A I. 



A1/.OON. 



104 



A. rtlyrtHt, found everywhere in dry, exposed, barren situations, 

 and is of very littlr value to the farm or, except for it* earliucm ; the 

 other, A. aUxt, is equally abundant in mar.Jiy places, where it (mint 

 a valuable pasture. Under the name of Irish Fiorin Onus, thu 

 species ha* beeii the object of much attention from experimental agri- 

 culturists, some of whom bar* extolled iU qualities Tory highly M a 

 marsh-fodder; but the experience of other* does not confirm their 

 opinion ; nor doa it appear to thrive in England so well u it is 

 represented to do in Ireland, where its rigour i* such as to hare led to 

 the belief that the Iriah plant is a distinct species, called A. Hotonifcra. 

 In England it is best known, along with A. rulytru, uuder the name 

 of Quitch, or Quicks, and is generally extirpated as a troublesome 

 weed, in consequence of the rapidity with which, by means of its 

 creeping, rooting, vivacious stems, it spreads and overruns pastnre- 

 and garden-ground. 



AL [BHADTPUS.] 



AIR-BLADDEK, a peculiar organ with which the great majority 

 of fishes are provided, and by which they are enabled to adapt the 

 specific gravity of their bodies to the various pressures of the super- 

 incumbent water at different depths. It is composed of a lengthened 

 sac, sometimes simple, aa in the common perch, sometimes divided 

 into two or more compartment*, by a lateral or transverse ligature, 

 as in the trout and salmon, and, at other times, furnished with 

 appendices, more or lew numerous according to the particular species. 

 In all cases, it is composed of a thick internal coat of a fibrous texture, 

 and of a very thin external coat ; the whole being enveloped in the 

 general covering of the intestines. 



The modifications of this organ are infinitely varied in different 

 genera and species of fishes. In the greater number of instances it 

 has no external opening, and the air with which it i found distended 

 is believed to be produced by the secretion of a certain glandulous 

 organ, with which it is in all these cases provided. This air has been 

 examined, and found to consist of oxygen and nitrogen, but with teas 

 oxygen than common air. In fresh-water fishes, the air-bladder 

 communicates sometimes with the oesophagus, and sometimes with 

 the stomach, by means of a small tube; and it is observable, that 

 in the greater number of these instances, in which it has a direct 

 external communication with the intestines, the secreting glands 

 i'b ivr mentioned do not exist ; thus giving us strong reason to believe 

 that its functions and uses are not uniformly the gam a in all the 

 different classes of fishes. A very limited number of species, among 

 others the common eel, have air-bladders not only uj>ening by an 

 external duct, but likewise provided with secreting glands ; and thus 

 occupying an intermediate station between the two larger classes, at 

 least as far as the nature and functions of this organ are concerned. 



In general, all fishes which enjoy great powers of locomotion, and 

 have occasion to pass through various degrees of superincumbent 

 pressure in their rapid transitions from the surface to the bottom of 

 the ocean, are provided with this important organ; and so indisp. 

 is it in their economy, that those which,; for the sake of experiment, 

 have been deprived of it, have sunk jEulpleaa to the bottom, and 

 there remained incapable of moving, .or even of maintaining their 

 equilibrium. But to fishes whose habits and organization confine 

 them either to the surface of the water or to the bottom of the sea, 

 and which, therefore, do not require to pass through different depths, 

 or to encounter different degrees of pressure, the possession of an air- 

 bladder is by no means so essentially requisite. Accordingly we find, 

 that all the different species of rays and Pbwmuetef or flat-fish, such 

 an skates, sules, turbots, brills, etc., which live ouly upon the coasts 

 and sand-banks at the bottom of the ocean, as well as the mackerel 

 and others which find their food entirely at the surface, have no 

 air-bladder; and so small is the relation of this nth. rui. important 

 organ to the general conformation of fishes, that we sometimes find it 

 present in one species, and wanting altogether in another of the samp 

 gmus. Although it does not appear that the air-bladder is connected 

 w.th the function of respiration in fishes, it occupies the position, and 

 has the same relations, as the lungs in reptiles. It i*. in fart. the 

 homologue of the* organs. Fishermen are well acquainted with the 

 nature and functions of tin' air-bladder, or, as they most couiiu mly 

 call it, the Svim. They are accustomed to perforate this vessel with 

 a fine needle in cod and other species which require to be brought 

 fresh to market, sometimes from a very great distance. By this 

 operation, the confined air in allowed to escape, and the ti*h << .untrained 

 to remain quiet at the bottom of their well-boats, where they live for 

 a very considerable period. Cod-sounds, which are brought in great 

 quantities from Newfoundland, are nothing more than the salted 

 air-bladders of these fishes. The Iceland fish- well as those 



of America, prepare iiringlsss of a very excellent quality from cod- 

 sound- i -y are not acquainted with the method of clarifying 

 it, which the Russians practise in preparing isin ;laas frut. 

 of the sturgeon. 



(Owen, L'rlura nn Comparative Anatomy, vol. ii.) 



Allt CKI.I.S, in plants, aro cavities in the leaves or stems, or other 

 part* containing air. In water-plants they have a very definite firm, 

 and are built up of little vesicles of cellular tiiuiic, with ax nni.li 

 regularity u the walls of a house; they u.. d'.iil.t enable the plant to 

 float They are well seen inthe stricture of the I -In 



plant* which do not float, tfie form of the air-colls is leas definite; 



they often appear to be mere lacerations of a mass of cellular sub- 

 stance, and their object is unknown ; well-known instances of th>-ir 

 presence are the chambers in the pith of the walnut-tree, and the 

 tubular cavities in the stem of the bamboo, and other Qrasaaa. 



AIIM'I. \ NTS arc so called because they possess the power of living 

 for a considerable time suspended in the air. It is however a mistake 

 to suppose that these plant* are n. . ndfd freely in the air, 



and that such a -- \ will thri, 



.mly fiist in air for a shorter or lunger period, according to the species 

 and to ntber circumstance*, but : li.-y will |rih. This 



arises from the fact that all plant* i .ntnic as well as organic 



itjnta. and alth..u-:h them latter elements can be suppli. 

 the air in tin- form .!' carUmic j./i.i, ammonia, and water, the I 

 cannot. 



There are two different tribes to which the name of Air -Plants has 

 been applied ; of which one, cuntainin;; the moss-like Tillandiia 

 tttneovta, which hangs in festoons from the branches of trees in the 

 hot damp forests of tropical Ann-nut, aud the fragrant T. j-i;>/< !<../ .-, 

 which adorns the balconies of the houses in Buenos Ayres, is called 

 by botanists Bmmeliaeat ; the other, abounding in species of the most 

 different nature and appearance, is named Orchido- 



Till within a few years the cnltu.it MM .!' Air- Plants of the Orrhii 

 tribe was supposed to be attended w ith in-upcntliV dith'culties ; and of 

 the many hundreds of beautiful Hpoc-ies that are found in foreign 

 countries, scarcely any were known in Europe, except from drawings, 

 bad descriptions, and imperfect dried specimens. 



The native country of these nirion- ploute is wherever a climate is 

 found in which heat and moisture are in excess. Within the t 

 in Asia, Africa, and America, in damp and shady forests, by tl, 

 of fountain*, within reach of the spray of waterfall*. : :i the 



branches of trees, or clinging to rocks and stones by meant of their 

 long and writhing root* creeping among moss, rearing their r 

 in the midst of brakes and o( ing tribes in all such 



situations they are found in abundance. The prinui]^l 

 them are the woods of I '. 



the Wetit Indies, Madagascar, and t _ inlands, aud the \\h-l.- 



of the Indian Archijielago ; in Java alone nearly 300 species have been 



ili-.'"\ . T. il. 



The condition* under which Air-I'lants, of the kind now described, 

 naturally thrive are 1, high temperature; 2, diffused light, like that 

 of a shady grove, and not direct solar i-ee of 



dampness; and, 4, a perfect five.l.mi from stagnant water round their 

 roots : for on the trunk* of trees or on stones and rocks no wnt. 

 lodge, and all the moisture they receive must necessarily be in the form 

 of vapour or of falling rain. And it i* to otronmMMMi of thi* i 

 that the gardener has chiefly to attend. 1 i.imp, shade, heat, and good 

 drainage will be his objects ; the three former will cause him no 

 trouble, but the latter will require him to alter entirely his usual 

 mode of cultivation. Instead of considering in what kind of soil his 

 Air-Plants are to be placed, he will endeavour to dispense with soil, 

 aud to supply its place with bits of rotten wood. 



small quantities, fragments of half-baked pottery, such as garden-pot*, 

 and the like. 



Another point of great importance in the culti\ation of thew plants 

 is, securing for them a season of repose. In their native climates, 

 although they have no winter, they have a period of comparative rest 

 from growth, and securing for them this repose whilst under culture 

 is a great secret of success. It is to a knowledge of this, taken in 

 conjunction with the circumstances before explained, that we owe the 

 remarkable improvement that has taken place in the mode of cult i 

 these plants i :ain 



(l.iudley. Obmrvationt in the Trantartiont of t!. 

 v..l. i.. New Series, p. 42, and tin- Utu,. r volumes of tin 



litffUtrr.) | Km-:! 1 1 HACK*] 



AIK VKSSKI.S, in plants, are what butaniats call ./.;<"' \'emU, 

 It is supposed by some that these are the only parts through which 

 air is conveyed into the vegetable system, and it has been pi-..\cd that, 

 in some cases at least, the air that they contain consists of a ) 

 proportion of oxygen than atmospheric nir. Hut it i.*doul>tful 1, 

 the action of these vessels i* more than local, and it is certain that air 

 has tolerably free access to many parts, as the leaves, for example, by 

 means entirely in.lcjN'u lent of the *piral vessels. 



AIIIA, a ganus of Orasaes belonging to the tribe SeiUriett, and 

 distinguished by possessing a lax panicle, two-flowered glumes, the 

 outer pale terete on the back, and a dorsal awn. There arc 

 species, but that which is best know : llair- 



UrasB. It has long and flat leaves, wit h :-. t. It 



flowers in the beginning 



It grows naturally on marshy ilump .-.-.I-, in the form ..f large tufts. 

 -. irv harsh grass, and is rejected l.y <1 -n> -*t,ic animals. It may, 

 T, be advantagfously sown OH a on 

 I'otnls and marshes for snipe and wild fowl. (Law.*.. a. Acrai- 



\ITtiNIA luftrr Mr. \V. Alton, for many years head-gardmicr at 



Kew), a KCIIU "1 plants t. lon^'in T .!/'/''/ it. The A. 



:, is a native of the Cajw of < . .:! is cultivated iu *ur 



