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THE MUCUS OF THE FAUCES. THE mucus whicli lubricates the cavlty of the
This mucus Is partly swallowed with the saliva, and partly with the chewed sood but the more abundant pari, colle ned especialty in the night time, is spit out frona the molith.
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I. It lubricates the cavlty of the fauces, for theeaster deglutition of the masticated sood.
a. Itrenders the sood in manducation into a formconvenient to be s allo ed. 3. It preVenis drynes of the fauces, frona the passsing of the air during respiration and speech. s. By moistening the fauces, it prevenis and moderates this.
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THE very limpid water Which filis the anteriorand posterior chambers of the eye. The SECRETORY ORGAN appears to be thefloating vesteis of the corpus ciliare, and the exhaling vesseis of the iris. The ABSORB1NG ORGAN. When in too greeta quantity, a certain pari appears to transudethrough the pores of the cornea ; and the remaining part is carried ΘWay by the oscula of the ab -
sorbing vesseis. This humour is perpetuatly re generaled, and is it flow out by a wound of the cornea, it is in a stiori time repatred : as appears froin the extraction of a Cataract for the flaccidand injured cornea sonaetimes coalesces Wilhiri
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The QUANTITY is four or sive gratias. In theffetus it is very smali, as Ueli as in old people, and in those who are about to die ; whicli is amongst the causes of the eyes collapsing. Socopious and quick is iis secretion, that within
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18 The CHEMICO-ΡHYSIOLOGICAL Doctrine The Coessae 1ΤυENΤ PRINCIPLES appear to bevery limpid water mixed with animal gas: thus it putrefies in the air by attracting the agote. Someliave found alitile soda and culinary sali init. The UsΕ of the aqueo us humOur. i. The rays of lighthaving penetraled the Cornea, it transmits the focus through the pupil to the crystalline lens, but refracts the rays of light Iesis to ards the axis than the trans parent
a. It distends the transparent cornea, and retainstite crystalline lens and vitreous humour iniheir placeS.
THE CRYSTALLINE LENS.I HE lentiforna, pellucid body, inclosed in a
membranaceous capsule, and siluated in a peculiarfovea in the anterior sui face of the vitreous hv
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Iis FicuRE is like a lentit, but the anterior suriace is plain, and the posterior convex. Iis circumference iS circular ; and iis diameter, rathex more than four lines. Ιts SP EciFIC GRAVITY, is most frequently Dur grairas. Its densio is greater than Water, as it not only snks to the bottona in fountain, but also
faetus, becoming gradually harder in the adult, d quite hard in old age. The FABRic of the CRYSTALLINE LENs, is lamellous, for by macerating it in spirit of wino Or vinegar, aboVe two thous and concentric laminae, Iaying one urn another, like the leaves of a book, may be separated with a scalpel. These lamellae consist of parallel fibres, united together by transnverse cellular si bres. This very delicate tela cellulosa is distended Uith a Deo limpid aqueous θιid called AQUULA.
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go The CHEMICO-PHYSIOLOGICAL Doctrine The Secretory organ os this aqvula appears tobe formed by the very sine and pellucid arteries, or ramuli arising from the central artery, Whicli persorate the posterior surface of the crystalline Iens. It is probable that the abundant aqvula is carried bach by the absorbent vesiels.' alcohol of reine and acid liquors, the lens is rendered opake, and is condensed by congela-
In Miled fissi, the exterior cortex of the lens 4s rendered opake and Ullite, but the nucleus remainS pellucid. UsE It transmiis, and somewhat refracts, the focus of the rays of light to the vitreous humour; for the refraelite power of the crystalline lensis not much greater than that of water.
THE VITREO US HUMOUR. THE pellucid vitris orna body which filis the
vhole bulb of the eye bellind the crystalline lens
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Iis DEN si TY in respcet os iis sige is smali. Thus placed iapon letters it moderately enlarges them, but less so than the crystaline lens. Its STRUCTURE is membrana Ceous and cellular, filed with innumerable smali drops of very linapid ater, contained in an equat number of litti e celis of the hyaloid membra ne ; so that it resembles a singular species of tremulous jelly. That the whole of this vitreous substance is composed of smali celis, externalty broad but nar-
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8a The CHEMICO-PHYSIOLOGICAL Doctrine vomer lowards the Center, and whicli haVe a com . munication one With another; Mould appear front
The ExcRETORY ORGAN of this aqvula is sormed of the pellucid ramuli of arteries, running to the vitreous body frona the central artery. The abundant aqvula is returned by the oscula of the absorbent vesseis. In hot water it is rendered rather opake; hut
quickly again becomes limpid. It is induraled, and dilated by frost.