which air is delivered; this ends at Q, but is continued by a length of rubber tubing sufficient to reach the centre of the tank at its lowest point. Into the open end of this rubber tube is inserted a small cylindrical plug of wood, well dried wood of the common lime being very suitable for the purpose; through the almost microscopic vessels of this the air is driven. The delivery tube (P) passes out of the tank through a notch in the glass cover, bends downwards outside the tank and is attached by a rubber connection to the tube (K) from the separator. The air is thus made to enter the tank in a stream of exceedingly fine bubbles which rise to the surface of the water and there spread out radially in all directions. The currents so produced in the tank are indicated by arrows in the figure; it will be seen that every part of the water is moved and no stagnant areas are left. This is one of the main factors in the success of this system. (4). It is now only necessary to describe the relation of those parts of the system already mentioned one to the other. For convenience the separator should be placed close to a sink or drain, into which the water issuing from it can pass. It should also be kept as near to the floor or ground level as possible. The Y-tube by which the air is drawn in should be directly above the separator, and at as great a height above it as can be arranged; if a copious and satisfactory air-supply is to be expected this should not be less than twice the length of the one inch tube of the separator. Where possible it is best to instal this part of the apparatus in the open-air (the tube F may conveniently be run down the outside wall of a house). It is inadvisable to place the air-inlet near the ceiling of a room where foul air is apt to collect. The aquarium itself may, of course, be placed in any suitable position, but it should always be borne in mind that a room subject to much fluctuation in temperature will not prove satisfactory for the purpose. Multiple Aquaria. Where a number of tanks are to be aerated it is convenient to provide a length of brass tubing into which are screwed and soldered an equal number of gas-cocks of the pattern fitted on laboratory benches. This is fixed behind the tanks, and the rubber connections from them slipped on to the cocks; while the pipe (K), bringing air from the separator, is attached to one of its ends, the other being plugged. In place of cocks ordinary screw-clips may be used, and it is indeed an advantage to regulate the actual air-supply to each tank by this means, even where cocks have been fitted. These s are, of course, attached to the rubber connection between the tank and the delivery pipe. We may now turn our attention to stocking the aquarium, having indicated the method of constructing it. I. Sea-water. If the aquarium is situated away from the sea, water may be obtained either from a biological station or from a dealer. The Marine Biological Station at Plymouth sends out water taken anywhere beyond three miles clear of land, charging 3s. 6d. for each carboy containing five gallons of water; the carboy is itself charged for at 15s., but this is recoverable if it is returned in good condition, while carriage by rail has also to be met. There are other Biological Stations at Millport (Clyde), Port Erin (I.O.M.), Newcastle-on-Tyne (Dove Marine Laboratory), etc. (of these the first at any rate will supply water), and some scientific dealers will undertake to obtain it. A good stock of water should be kept in hand in case of accidents; it may be stored in carboys in a cool dark place, and should keep satisfactorily provided the carboys were perfectly clean and the water a good sample in the first place. Once a tank has settled down and its inhabitants are happy, the water may not need to be changed for months, perhaps not for a year or more, except for an accident. Furnishing the Tank. Artificial sea-water is not a good thing to try unless it is carefully made up by an accurate method and with very good chemicals. If water is obtained in person by the aquarium-keeper, it should either come from a clean part of the coast or, if it must be taken near to any point of pollution, it should be collected some distance out at sea. II. Sand, Sand, stones, stones, etc. Some animals will like stones to shelter under or adhere to, especially such as are full of holes and cracks into which they can creep. Nicely coloured stones and pieces of coral also add to the effect of the tank without detracting from its utility. These can, if desired, be built up in a concrete matrix, shaped to fit the tank, into effective backgrounds and miniature caves. All stones used must be very thoroughly scrubbed and rinsed to entirely free them from any trace of organic matter which might decay and foul the water, and it is not at all a bad plan to boil them before doing so to kill any undesired organisms attached to them. Where a concrete mould is formed, a hole must be left through which the aeration tube can pass; while it must be remembered that the concrete should be allowed to set thoroughly and should be well washed for a week or unnecessary, and only add to the possible sources of contamination. Similarly, sponges and other encrusting growths should at first be rigidly barred. III. Animals. Biological stations will supply living animals if these cannot be collected personally. It is the better plan at first to keep different kinds of animals in separate tanks; after due experience a certain amount of mixing may be adopted, but this needs to be judiciously done if only to obviate one sort devouring the other. The range of creatures suitable for an aquarium such as is described here is not unlimited but is, however, fairly wide. To indicate the kinds of animals which may be expected to do well we give below a small selection, most of which have actually been kept for long periods in such an aquarium by one of us. [Photo by F. Schensky. MOLLUSCA. Periwinkles (Littorina), Top shells of certain sorts (Trochus cinerarius), Chitons, Scallops, etc. The small Cuttlefish Sepiola is interesting and may be kept; other Cuttlefish and Octopods are not good subjects. Sea-slugs are attractive, but difficult to feed, though Aeolidia papillosa can be kept if given Actinias to eat. Interesting Subjects. CRUSTACEA. Crabs do well but are inclined to be savage and to devour one another. Edible crab (Cancer), Swimming-crab (Cancer), Swimming-crab (Portunus), Spider-crab (Hyas), Shore-crab (Carcinus), Hermit-crab (Eupagurus), Squat-lobster (Galathea), can all be easily kept. Prawns and Shrimps are interesting, becoming very tame (Pandalus, Mysis, Hippolyte, Palaemon, etc.). WORMS. Fan-worms are spectacular-e.g., Sabella and Botomilla. Pomatoceros is less interesting but easy to keep and common. As a scavenger, Polynoe can be recommended. SEA SQUIRTS. Simple forms Clavellina and Styelopsis. Compound forms-Botrylloids do well if collected without injury in the first place. need meals at different intervals; crustacea and echinoderms should be fed at least twice a week; fishes three times if adult, a little every day if young; anemones from once a week to once a month, and so on. V. Temperature. In some parts of the country the water in the aquarium may become too cold in winter. This can be obviated by warming the room ANEMONES. Tealia is good, as are also Sagartia in which it is situated, though an effective hot-water and Actinia. Many rarer kinds do equally well and some of the showy foreign species have been kept. Metridium is less suitable. OTHER THINGS. Some kinds of hydroids will in time spontaneously make their appearance and will even liberate their medusae. Feeding. IV. Food. Animals in aquaria should not be fed too freely; they will do better if given only enough for their needs. Whenever possible they should be fed individually. Rejected food and excreta from the creatures must be removed from the tank as soon as noticed, to prevent any fouling of the water. In this connection the use of metal instruments should be avoided, only those made of glass or of wood being allowed to come into contact with the water or the animals. The kinds of food which can be given are many, but the best and easiest plan is to keep in one tank a stock of live mussels (Mytilus) and to feed the animals with fresh mussel-flesh. In our experience most animals thrive on this diet, and we have seldom had t ything else. Different kinds of animals FIG 5. PLUMOSE ANEMONE, METRIDIUM SENILIS. [Photo by F. Schensky. circulating system to warm the tanks can be constructed from an empty paraffin can, a bunsenburner and some glass or metal tubing. In this case the tanks are best set upon hollow wooden stands and the warm pipes led underneath these. For a mixed collection of animals a temperature of about 50° F. is excellent. Control. A more difficult matter is excessive heat in summer. Placing the tanks within a larger vessel in which cold water from a tap circulates is a means of overcoming this difficulty; In it is better, however, to choose a room not exposed to the hot sun of summer, a precaution which in a majority of cases will prove sufficient. We have not space here to consider refrigerating apparatus. practice, direct sunlight upon the tanks should be avoided, except in the case of special creatures. Many anemones give their best display at night. VI. Maintenance. Before any animal is introduced into the tanks already stocked it should spend a probationary period in a separate vessel. Only when it is seen to be in good health should it be admitted to a tank already settled down and in good working order. Moreover, a sick creature may be benefited by special attentions as, for instance, frequent changes of water, special aeration and so on, which can be given in this way only. Sedentary animals adhering to stones, etc., should have the object to which they are attached thoroughly scraped and cleaned before being placed in the tank, so that nothing may remain which might decay. Animals collected. may have had a large meal prior to being caught, and should be allowed to get rid of this in the probationary tank. The aquarium once started, its maintenance is chiefly a matter of regular attention and, above ali, cleanliness. Everything must be kept clean and dirt or slime produced by the animals must be constantly removed, as well as food refuse and any dead or sick creatures. The water should be changed when it shows signs of deterioration, and the tank and its contents at the same time cleaned. Provided a good sample of water is in the first instance procured, changes in its chemical or physical condition need not necessarily be considered in the case of an aquarium of the present type; such considerations, however, are important in the case of a large aquarium. Even in a small one, although in practice one can get on quite well without controlling the hydrogen ion concentration of the water, at the same time if measures are taken to ascertain and adjust this factor, it may be expected to lead to better results. than could otherwise be obtained, in some directions at all events. The means of doing this are indicated in Sister Monica Taylor's article in the January issue of Discovery; space forbids further consideration of it here. Evaporation proceeds extremely slowly in a covered bell, and it is scarcely worth while testing this with a hydrometer or making up loss with distilled water, though this can, of course, be done if necessary. VII. Cost. We cannot give the exact cost of setting up an aquarium, so much depends upon the circumstances under which it has to be constructed; but it should be possible to fix up, aerate and stock several tanks for about £10. to VIII. Advantages. It is hardly necessary enumerate the advantages which may be gained by keeping an aquarium; we start on the assumption. that anyone who wishes to keep one will have recognized these before deciding to set one up. This article does not pretend to cover the subject of aquarium-keeping even in outline, and it must be said that it is an occupation presenting many "snags " for the unwary; we have tried to show that a small aquarium of an efficient type is possible even away from the sea, and that it can be made from fairly ordinary and accessible materials. We should like to say also that really good health can be expected in the animals, with the described system of aeration; it is not a question of just keeping them alive and nothing more. The photographs illustrating this article are by F. Schensky, Helgoland, from specimens in the Helgoland Aquarium, by whose permission they are here reproduced. As already mentioned, Tealia is a good subject for a small tank, Metridium less so; the Wolf-fish shown is only suited for a large aquarium. a large aquarium. Chrysaora can be reared in a small aquarium, but the problem of feeding it would be difficult except by the sea where a good supply of its natural food could be obtained. Two Chinese Figurines. By C. M. Bowra. (Fellow of Wadham College, Oxford). These curious figures found in Chinese graves present a problem. They do not represent a Chinese type, but are certainly statuettes of foreigners. The author suggests a Persian or West Asiatic origin. IN the last fifteen years large numbers of clay images from Chinese graves have found their way into collections in Europe and America. Usually they represent either animals or men and women of undoubted Chinese type; but there are a few rare examples which represent members of other races. I have in my possession such a specimen. It is 10.9 in. high, and made of the brittle, light-yellow clay, commonly used in figures of the T'ang period, and traces of what was once a coat of red wash survive on it in patches. (Fig. 1). The comparative slimness of the figure and the quality of the clay point to its date being in the T'ang Dynasty (A.D. 618-905). Its provenance is fortunately certain. It comes from Lo-yang, in Ho-nan, one of the capitals of the T'ang. What it represents is less certain. The figure has a beaky nose and a beard; it wears a conical hat which swells out round the temples into a thick band, and it is clothed down to the knees in a tight-fitting frock-coat; the legs are covered in loose-fitting boots, rather like snow-boots. In a small private museum in Peking there is a rather similar specimen made of a pale clay, covered with a thin lemon glaze, 11.3 in. high. This second figure (Figs. 2 and 3), has the same beaky nose, conical hat, long coat and boots; the right hand carries a pestle and mortar. The figure differs from Fig. 1 in one or two details. His moustache is thicker and his beard broader and shorter; his hat has, in front and behind, flaps which are folded up; his coat is drawn in by a belt and the toes of his boots curl upwards. In the collection of Mr. George Eumorphopoulos there are four figures not unlike these two. One is a pedlar, bent under the weight of his pack; two others are servants in tailcoats, and the fourth strikes a grimacing attitude.* All four have beaky noses and beards It might have been expected that Central Asia, the home of so many races, would have produced similar types; but it has not. The figures in the frescoes, unearthed by Sir Aurel Stein, are more like Indians than anyone else. They are clean-shaven except for an occasional moustache, and their noses are not remarkably arched; their head-dresses are of the Chinese kind and their clothing hangs loosely in elaborate folds. But farther West our type is commoner both in life and in art. The modern Kurd is not very unlike our figures, and the art of the different cultures which have existed in what is now Persia shows curious parellels to them. The same physical type is found in Achaemenid times on the stone reliefs of Xerxes. There is in the British Museum a gold plaque from the Oxus of slightly later date which represents a bearded man with an arched nose, wearing a conical hat, which falls back because he has let down the rear flap and tied it under his chin; FIG. I. and all four wear conical hats with folded flaps like Fig. 2 his coat, which falls to his knees, is fastened round the waist by a belt. In Berlin there is a silver statuette of the same period with similar features, wearing a similar hat and clothing, partly concealed under a large cloak. The persistence of the type into later generations can be seen by a glance at any series of the coins struck by the Kings of Persia and Parthia. Antiochos I, of Commagene, has much the same features and hat in the stone relief on Nimrud Dag, and an Indo-Bactrian silver bowl, dating from the third or fourth century and now in the British Museum, shows a huntsman of the same appearance and wearing the same head-gear. (Continued on page 73.) |