.* In addition to the above-mentioned important facts with which our large aquaria have made us ac- quainted, there are others not yet worked out, but which are in process of careful observation. It was discovered in the Hamburg Aquarium that the Phyl- losoma, one of the " glass crabs," which had been placed in a separate order prepared for it, is only the young of the crawfish (Palinurus quadricornis). The Brighton Aquarium has further contributed impor- tant information as to the rapidity of the growth of the salmon. Before then, the growth of this fish was thought to be much slower than observation and ex- * Mr. Kent obtained his specimens in a very young state. The only person who has hatched out herrings in aquaria is Mr. Stephenson, of Brixton. : RED MULLET. 5 periment have proved. At the Southport Aquarium, under Mr. C. L. Jackson, experiments are being con- ducted which will make us better acquainted with the life-history of another valuable food-fish, the salmon- trout. Although artificial contrivances for preserving fish alive have undoubtedly been in vogue for many centuries, aquaria, in the sense in which we under- stand the word, are peculiarly modern. The ancient Romans paid as great attention to their fish-ponds as wealthy gentlemen, of horticultural tastes, now do to their orchid and fern houses. No expense seems to have been spared in making these fish-ponds as large and attractive as possible, or in obtaining valuable and beautiful fish for stocking them. Amongst others, the red mullet (Mullus barbatus ?) appears to have been the greatest favourite. It was kept in the ponds for the sake of its beauty, and was usually brought to the table alive, so that the assembled guests could indulge in the pleasure of witnessing the rapidly changing prismatic tints which the fish assumed whilst dying. Not unfrequently canals led from the fish-ponds into the banqueting hall. The red mullet, when it attained a large size, was of great value ; one of four pounds and a half fetching a sum equal to 6o/. sterling. These mullets are immortalised by the price that was given for them in the reign of Caligula, about 24O/. Pliny relates that the fish-pond of one of the Roman patri- cians (C. Herius) was sold for a sum amounting 6 THE HISTORY OF AQUARIA. to more than 32,ooo/. So extensive were these ponds, and so well stocked, that the same gossipy naturalist tells us the fish alone from the ponds of Lucullus, the well-known gourmand, fetched a sum as large as that just named ! The Romans were capital judges of another modern delicacy, the oyster, the modern demand for which has been run almost as high as it was nearly two thousand years ago. Reser- voirs were constructed for the preservation of oysters, and large sums of money were laid out in getting stock and taking proper care of them. The Chinese have long kept live fish for the table and market. Our well-known gold and silver fish (Cyprinus auratus) come from their country, and were introduced into Europe as ornamental living objects more than two centuries ago. Pepys perhaps refers to these in his ' Diary,' as a " fine rarity ; of fishes .kept in a glass of water, that will live so for ever — and finely marked they are, being foreign." Both the Japanese and Chinese have long kept these fish in artificial tanks and glasses for amusement, and have succeeded in roughly training them. During the middle ages, fish-ponds were esteemed a necessary appurtenance to monasteries, abbeys, and even halls. The long abstinence from all animal food, except fish, during Lent, and the many other fasting days imposed by the Church, rendered it necessary that fish of some sort should be easily available for use. The moats which ran round castles or other baronial buildings, ANTIQUITY OF PIKE. 7 often served the double purpose of defence and fish preserves. In the immediate neighbourhood of abbeys we usually find large fish-ponds, unless (as is frequently the case) these religious buildings stood near some well-known stream. No doubt at this time, in spite of the difficulty of transit, European fish were more or less interchanged, so that it does not do to accept their present geographical distribution as a natural one. It is all but certain that the carp was brought from southern Europe to the more northerly parts ; its great size and esteemed flavour rendering it a favourite. The pike is said to have been introduced into England in like manner, but this is hardly likely, as we find its remains in the post-glacial river-bed of Mundesley, in Norfolk. Thus we have incontestable evidence of the existence in Britain of the pike long before the historic period, and when the physical geography of the surface was, in Norfolk at least, very different from what it is now. Tastes, as regards fish and other aquatic animals, have differed much since mediaeval times. The upper classes regarded pike and tench as fit only for the lower orders, whilst they did not scruple to enjoy the coarse flesh of the sea dog, the porpoise, and even the whale ! In an old document of the thirteenth century, about fifty kinds of fish are mentioned which were retailed in the French markets. Lacroix says that a century later, the flesh of the whale was salted down for the use of the common people. Congers, 8 THE HISTORY OF AQUARIA. cuttle-fish, and sturgeon were the principal food-fishes of the masses ; whilst turbot, sole, and " John Dory " had even then obtained, by their high price, the aristocratic position of catering only for the stomachs of the wealthy. The edible frog (Rana esculentd) is another animal which has been specially cared for by those who have learned to like it as an article of food. Tanks or ponds, in which it can pass through its ordi- nary life-history, and whence it can easily be fished out for the table, still exist in France. Of course we need not here do more than remark that the edible frog is another species than that which is so common in England ; although there is no reason in the world why the latter should not be as dainty an article of food, if there were only more of it. Pond frogs were regarded as among their choicest morsels by the ancient Gauls and Franks, in whose country these amphibians have continued to be more or less favourites ever since. Formerly they were served at the best tables, dressed with a green sauce. Between the artificial contrivances for the preser- vation of aquatic and other animals designed for the table, and the modern aquaria in which they are kept to administer to the growing love for knowledge, there is as great a gulf fixed as there is between the mind and the stomach. Very little knowledge indeed has been handed down to us from the costly piscinae of the ancient Romans, or the more homely fish- EDIBLE FROG. 9 ponds of mediaeval times. From the lofty eminence whence ignorant men looked down, all lowlier creatures seemed beneath their study. It remained for the era when we had learned to regard all things that God has made as worthy of our consideration, to increase our knowledge of their " times and seasons." We can hardly imagine it possible that little more than a century ago the " great Cham " of English literature declared that natural history was a study only fit for children ! And we are thankful that we have grown to this — to regard the great life-scheme of our planet, past and present, including objects as minute as others are huge, and as structurally simple as others are complex, as one in its nature, evolved through the omniscience of an All-wise Being ! If nothing less than Omnipotence could have produced it, surely we cannot but esteem it one of the noblest studies in which the human mind can be engaged. Science is one with the Psalmist in regarding the inorganic and organic kingdoms of nature as doing His will — beasts and all cattle, worms and feathered fowls, mountains and hills, fruitful trees and all cedars, fire and hail, snow and vapour and stormy wind fulfil His word ! 10 THE HISTORY OF AQUARIA, CHAPTER II. THE HISTORY OF AQUARIA — COntimied. THE most natural of all the artificial conditions under which fish were kept in readiness for the table were the old fish-ponds. Many of the latter were covered with the usual aquatic vegetation, which thus kept the water pure ; or else a stream regularly passed through the lattice-work at either end. The relation which plants and animals bear to each other was not fully known even half a centuiy ago. It required con- siderable progress in chemistry before the gases which they gave off were understood. Unquestionably the first step in this direction was made by Dr. Priestley, of Birmingham, who observed that oxygen gas was given off by plants when under the active stimulancy of sunlight. Aquatic animals had been described by Trembley, Baker, Leuwenhoek, Hooke, and others ; but they either obtained them direct, or else, as Trembley did his Hydras, kept them in jars by constantly changing the water. Naturalists were not aware of the needlessness of their labour until a long period afterwards. Even Sir John Dalyell, whose minute investigations into the structures and habits of zoophytes were published in his splendidly illustrated ORIGINAL A Q UARIA. 1 1 work on 'The Powers of the Creator displayed in the Creation/ and in his ' Rare and Remarkable Animals of Scotland,' and who kept many of the animals alive whilst he was observing on or experi- menting with them, did so by constantly changing the sea water in which they were kept. One of the most wonderful things in a modern aquarium, to a person ignorant of natural history, is that the sea and fresh water never want changing. Such people have not yet learned that the dry land of the entire globe is only one huge vivarium, and that the Atlantic and Pacific oceans, as well as all rivers and lakes, are likewise only immense natural aquaria. This well- being of terrestial and aquatic plants and animals is kept up and perpetuated without changing either the air or water. What naturalists strive after is, to re- present these natural conditions as much as possible. One of the first notices we have of the establish- ment of aquaria on the modern basis of adjusting animal and vegetable life, is that of Bordeaux, com- menced by M. de Moulins, in 1830. This naturalist found that by keeping plants in the water where his fish and mollusca were, the latter were stronger and healthier for it. But the question shortly afterwards assumed a thoroughly scientific foundation, although the cautious way in which conclusions which now seem to us self-evident, were approached, may appear ludicrous. They were accepted, however, in the true spirit of scientific research, which ought not to take 1 2 THE HIS TOR Y OF A Q UARIA . anything for granted that has not been amply proved. At the meeting of the British Association at Cam- bridge, in 1833, Dr. Daubeny showed that plants ' when in water (and aquatic species particularly) gave out oxygen and absorbed carbon under the influence of light. After detailing his experiments he expressed his opinion — an opinion which has since then not only been proved true, but which is universally accepted — that " he saw no reason to doubt that the influence of the vegetable might serve as a complete compensation for that of the animal kingdom." An old proverb says : "A child on a giant's shoulders sees farther than the giant." It is only the superficial who smile at the strenuous efforts of great intellects to attain unto a knowledge of those principles which we now regard as self-evident and incapable of contradiction. There is an evolution of knowledge as there is of animal and vegetable life. Daubeny saw dimly less than half a century ago what every teacher in physical geography now imparts to his class — that the oxygen generated in the virgin forests of the Amazons valley may be brought by the wind to bring health to the fetid streets and alleys of crowded European cities, and that in return the carbonic acid breathed forth from our over-populated towns may be carried on the " wings of the wind," to be eventually absorbed by the incalculable stomata which crowd the under surfaces of the leaves in the same forest-clad region ! o The labours of an unassuming but true naturalist, JOHNSTON'S EXPERIMENTS. 13 Dr. N. B. Ward, did much towards proving to students of nature that the magnificent views of Priestley, Daubeny, and others were both true and capable of being practically applied. Mr. Ward, in 1842, pub- lished a little work which gave a series of experiments showing that animals and plants might be kept in air- tight glass cases, and that each might be so adjusted as to breathe in what the other breathed out. He had commenced this study in 1837, and the celebrated " Wardian cases " for 'ferns, now to be seen in most drawing rooms, are the popular results. Dr. John- ston, the well-known writer on ' British Zoophytes,' adopted the above-mentioned compensatory principle in 1842, at which time he had a store of sponges, zoophytes, &c., in course of artificial preservation for scientific purposes. These animals were kept in small vessels wherein had been placed the common Coral- Una, the sea lettuce (Ulva), and several others; and the result was so successful that he suggested the possibility of marine aquaria on a more extended scale.* The knowledge thus gained by a few experiments was destined shortly to receive considerable accre- tions. In 1850, Mr. R. Warington (whose name is inseparably associated with the history of aquaria) made a communication to the Chemical Society on * The first attempt to keep the sea water constantly fresh by the presence of living seaweeds was successfully carried out by Mrs. Anna Thynne, in 1846. 14 THE HISTORY OF AQUARIA. his own experience in keeping a fresh-water aqua- rium. It was of a very simple and unpretending character, and differed little from that to which Pepys refers in his ' Diary/ consisting merely of a glass globe of fresh water in which two goldfishes had been placed, together with some plants of Valisneria. The latter is one of the best oxygen-producers of all known aquatic plants, and has long been a favourite with aquarium keepers. By-and-by, Mr. Warington introduced some pond snails to eat away the green algae which formed along the inner surface of the glass. Two years afterwards, he and Mr. Gosse ex- perimented after a similar fashion with sea water. This was the commencement of that rage for small marine aquaria which shortly afterwards set in. Tanks were constructed for the purpose, and marine animals and plants introduced in such proportions as were hoped to neutralise each other's respiration. The most marked epoch in the history of the marine aquarium, however, undoubtedly took place when Mr. Philip Henry Gosse's most charming books made their appearance. Their attractive style of description of the lovely objects which are to be found in the commonest rock-pools of our coasts, and which it is possible to preserve to constantly delight the eye, induced hundreds of people to com- mence aquarium keeping. Never before had the common objects of the seaside found a historian at once so charming and so accurate. And although, GOSS£'S EXPERIMENTS. 1 5 after a time, a great many people took to some other new " hobby," and allowed their aquaria to fall into neglect, sufficient enthusiasm was created to keep up the practice to the present time. Some of our public museums, notably that of Liverpool, shortly after- wards exhibited small tanks or glass vessels, con- taining aquatic animals and plants so arranged as to keep up an equilibrium. Mr. Gosse first began with sea anemones, the easiest of all marine objects to obtain and afterwards to keep in healthy order. A collection of these, and of some scarcely less attractive sea worms which he had -made at Ilfracombe, were purchased by the Zoological Society of London, and transferred to the new fish-house which had just been built in the Zoological Gardens. In making a further collection for the aquarium which was opened there in 1853, Mr. Gosse gathered most of the material that shortly afterwards appeared in his work on the ' Ma- rine Aquarium ' and ' Rambles of a Naturalist on the Devonshire Coasts.' The small aquarium opened in the Zoological Gardens, London, in 1853, was the first public one started in England, and, although it has long been superseded, it has done good work. In the same year another public aquarium was opened for a short time at the Surrey Zoological Gardens. That at Dublin, which commenced about the same time, was more long-lived, and was remarkable for the ingenious way in which the curator, Dr. Ball, supplied the tanks with fresh air. He so constructed air-bellows that 16 THE HISTORY OF AQUARIA. the visitors to the aquarium worked them with their hands, as a sort of amusement in the intervals of pacing about examining the tanks, and the Doctor found the air supply thus administered was sufficient. It is, however, too uncertain a method for other institutions to copy. - In fitting up small marine aquaria, the chief difficulty which people found who lived inland was in getting good sea-water. To meet this want, in 1854, Mr. Gosse showed how artificial sea-water could be manufactured, by simply adding salts to pure fresh water. The now largely used artificial sea-baths are produced by a small modification of Mr. Gosse's recipe. So successful was the experiment that even great public marine aquaria, like those soon after- wards founded at Hanover and Berlin, were supplied with salt water manufactured after Gosse's fashion. As soon as it was found that no great labour was needed to keep marine and fresh-water animals alive and healthy, in simply aerating the water, or in having properly adjusted aquatic plants, public aquaria were commenced in many of the large towns in Europe. Although these were not of the pretentious character with which we have now learned to associate the name, they did much to develop an interest in na- tural history. Before long there were aquaria at Belfast, Galway, Edinburgh, Scarborough, Weymouth, Boston, Vienna, Hamburg, Cologne, and especially at Havre. Some of them consisted of only one huge FOREIGN AQUARIA. 1 7 tank, wherein the animals obtained fresh air either by pumping it in, or by the natural aeration of plants. If the tanks were large, however, it was found that the latter system was attended with a good deal of difficulty. Hence the large tanks were usually aerated by causing the water to circulate and be injected in sprays, or else jets of air were forced into the water, which thus came into contact with oxygen, at the same time giving up its carbonic acid. The interior of the large tank in the Havre Aquarium was fitted up with rockwork, so as to resemble Fingal's Cave, in Staffa. Similar devices, all of them in bad taste, have been adopted at the Brussels, Hanover, Boulogne, Berlin, and Cologne aquaria. The first of those large public aquaria, which have lately grown to such colossal proportions, was that opened by the French Acclimatisation Society, in the Bois de Boulogne, in 1861. Its length is 150 feet, and it is fitted up with fourteen tanks, each of which contains two hundred gallons of water. Ten tanks are devoted to fresh- water objects, and four to marine. The aquarium at Hamburg, opened in 1864, has also been very successful. It has long been considered one of the best on the Continent ; much of its success depending upon the fact that Mr. William A. Lloyd was the deviser, and for some time the curator. Under his able management the zoological department attracted a good deal of attention among naturalists. In Great Britain we have hitherto been C 18 THE HISTORY OF AQUARIA. very fortunate in having men who are well known as naturalists at the head of our large aquaria. Thus Mr. Henry Lee has charge of that at Brighton. Mr. W. Saville-Kent was for some time curator of the Manchester Aquarium ; afterwards he partly super- intended the erection of one at Yarmouth, and now he is consulting naturalist to the extensive aquarium recently built at Westminster. Mr. W. A. Lloyd has had charge of the well-known Crystal Palace Aquarium since its opening in 1871 ; whilst at South- port there is a careful and diligent naturalist super- intending the aquarium in Mr. C. L. Jackson. We may regard the establishment of the Crystal Palace Aquarium as an important epoch in the history of the great public aquaria in this country. Its success undoubtedly stimulated that at Brighton into exist- ence, and the fact that the latter paid a good dividend (always an important one to Englishmen) was quite sufficient to induce companies to start those at Man- chester, Southport, Yarmouth, and elsewhere. The size of the Crystal Palace Aquarium is 400 feet long by 70 feet broad, whilst the frontage of the tanks amounts to 390 feet. There are sixty large tanks exhibited, besides those held as reserve. These con- tain 20,000 gallons of sea water, whilst there is a large storage reservoir which holds 100,000 gallons more. The largest of these tanks is 20 feet in length, and holds 4000 gallons of sea water. The animals within the large tanks are viewed through the glass THE BRIGHTON A Q UARIUM. 1 9 fronts. There are two adjacent rooms, however, in which stand twenty other tanks, varying in capacity from 40 to 270 gallons, where the animals are viewed from above, looking down into the water, as well as laterally. The number of fish, zoophytes, annelides, &c., kept alive in this splendid aquarium is very great, the sea anemones alone amounting to several thousand. Every one of the latter has to be fed separately by means of wooden forceps. The Brighton Aquarium is the largest yet con- structed in England, and its interior is perhaps the most ornately fitted up, and varied with natural objects. The chief corridor (that which contains the aquarium proper) extends 220 feet. The tanks are placed on each side. They are of various sizes, the largest being more than 100 feet long by 40 feet in width, and holds 110,000 gallons of sea water, or nearly as much as that of all the tanks and storage reservoir, included, of the Crystal Palace Aquarium. Indeed, this huge tank is big enough for the evolutions of porpoises, full-grown sturgeons, sharks, sea -lions, turtles, and other huge marine animals. The next largest tank is 50 feet long by 30 feet broad. This is placed immediately opposite the former. The total quantity of sea water con- tained in all the Brighton tanks is over 300,000 gallons, besides which there are storage reservoirs into which the salt water is pumped directly from the sea outside, which are capable of holding half a million C 2 20 THE HISTORY OF AQUARIA. gallons more. The salt water thus obtained, how- ever, is liable to be very turbid. This huge quantity takes about ten hours to be pumped in. In the chief corridor above mentioned the number of tanks is twenty-one. The total frontage of all is about 740 feet. Octagonal table tanks are also exhibited, in which the rarer marine zoophytes, &c., are kept, and where the process of fish-hatching may be seen going on. The most important event which has taken place in the history of aquaria, from a purely scientific point of view, was undoubtedly the founding of the aquarium at Naples by Dr. Dohrn, a German naturalist, Mr. Lloyd aiding in its construction. The expense was borne almost entirely by himself and a few personal friends, but the result has been scientifically successful. Dr. Dohrn's idea was to make it a kind of zoological station for the ob- servation of the life-histories of marine animals ; analogous to astronomical observatories or stations. The ground floor of the building covers 8000 feet, there being a story above fitted up as a zoological dissecting room and laboratory, for the use of natu- '•• ralists. Further, Dr. Dohrn here receives students ! of natural science, the animals examined being ob- tained by dredging expeditions which are carried on from time to time. A certain number of students' "tables" were offered to various Government scientific societies at a fixed sum. Some of these were taken NA PLES AQUA RIUM. 2 1 by the Universities of Oxford and Cambridge for the use of students who might gain the right of study. The aquarium is fitted up with the usual tanks, &c., on the ground floor, and is opened to the public at a certain charge. The money thus received is applied towards defraying the expenses of the institution. Already some highly important natural history work has been done here, notably researches in the em- bryology of certain fishes. Shortly after the Naples station was founded, a similar aquarium was commenced at Penekese Island, the expense of which was defrayed by the munificent act of one of the New York merchant-princes. It was placed under the charge of Professor Agassiz, who un- fortunately died almost before the institution had got into working order. The undertaking is now under one of the Professor's sons, and the scientific investi- gations promised to be of great service to zoology, but it has not hitherto proved so successful as was expected. There is no reason in the world why all our great public aquaria should not prove as effective to pure scientific research as they already are to the public educationally. Practical students might be attached to each, whose time could be devoted to zoological research. The time of the curator, how- ever scientific may be his attainments, must neces- sarily be too much taken up by the general manage- ment for him to carry out observations which require constant and assiduous watching. THE HISTORY OF AQUARIA. The Manchester Aquarium was the largest inland institution of the kind, before that at Westminster was built. It was opened to the public in 1874, and for a long time was under the direction of Mr. Saville-Kent, F. L. S. The main portion of the building occupies a superficial rectangular area of 150 feet in length, by 72 in breadth. At each extremity of the saloon are placed the two largest tanks. These occupy the entire width of the room 40 feet ; so that they are capacious enough to con- tain living animals of considerable size. The total number of tanks at present existing is sixty-eight. These have a linear frontage of nearly 700 feet, which approaches very nearly the total frontage of the Brighton tanks. It is contemplated adding a series of tanks between the arches separating the saloon from the corridors so as to raise the total number to one hundred. This would give an additional frontage of 224 feet, and so far would render the Manchester Aquarium the most extensive in this respect. In addition to the above, there is a number of octagonal table tanks for fresh water and the smaller and rarer marine animals. The Southport Aquarium was opened the same year as the latter. It is well situated in the town, which may be regarded as the "Brighton" of the Lancashire coast. The climate here is milder than anywhere in Lancashire, so that it is a place to which invalids resort in the winter — hence the " Winter WESTMINSTER AQUARIUM. 2$ Garden " which is associated with the aquarium. The tanks are constructed much on the same plan as those at Brighton, and have a total linear frontage of 500 feet. Another aquarium at Blackpool, an adjacent town on the same coast as Southport, has tanks pos- sessing a frontage of 250 feet. Other aquaria are in course of erection at Scar- borough, Yarmouth, and elsewhere. That at Yarmouth is intended to have show tanks in which 200,000 gallons of sea water will be held. The building is now nearly completed, and is expected to be opened to the public during the present year. The exten- sive aquarium at Westminster is in connection with a " winter garden." Although opened to the public the tanks are not yet fully stocked. The show tanks will hold 150,000 gallons of water, whilst there are storage reservoirs underneath capable of holding 600,000 gallons more. Public aquaria are further either being built or contemplated at Rhyl, Rothesay, Plymouth, Torquay, Southsea, Tynemouth, Mar- gate, Scarborough, Ipswich, and elsewhere ; and there cannot be a doubt that within the next few years, most of our large seaside, if not inland, towns will possess these useful and attractive institutions. 24 PRINCIPLES OF THE AQUARIUM. CHAPTER III. PRINCIPLES OF THE AQUARIUM. THERE can be no question that portable fresh-water ,and marine aquaria may become sources of endless amusement and instruction ; and at the same time be so constructed as to ornament the rooms in which they are placed. Fresh-water aquaria especially, may be arranged so as to add to the usual cheerful aspect of our English homes. The sight of the moving objects, and of the green water-plants covering and shooting above the surface of the water is undoubtedly cheering. Invalids, or people of sedentary habits, who are much confined within doors, might find com- fort and enjoyment from keeping an aquarium. The antics of its little inhabitants, and the little care required to keep this miniature world in a healthy condition, will draw off their attention from many an hour of suffering or care, and unconsciously develop a love for God's creatures. To children, aquarium keeping may be the means of imperceptibly teaching .those feelings of humanity towards the lower animals which have hitherto been too much neglected. The "hunting instinct" is strong in most CRUELTY TO ANIMALS. 25 boys, and a love of natural history might direct this so that it would benefit man and beast alike : not unfrequently it assumes the character of unconscious cruelty, and the possession of might soon passes into the belief that its exertion is right The thoughtless- ness with which children often torture flies, worms, &c., must undoubtedly be the means of partially developing a nature that ultimately finds a pleasure in inflicting pain, or in causing death. There is only too much truth in the sarcastic remark that when an Englishman is on a visit to the country and writes home to say he is enjoying himself, you may be sure he is killing something ! Anything which can neu- tralise this tendency to cruelty, or develop a more tender regard for the lower organised of our fellow creatures, becomes a means of moral education. This, we contend, might easily be brought about by keeping an aquarium, and interesting children in the funny ways of its inhabitants. Many people think a fresh-water aquarium "only gives a lot of trouble, and is always getting out of order ! " Of course, there is no denying that both these conditions may easily be brought about ; but cannot the same excuse be made for declining any- thing else ? An aquarium properly constructed, and peopled with proper inhabitants, gives very little trouble indeed. A few minutes now and then are quite sufficient to keep it in that active, healthy order which gives so much pleasure to the possessor. A 26 PRINCIPLES OF THE AQUARIUM. little common sense exerted in its arrangement cannot fail to ensure the perpetual comfort of its inhabitants. There are few " hobbies " which require less trouble, and as a rule it will be found that whatever "trouble" is caused, is due to ignorance, in not understanding the habits of aquatic animals and plants and the con- ditions under which they best thrive. But, it may be asked, how are we to know all about such matters, unless we gain experience by first keep- ing aquaria ? This is very true, but unfortunately a great many people do not persevere in keeping them, but exchange them for some other amuse- ment as soon as difficulties arise. Perhaps they have not understood the elementary principles on which a streamless aquarium should be constructed, and so in putting it together wrongly they have been laying up for themselves an endless store of trouble. Or they have not taken the slightest pains to understand whether the animals and plants they have placed in the water were likely to agree there. An aquarium thus stocked has looked well up to the evening of the same day, but next morning it has presented all the appearance of a field of battle. In the darkness of the night, or rather in the early morning, a dire con- flict has taken place. Each animal has been battling with its fellow, the weakest has gone to the wall, and only a few gorged cannibals remain of the too large stock with which the aquarium was peopled the day before ! These are eyeing each other with suspicious RESPIRA TION OF PLANTS. 27 anger, and it is evident at a glance that the war will be waged to the death. We cannot too distinctly remember that a stream- less aquarium is a little world, shut off, as it were, from the great world outside. The water, the animals, and the plants have to be so adjusted that no extra- neous addition is required. The marvellous principles of adjustment of animal to vegetable life, and con- trariwise, which holds good all over the surface of the globe, is as much in active operation in a portable aquarium as on a planet. Under the influence of sun- light the aquatic plants obtained from some stream or pond give off oxygen. You may frequently see it, in little bubbles, clinging to the stems and under surfaces of the leaves. We need not say that this gas is vitally necessary for the support of animal life. Plants there- fore provide it. On the other hand, it is equally im- portant that the carbonic acid given out by all animals shall be disposed of, or put out of the way so as not to injure the creatures that have breathed it, after the fashion of the Black Hole at Calcutta. Plants per- form this function ; and not only do they absorb the deleterious gas, but they actually require it for their sustenance and growth, as much as animals do the oxygen ! It will be seen, therefore, that in the knowledge of this fact we have the means of adjusting a collection of aquatic animals and plants, in the vessel we call an aquarium, so that there shall be constantly kept up a 28 PRINCIPLES OF THE AQUARIUM. mutual compensation. The next important thing is to know how many animals we can place in a tank where there is already a certain number of plants. Unfortunately, people who commence keeping aquaria are usually too anxious to have as many and as varied a stock of animals as possible, and most of the evil which overtakes their endeavour arises from such over-stocking. It is evident that if there are more animals in the aquarium than there are plants to provide oxygen for, all of them will have to go short. This means universal sickness, and that pitiful gasping for air which is often to be seen in over-stocked aquaria. Before long it ends in death. Perhaps one or two of the weaklier die first. Their bodies lie on the bottom and are not removed. De- composition sets in, and the water becomes fouler than ever. A white fungus — or rather the first stage of growth in many microscopic fungi — covers the bodies of the survivors. The aquarium becomes a painful scene of misery, disease, and death — a too vivid picture of similar conditions among humanity when the latter is horded in fetid and over-populated alleys, short of air, short of food, short of fresh, pure water ! What wonder that many an enthusiastic young naturalist has been so thoroughly depressed by his first mistake terminating so fatally, that he has cast away the contents of his first aquarium, and never tried afterwards ! And yet all this evil has been wrought for want of a SICKL Y A Q UARIA . 29 little consideration, and perhaps because people could not resist the temptation to have as many animals in the aquarium as possible. There is one sure rule of guidance to a beginner in these matters — have too few animals rather than too many. They will com- pensate for numbers in the sense of health they seem to enjoy, in their vivacious gambols, and sprightly habits. The fishes are here, there, and everywhere, instead of always gasping with open mouths on the surface of the water.* The newts are frolicking about, or basking on the surfaces of the leaves and stones. Still, although we give this advice, it is to be followed with a degree of caution, for the over-stocking of an aquarium with plants is liable to overthrow the balance of life with almost equally fatal results. If there are too many plants the principle of natural selection soon sets in ; the weakly or badly adjusted species die off; the water becomes foul, and perhaps assumes a thick green hue. There is a ready means of checking such a disaster, however, for the evil re- sulting to an aquarium from excess of plant growth is not so rapid in its effects as when it is over-crowrded * Mr. \V. A. Lloyd has produced twelve practical articles on Aquaria in the following numbers of ' Cassell's Popular Recreator/ published in 1873 an<3 1874 : — 4, 8, 12, 16, 20, 24, 30, 32, 35, 38, 41, and 45. They are illustrated by fourteen woodcuts, of which eight are especially valu- able as representing, drawn to an accurate scale, how many creatures, and of what kinds and sizes, can be maintained in aquaria of a named water capacity, of a given water distribution as to surface, and at a given temperature. 30 PRINCIPLES OF THE AQUARIUM. with animals. Moreover, when the first symptoms set in you can neutralise them by adding another animal — a small fish, a young newt, a few tadpoles, or two or three water snails, adding them one by one, and waiting to see the results. In this manner you proceed as a chemist does when weighing some valuable or important medicine. He trickles a little at a time until he has attained the exact weight to a feather. Excessive growth of plants may be kept down in one or two ways. First by modifying the light. Owing to the strong desire to see as much as possible of what is going on in the aquarium, many people expose it as much to the light as they can. And, as they have perhaps fallen into the other mistake of constructing three, if not four, of the sides of glass, it follows that the amount of extra stimulus to which the plants are exposed far exceeds that which influences them in a state of nature. In a pond all the sides are dark — the light can only get into the water from above, or through the surface. In a river or stream the sides are always dark, and, though the light can reach the bottom from behind and in front, it passes wholly from overhead. When there is too much glass used in the construction of an aquarium there is a temptation to use the glass : this means exposing the aquarium to light, so that the latter passes completely through it on every side. For this reason bell-glasses are specially to be shunned for fresh-water aquaria. The young beginner has only to RES TOR A TION OF AQ UARIA. 3 1 remember that the secret of his successful preservation of animals and plants lies in his imitating natural conditions as much as possible. And a very slight consideration will show him that round bell-glasses, and square tanks, having three or four glass sides, are as far removed from these as they well can be, unless in shady places. It is this intensity of light which promotes the rapid growth of the greenish film coating the inner surfaces of the very glass through which you want to watch your animals, as if it were a judgment inflicted on your unscientific taste ! This is not the worst of it : the same lowly-organised and rapidly-developing algcg will mantle your water plants with their green slime, and strangle and suffocate them in folds of sickly-looking greenery. At the slightest sign of anything of this kind occurring, the aquarium ought to be put away from the light. A few days in a darker corner will soon restore it to its healthy con- ditions, if only the disease has been taken in time. Another means of keeping down the excessive growth of aquatic vegetation is by introducing more marsh snails, such as Paludina, the larger species of Pla- norbis (P. corneus\ &c. These crawl over the inner surfaces of the glass and clean it, removing and de- vouring the green film ; they also keep down the tendency to too rapid growth in Anacharis, Callitriche, &c., on account of their fondness for the young and growing shoots. 32 PRINCIPLES OF THE AQUARIUM. Another evil threatening all aquaria results from not attending to the temperature of the water. You see tanks placed full in the sunlight of the window, where the inhabitants are most exposed to the light and heat. We have noticed how the light thus received encourages the undue growth of vege- tation ; now we have only to remark on the sickly condition of the water when it is so thoroughly and directly heated by the sun. The temperature is raised far beyond what it could be in a pond or a stream. In the former the sides and bottom are always dark and cool, and in the latter the greater ease with which the sun can heat the shallow water is compensated by the constant change of the water in running. In an aquarium placed in the full sunshine it is evident that the animals and plants alike are exposed to most unnatural conditions. With the elevation of the tem- perature there is attended a less capacity for the water to contain the mechanically -mixed oxygen given off by the plants, or even to absorb it from con- tact with the air at the surface. Animal matter de- composes more readily, and thus the water becomes sooner fetid. What the student ought especially to observe, therefore, is that his fresh-water aquarium is placed where the temperature of the water varies as little as possible. It ought never to fall below 40° or rise higher than about 60°, if he desires to keep a healthy stock of animals and plants. A well-constructed aquarium ought to continue CLEANSING AQUARIA. 33 in the same state for years. It is a common error among those who have had no experience in these matters (and very likely the notion has fostered the idea as to the great trouble which aquaria give) that the water ought often to be changed. Nothing of the kind. A well-balanced aquarium, one that has eventually " got into good working order," wants no water added to it except what may be lost by evapora- tion. If proper care be taken, even this may be reduced to a minimum. The best plan is to have the top covered with a plate of glass. It may be loosely placed there, and ought never to be fastened down, else there would be no means of getting at the con- tents of the aquarium. Such a plate of glass lessens the evaporation, and protects the surface of the water from dust. If you desire that the aquarium should be further ornamental, this may easily be done (with one of sufficient capacity), by having a fountain playing in the middle. Fewer aquatic plants are then required to aerate the water, as the fountain does it mechani- cally, entangling films of air on the surface of every drop of water thrown up. The plants may then be ornamental, such as the water violets (Hottonia palustris\w&\.zx plantains (Alisma plantago\ &c. All that is required is a wide-mouthed bottle, in the cork of which are three holes though which the glass tubes seen in the sketch pass. C reaches nearly to the bottom, whilst the other two pass only through the cork. A is a wide, funnel-topped tube. C is bent at D 34 PRINCIPLES OF THE AQUARIUM. the top, and has there attached to it a piece of long indiarubber tubing. The cork and tubes should fit perfectly. In order to set this easily improvised Extemporised Fountain for small Fresh-water or Marine Aquaria. fountain in action you fill the bottle. When it is full, continue pouring water gently into the funnel until it is above the level of the bend in the tube C. A little will then flow over into the long leg of the FOUNTAIN FOR AQUARIA. 35 syphon E. The water will of course continue to flow until the level of the water in the bottle falls below the mouth of C. The tube B is for the escape of air whilst filling. A very short experience will enable the student to work this cheap fountain, and it is evident it will flow for a greater or less space of time according to the magnitude of the feeding bottle and the bore of the indiarubber pipe,N which is. bent upwards at its extremity for the purpose of throwing the water into the air. It is true, more water is wasted by evaporation in this manner, but this is a difficulty easily met, as sufficient fresh water can always be put in the service or feeding bottle. The fresh-water aquarium may be made prettier and more ornamental than it hitherto has been, with aquatic flowering plants, if only pains be taken to render their conditions of growth natural. There is no j reason why we should not have aquatic gardens of this kind in our rooms. The dust which accumulates when the presence of such plants renders a closely-fitting glass plate impos- sible, can easily be removed now and then by gently laying pieces of blotting paper, on the surface of the water. The dust adheres to it, and it is then easily removed. Or it can be skimmed off by using the edge of a sheet of writing paper. By a little skill and care, we might easily possess semi-aquatic gardens in which miniature fountains are made to play ; and the whole rendered a fit and healthy habitat for such creatures as can best be supported. D 2 36 FRESH- WA TER A Q UARIA. CHAPTER IV. CONSTRUCTION OF FRESH-WATER AQUARIA. THE construction of a moderate sized, portable fresh- water aquarium may be as cheap or as expensive a matter as a person thinks fit, or his pocket can afford. They can usually be purchased at the natural history dealers' shops in London and elsewhere ; but perhaps one learns more of the conditions under which the animals we propose to keep will hereafter live, if we have the aquaria constructed under our own super- intendence. Having fully taken into consideration the principles which ought to guide us in maintaining aquatic animals and plants, the next thing is to be sure the aquarium will not leak ; and that it contains nothing in the materials composing it which are at all likely to be poisonous. Under the direction of a car- penter or plumber, any of the aquaria of which we give illustrations may be constructed. One of the cheapest, perhaps, is that shown in Fig. 2, and, by a little alter- ation in the internal details of rockwork, &c., it may be used for marine or fresh- water objects as the owner thinks fit. The back and sides are composed of strong, half-inch wood, dovetailed together. The bottom is thicker, and is screwed to the framework. The front CHEAP AQUARIUM. 37 only is occupied with plate glass, which is let in by a kind of " rabbit and bead," as carpenters call it. The whole of the interior of the woodwork, back, bottom, Fig. 2. Cheap Portable Fresh-water or Marine Tank. and sides, is then coated with pitch to the thickness ; of about one-eighth of an inch. Hot pitch is also run I into the "rabbit," and the plate-glass front pressed well against and into it. If a wide beading is then run all round the top, the aquarium will be completed. Thus constructed, the whole expense will not exceed 14^. or 15.$-. Before stocking it with animals and plants, the tank should be seasoned in rain water for a week or two ; and can then be used without any fear of leakage or harm. A costlier method of constructing a tank on the same pattern is to have the bottom, back, and sides of slate, instead of wood, with a plate- glass front as before. There can be no doubt that aquaria with flat sides are much better than round bell-shaped glasses. They do not distort the objects when moving about, 38 FRESH-WATER AQUARIA. after the fashion in which goldfish often present themselves to our notice in the ordinary globes. For a few pond snails and a plant of Myriophyllum, &c., as " stock," an inverted bell-glass with a wooden base, such as is shown in Fig. 3, may be used. It should be remem- bered, however, that only a very few objects can be thus accom- modated ; but if the owner have self-denial enough to forego the temptation of over-stocking the glass, such an aquarium may be healthily kept, and will even form a very pretty and lively little " Stock" Glass. ornament to a room. Again, a darkened bell-glass may be used as part of a mote ela- borate attempt (Fig. 4), in which, by means of an ordi- nary cheap wire stand, it may occupy the centre and be surrounded with the ordinary flowering plants with which we are in the habit of decorating our rooms, A glass sheet protects the surface of the water in the aquarium from dust. The late Dr. Lankester, who was one of the best and earliest writers upon aquaria, showed in his ' Aquavivarium ' that such an arrange- ment as this might be very easily and cheaply car- ried out. Another inexpensive tank, which answers well for window purposes, providing the sides and back are made of opaque material and not of glass, is shown in Fig. 5.' The top may be fashioned of wood or zinc BELL-GLASS AQUARIA. 39 slightly perforated, and should have a narrow plate of glass let into the top. If the front only be made of Fig. 4. Flower-stand, with Bell-glass Aquaria. glass, the light will not prove too strong. We have used this kind of tank both for fresh-water and marine 40 FRESH-WATER AQUARIA. objects. It should not be placed in a window having a south front, as the light then is too strong, and will develop that pest of aquaria, a thick opaque green- Fig. 5- Oblong Tank for Window Aquarium. ness, do what we may. A northern aspect is always the best for the glass frontages of aquaria to face, whether they be placed in windows or in rooms. In the construction of square or polygonal aquaria it is of course necessary above all things that the sides should be perfectly water-tight. Leakage is a source of annoyance and untidiness in a room, besides in- terfering with that balance of animal and vegetable life which is sought to be sustained in the water. The following will be found a good receipt for making a cement that will keep the sides and joints of a tank perfectly water-tight : fine white sand, one part ; litharge, one part ; resin, one-third part, mixed into a ROCKWORK FOR AQUARIA. 41 paste with boiled linseed oil, and applied unstintingly . A little rockwqrk is always an additional element of attraction in an aquarium, especially if fish or amphi- bia are kept. In fresh- water aquaria, however, it is never required to the extent it is in marine. When built up loosely, the darker places afford a screen from a too intense light, and those creatures which cannot bear it will soon discover such retreats. But this adaptation applies more to marine animals than the fresh-water forms of which we are especially treating. Newts love to crawl upon a stone or piece of rockwork projecting above the water, in order to bask in the sun; but this they will do if the water plants are strong enough to bear them on the surface of the water. The best and most harmless material for rockwork is pieces of pumice-stone, fragments of melted glass bottles, and such fragments of vitrified bricks as may be picked up in any brick-kiln. These should be fastened together with Portland cement. In order to make the contents of the tank as light as possible, one or two inverted flower-pots may be fastened to the bottom. If the inverted edges be so broken as to form a passage through, then the interior will serve as a dark cave to any of the animals re- quiring such a retreat. The holes (now uppermost) should not be filled up, for the water within the inverted pot will be kept colder, and thus a healthy current action between it and the surface water may be set in action through the holes. Flower-pots thus 42 FRESH- WA TER A Q UARIA. serve a double purpose. They render the rockwork built around and over their external surfaces (except where the edges are broken at the bottom to form a tunnel, and the usual opening in the middle of the inverted base) lighter than it would be if it were heaped up, one solid piece on another. And we have already seen that the colder bottom and warmer surface waters will set up a feeble vertical current action. If aquatic plants are intended to form a part of the stock contents of the tank, the best plan is to procure them when young from some dyke or pond, and plant them in flower-pots. These flower-pots may be hidden among the rockwork ; nay, the latter may be loosely fastened around them by means of Portland cement so as to completely conceal them. Such species as the water violet, water plantain, water soldier, and arrow- head grow best when thus treated ; and as their flower- ing spikes ascend above the water whilst their leaves are mostly either submerged or floating, they form very pretty accessories to the larger fresh-water aquaria.* In the arrow-head, water ranunculus, and several others, the floating or surface leaves are of a different size and shape to the submerged leaves. All the plants just mentioned require a good depth of soil to be planted in, and their transference to flower-pots prevents * Such aquatic plants ought not to be kept where gas is lighted at night, as they are then unduly forced, and pine away from not obtaining their necessary repose. DUCKWEEDS. 43 the necessity of filling the bottom of the tank with the depth of soil or mud in which they require to grow ; and as these vertically-growing plants might be placed around the sides or at the ends of the tanks, more room would then be left for the evolutions of fishes or other aquatic animals. Hence, rockwork in the centre of fresh-water aquaria is to be shunned, as it both inter- feres with the movements of the objects and prevents us witnessing them. The surface of the water should, if possible, be partly covered with vegetation, for it keeps the water cool and forms a retreat for the smaller inhabitants, and also to some degree prevents undue evaporation. One or two of the many species of duckweed (Lemna) are useful in this respect, for none Fig. 6. Fig. 7. Ivy-leaved Duckweed (Lemna trisulca). Lesser leaved Duckweed (Lemna minor). of them need any soil. They derive what nutriment they require from the water in which they float, suck- ing it by means of the slender rootlets which may be seen let down from the layer of green frond-like 44 FRESH- IV A TER AQUA RIA . leaves. These roots terminate in a spongy base, through which the work of absorption is carried on. In forming aquaria wherein it is intended to grow aquatic plants, a good deal of attention ought to be paid to the fact whether such plants require much or little -soil. With the exception of the duckweeds, all require some, if only to anchor their roots in. But this mud should be dispensed with as much as pos- sible, on account of the tendency there is to thicken the water whenever fishes or other animals stir it up. The great water beetle (Dyticus) very often does this, especially in the night time ; and so you awaken some morning to find the water, which was clear the night before, in what seems a hopelessly muddy condi- tion ! Little if any soil is required by the Anacharis (a Canadian plant), one of the most useful an aqua- rium keeper can have if kept in proper bounds, for it grows only by shooting or budding, never by seeding, and many aquatic animals, fishes especially, are very fond of nibbling at the young green shoots. Another plant, equally useful and even more beautiful, is the star-wort (Callitriche), which requires a little sediment for its roots to be planted in. The leaves of the star-wort are much used by fishes and amphibia for depositing their spawn upon. The water crowfoot (Ranunculus aquatilis) requires little soil for its roots, but its needle-shaped leaves soon branch through and fill up the interior of the tank if too strong and old a plant be introduced. It is worth trying a little of this SOIL FOR AQUARIA. 45 common plant, however, if only for the sake of the pretty kidney-shaped floating leaves and its brilliantly white and abundant flowers. The best soil that can be selected for the purpose of covering the bottoms of fresh-water tanks is fine river sand, in which may be mixed a few small round stones. All should be well washed, or they may be the means of introducing into your aquarium objects you never bargained for, which will upset the equilibrium you so much desire to commence and maintain. A few pieces of charcoal mixed with it, are serviceable in ab- sorbing all decaying organic substances. These, how- ever, should be removed from time to time, when it is supposed they have taken up as much organic matter as they can. Charcoal also prevents foul smells, and generally acts as a deodoriser. Too much of it, how- ever, is likely to be injurious. In fitting up an aqua- rium the soil should be placed after the rockwork has been constructed and the water plants rooted in their concealed flower-pots. To prevent the soil being washed up and the water rendered muddy, the water must be poured in through the finely perforated rose of an ordinary watering can. The fresh water commonly used for drinking purposes will do, and this is perhaps better than if obtained from a pond, where there is likely to be much more diffused vegetable matter. The water weeds, both potted and planted, ought also to be well washed before they are trans- ferred, otherwise fish, amphibian, or molluscan spawn 46 FRESH- WA TER AQUARIA. may be adhering . to their stems and leaves, so that they are afterwards hatched. Let us suppose that all these directions have been attended to, the plants are growing in the recently poured in water, and the latter is clear and transparent. Now let it remain in this state for a day or two, when the plants will have recovered from the shock occa- sioned by their transference, and the water will have been tolerably well charged with the oxygen they have given off. Then add one or two animals, a couple of minnows or newts, and a water snail or two, and watch the results. From what we have already said in the last chapter you will at once perceive whether there is a redundancy of animal or vegetable life, and be able to modify their relationship accordingly. When there is evidently a balance, endeavour to keep it. All the objects, animal and vegetable, which you have stocked the tank with, are mortal, and will sicken and die. You must at once remove dead bodies, or they will taint the water. A pair of wooden forceps will be handy for picking them up from the bottom where they are sure to be found occasionally lying. A little hand-net will also be found useful both for removing specimens and procuring them for further and minuter investigation. If fish are kept they require a little food, but the quantity is so small that it does not do to provide it for them artificially. On no account get into the habit of feeding fish or newts with pieces of raw beef, or even FOOD FOR FISHES. 47 earth worms. Whether they will accept them or not depends upon their capricious humour, and if they are not eaten they only accumulate on the bottom and foul the water. A much better plan is to keep as many snails as you possibly can. Their spawn is a favourite food with fish, and what with that, animalculae, ento- mostraca, and the fresh shoots of aquatic plants, they manage to make all the feeding they require. If fresh- water animals have to be artificially fed the best diet is the blood- worm (Tubifexrivuloruin), which is to be found in many ponds and streams. Many fish eat it greedily, and it has the advantage of being an aquatic worm, so that if it be not eaten at the time you put it in the tank, it lives to be eaten another day ! The fine blood-red colour of this worm is due to the false- blood being visible through the thin skin. We have seen that the gradual change of the water to a greenish hue is due to the presence of minute vegetation which the undue light has stimulated into existence, and that the remedy for this was to sub- due the light until the evil was overcome. Now we have to notice another unhealthy condition of things to which the inhabitants of a fresh-water tank are liable. Occasionally the weeds are covered with a white hairy slime, and the water gets thick with a muddiness which is evidently due to the same cause as the condition of the plants. Perhaps you will also notice the fishes gasping on the surface, as if they were unwilling to breathe the foul air mixed with the 48 FRESH-WATER AQUARIA. contaminated water. These symptoms are due to want of air ; and when you perceive them, at once remove the aquarium to where it will receive an extra stimulancy from sunshine and oxygen. If this does not immediately remedy the evil, remove one or two of the fish or newts, or other of the larger animals to a temporary glass, such as is shown in Fig. 8, where there are plants of Vailisneria, &c., growing. This is one of the best oxygen- giving, fresh-water plants we have, and may be used in small tempo- '^ rary jars or glasses for the purpose of so aerating the water that it * acts as a restorative, and the glass Vallisneria is the best re- thus serves as a kind of COnva- storing plant. lescent hospital. If a large aqua- rium is kept, or more than one, an infirmary of this kind will be found very useful.* We repeat it, that the only successful way in which aquatic animals and plants can be maintained in a healthy condition, is by endeavouring as far as possible to imitate natural conditions. This, however, presumes * It will be noted that all the foregoing directions apply only to streamless fresh-water aquaria. When opportunity affords (as it often may do) of constructing them so that the water may be conducted by a pipe from the usual household supply, and a constant circulation and aeration can be kept up, much labour will be saved, and the objects will appear more healthy and active. • •. VALLISNERIA. 49 a more intimate knowledge of natural history than most people possess, and in such cases, therefore, all we have to do is to attend to the above general in- structions, until such time as experience will have been able to suggest some other course. Every set of animals and plants has different habits to another, and we should never fall into the error of supposing that because we have been successful with one group, exactly the same treatment cannot fail to be effective with another. To the aquarium keeper as well as to the profound naturalist, the motto of Longfellow equally applies — " Learn to labour and to wait" 50 AMPHIBIANS AND FISHES. CHAPTER V. AMPHIBIANS AND FISHES OF THE FRESH-WATER AQUARIUM. IT needs little scientific knowledge to perceive that an aquarium keeper is likely to be far more successful if he attempt to keep a few animals, than if he over- crowd his tank with many. It cannot be too strongly insisted upon, that more than half the misfortunes and so-called " bad luck" which are ordinarily experienced in the keeping of aquaria, are due to over-stocking. When a few objects only are kept it is surprising how healthy and vigorous they appear. Moreover, they sooner get tame, or rather accustomed to their keeper, than when they are numerous. It is always best to keep more than one individual of the same species if the tank be large enough, otherwise there is a sense of loneliness suggested which detracts from the pleasure of preserving animals ; and before long one sees that the solitary pets feel this themselves. Two small fishes or newts are always preferable to one. Nearly all our native species of animals can be thus kept in captivity. Recently such amphibians as the pretty yellow-spotted salamanders, and those still more curious creatures the Mexican axolotls have been in- SALAMANDERS. 51 troduced, and aquarium keepers can now purchase them alive at any of the London naturalists. Still, we doubt whether either of these exhibit so much intelli- gence as our own newts, or if they exceed them in beauty. The great water newt (Triton cristatus), Fig. 9, Fig. 9. Great or common male of Water Newt (Triton cristatus). notwithstanding the roughness of its warty skin, has a bright orange colour on the under part of the body which gives it a very attractive appearance. Its move- ments in the water are even more graceful than those of fishes. These animals have long been regarded with dislike and suspicion, and not many years ago farmers believed they could cause rheumatism and paralysis to cattle by creeping over their limbs. Even yet this superstition may be found lingering in out-of-the-way corners of England. We have ourselves heard myste- rious diseases and complaints in cattle attributed to their drinking pond water in which newts were known to be abundant ! The readiness with which country lads pelt newts to death even yet, is a " survival " of this ancient and ignorant prejudice. We need not say how thoroughly without foundation is this notion, or descant on the cruelty to which it has given rise. E 2 52 AMPHIBIANS AND FISHES. The presence of a serrated crest along the back is characteristic of the males both of this species and that of the smooth newt. The latter, however, may easily be identified by its smooth skin and smaller size. Both male and female of the great warty newt are easily tamed. We have kept them until they would come to the top of the water and take a worm from our fingers. They are voracious feeders, but it is best not to supply them with too much food. When they are in season, the tadpoles of the common frog will be found the best diet to give them. These do not taint the water as worms are apt to do when they die ; and it is very interesting to witness the schemes and pursuits the newts indulge in to capture their second cousins. It will be as well not to keep this species and the smooth newt (Lissotriton punctatus) in the same tank, otherwise the latter may fall a victim to the ready appetite of the former. Even if it does not it is placed in hourly dread, and shelters itself so that it can rarely be seen. All the newts use their verti- cally flattened tails for swimming. The weakness of their legs on land adds to their reptilian appearance, for they are obliged to crawl, and are by no means so agile as the lizards for which they are frequently mis- taken. On hot summer days you will see the newts, with their legs extended, floating and basking on the surface of the water. It is only in the spring and summer months that NEWTS. 53 the males of these two species of newts have the dorsal crest fully developed. Like many other animals, birds especially, the sexes are reduced to a common likeness during the winter. When the warmth of later spring begins to be felt, it is astonishing how quickly the dorsal crest, and the characteristic colours and the spots of the males, are developed. In May and June these will be at their height, for the females are then depositing their ova, singly, in the folds of the leaves of the water plants. The eggs are soon hatched, and, as is well- known, the tadpoles are en- Fir I0 dowed with external gill- tufts (Fig. 10). The great warty newt is the best for the fresh-water Tadpole of Newt (three months aquarium, on account of its greater fondness for the water. It rarely leaves it, except to bask on the leaves, or on some stone. Hence it is as well to have a little rockwork projecting above the surface of the water in which these newts may be kept. During winter, it will lie torpidly at the bottom of the tank ; but if the latter be always kept in doors (as it ought to be), the period of hybernation will be very brief. Perhaps the reason why the crest is lost in winter is that it becomes absorbed, in lieu of food, by the system, to maintain the action of the involuntary organs. There is a popular error that the tadpoles of frogs and toads 54 AMPHIBIANS AND FISHES. drop their tails and gills when they leave the water for the land. The real fact is that both these organs are absorbed and utilised, and are not dropped or shed at all. The smooth newt is quite as common as the warty, and its habits are perhaps quite as interesting to the observer. The dorsal crest of the male is not toothed, Fig. ii. Adult male of Smooth Newt. Fig. 12. Adult female of Smooth Newt. like that of the warty newt, although it is wavy in its outline. Both male and female indulge in graceful evolutions, and not unfrequently may be seen chasing each other in frolicsome sport. The female is exceed- ingly cautious in selecting the proper places for the deposition of her eggs ; and the process of laying them singly or in pairs, and afterwards of folding up the leaves of the plant around them, so as to screen them TADPOLES. 55 Fig. 13- from the keen eyes of other aquatic animals on the look-out for food, is very interesting. If the plant be present, the female smooth newt always seems to prefer the leaves of the Callitriche for this purpose. This plant is very common, and is one of the best that can be selected for fresh- water aquaria. The crea- ture maybe seen examining one leaf after another until she has selected one that appears to answer her pur- pose better than the rest. The eggs are laid at an interval of three or four weeks. Under the micro- scope these eggs become very interesting objects, in- asmuch as the transparent membrane allows every stage of the development to be plainly seen. The claspers are used by Callitriche, showing leaves folded , , over eggs of Smooth Newt. the young tadpole to hold on to any object there is in the water, for it is only after a brief experience that it is able to regulate and control all its own movements. Water fleas (Daphnid) and the blood-worms already 50 AMPHIBIANS AND FISHES. mentioned, are the best food for the smooth newts. If these are supplied in abundance the newts will rarely leave the tank. Indeed, there is much reason Fig. 14. Fig. IS- Tadpole in egg eight days after laying. The arrows indicate the current motion caused by the cilia. The dotted lines show Development of tadpole in t the increased growth eleven days after the seventeen days after the laying of n egg was laid. egg. Fig. i 6. Earliest stage of the free tadpole of smooth newt — #, claspers ; />, fore- leg partly developed ; c, circulation of the blood ; d, transparent fin ; e, branchiate, or gill-tufts. to suppose that one cause of their leaving is the ab- sence or shortness of food supplies. They are very curious animals, and will come to the inner surface of the glass of the tank to examine anything unusual, DE VEL OP ME NT OF NE WTS. 5 / or even when you are observing the movements of any of the creatures through your magnifying glass. One of their habits is that of casting their skin, which is sloughed off whole, so that it can be afterwards collected and mounted. This process usually takes place when the breeding season is over, and male and female are assuming their winter skins. We have one or two other native species of newt which are much rarer, and more locally distributed than the above, which would do equally well as objects for the aquarium. These are the straight-lipped warty newt (Triton Bibronii\ and the palmated smooth newt (Lissotriton palmipes), found near Tooting. The de- velopment of the spawn of frogs and toads might also be usefully studied in an aquarium, although care would have to be taken that the quantity introduced was not too great for the aquatic vegetation to supply with oxygen. Very little attention has hitherto been paid to the development of these common objects, but there is no reason to believe it would be less interesting than that of the newts. Although resem- bling each other so much, the spawn of frogs and toads may easily be identified by the fact that the former occurs in lumps and the latter in single strings. The eggs of toads are about a quarter of an inch in diameter, and usually smaller than those of frogs. Where there is an abundance of newt or frog spawn developing, several small fishes might be preserved to keep down its undue development, always providing 58 AMPHIBIANS AND FISHES, that the capacity of the tank is sufficient to allow of necessary vegetable growth to provide them with air. Of all the favourite species the goldfish has long been most domesticated, so that now, like the canary among birds, it seems to be better adapted to confine- ment than even to a free roving life. It will answer admirably in a tank supplied with Anacharis, the tender shoots of which it eats with great relish. This and an occasional blood-worm will serve for all the food it requires. Where fish are kept the utmost care should always be taken that no bread or biscuits are ever given to them, as these not only injure the fish, but contaminate the water by their speedy decompo- sition, unless the water is exceedingly well oxygen- ated. Care has also to be bestowed upon the Ana- charis in such tanks as may contain it, for, as its only method of reproduction in this country is by budding, the latter process is apt to take place so vigorously as speedily to fill the water with a densely-crowded mass. It may always be made to grow by planting a sprig in a flower-pot containing soil, and placing this among the rockwork, so as to be hidden away. Undoubtedly those of our native fishes which are easiest to obtain and domesticate are the stickle- backs and the minnows. We have several species of the former, some of which will live equally well in fresh and salt water aquaria ; and as some of them indulge in the unfishlike recreation of nest-building, they become really very interesting objects when the S TICKLEBA CKS. 5 9 tank is clear enough to enable one to witness their habits of life. They are, moreover, pugnacious little fellows, and will attack other aquatic animals, or get up fights among themselves, as if they had been geographically limited to the " Emerald Isle." You Three-spined Stickleback engaged in nest-building. may witness the male fishes carrying bits of weed, &c., in their mouths, and building up a heap in some corner in this manner. This work finished, their next task is to induce some of their female companions to come there and deposit their eggs. Whilst engaged in this courtly office the males assume the most lovely pris- matic hues, especially about the head and shoulders. The females deposit their eggs or spawn, and then leave it to their male companions to defend the spot 60 AMPHIBIANS AND FISHES. against all spawn-loving fish, until such time as it is hatched. Even then the labour is not over, for we may see the paternal fish hovering about the young fry with the greatest anxiety, and valiantly running tilt against all other animals, those of their own spe- cies included, who may be desirous of making further acquaintance with them. The commonest of these little fish is the rough-tailed or three-spined stickle- back (Gasterosteus trachurus). The male will attack Fig. 18. Rough-tailed Stickleback (Gasterosteus trachurus}. anything that comes near his nest, even the carnivorous water tigers and water beetles. Another species is Gasterosteus semi-armatus, very common in some streams and rivers, and this also constructs a nest, and generally adopts the habits above described. Nearly allied to the sticklebacks in many respects is the Miller's thumb, or river bull-head (Coitus gobio). In many rivers they are very abundant, so there is no difficulty in procuring them. In the aquarium they are active and wary little animals, loving to hide under the loose stones. The loach (Cobitis barbatula) is another interesting little fish that may be readily domesticated. As its GUDGEON, ETC. 61 barbules would lead anyone to infer, it is a bottom feeder, and its colour and markings are such as readily to hide it from observation when in its natural habitat. Fig. 19. The Loach (Cobitis barbatula}. Like the miller's thumb, it often hides under the stones, or in the interstices of rockwork, but it is by no means so voracious. In the aquarium it, as well as most fishes, is very useful in devouring any odd worm or dead insect or fragment that may have been lying on the bottom of the tank, and that otherwise j would have decomposed and contaminated the water. The gudgeon (Gobio'fluviatilis) is even a greater ' favourite with some aquarium keepers than stickle- Fig. 20. The Gudgeon (Gobio fttiviatilis). backs. It grows to a larger size, often to 6 inches in length, and is therefore a more attractive object. It may readify be identified by the pair of barbules, or 62 AMPHIBIANS AND FISHES. feelers, one on each side the mouth. If this fish is kept, the bottom of the tank should be covered with sand and gravel, not mud, or otherwise the water will be fouled by its habit of stirring up the bottom. It is a voracious feeder, and will eat up any animal garbage that may be lying about. It is best to keep several of these fishes in the same tank, as they are very social in their habits, and will not live long solitary. The minnow (Cyprinus, or Phoxinus !