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Show 0] AusoitPTiON general/r. ‘e Of A B s o u r 1' i o s 31 Hum/1y. (lies, by which they take up the lluids in which their orifices are immersed; and carry them into the blood vessels. The beginning of absorption may or may not resemble the attraction of capillary vessels in dead matter, but the power of propelling the fluids depends on the living power of the vessels. Dead animal matter quickly admits of the absorption from porosity, and allows itStlfto be pervaded by fluids, and we call this tea/ring, or Irmn‘udaliml. Dr. Hunter himself at one time believed that certain fluids in the living body got out of vessels bytransudation; and that the fluid found on the sur- faces ofthe dillerent viscera, and in all the internal cavities, was formed by transudatéon of the thinner fluids through the coats of arteries; for he ob- served, that the arteries in the dead body, injected with water till they bedtime quite turgid, in a very little time after became flaccid, having allowed the fluid, as he said, to soak through their sides into the cellular membrane. Albinus appears to have entertained a similar opinion, and suspected that the pcrspired fluids oozed through the coats of the arteries in the skin. " Quid ni penetraret per mollia nostra humidaque, quutn calentis aqua: va- " por per durtun siccumque corium eo modo penetrat 2'" Professor Mekel, til the Memoirs of the Academy of Berlin, also maintains the doctrine of transnda‘tion through the cuticle. " Quoique inaccessible aux vaisseaux, " .«a nature est pourtant telle qu'il transmet le liquide dont il est imbu, a" peupres comme pourroit le faire un euir mince humecté." tier, in a number of places in his Physiology, admits a similar transu- damn e.' fluids; and says the oil soaks through the peritoneum, for exam- ple, ple, or pleura, and assists in forming the lubricating, fluid of these surfaces. He believes even that the vapour of the subjacent rectum penetrates through the vesicular smninalcs, and gives the peculiar odour to the semen. I am sorry to oppose such respectable authority; but I am of a contrary opinion, and join with Dr. li‘ordycc in believing all parts of a living body impervious but by vessels, for the following reasons :--If fluids get out of vessels by transudation, they may get into them by the same means, and the first step, at least, in absorption, might thus depend on an animal poto. sity: but this, I am confident, is not true. In dead bodies the fluids certainly transude: the vessels, in lo. its; life, lose the property of confining their fluids. Wherever the contained fluid is sulicicicntly coloured, we can easily demonstrate this. Bile, for example, is either brown, yellow, or green; and blood ofa dark red: the first tran- sudes through the gall-bladder, and tinges the transverse arch ofthe colon, the duodenum, and pylorus, in short, all the neighbouring parts, of the same colour with itself; the second also transudes through the coats ofveins, and makes the stomach, for example, which is naturally white in the living body, of a dark red. Thin fluids injected into the blood-vessels, in the (lead body, also transude: glue dissolved in water, and thrown into the corollary veins, transudesinto the cavity of the pericardiutn, and jellying retains the shape of that me; the same glue injected into the veins of the pia mater, transudcs into the ventricles of the brain, and when cold and jellied, retains the figure of these cavities: but nothing of‘this kind takes place in living bodies. Suppose the cavity ofthe abdomen, in a living animal, intentionally or accidentally laid open, none of the former examples of transudation will be observed; the bile will not be found transuding through its own capsule, nor tinging the colon or pylorus; the stomach will be seen perfectly white. Mr. Hunter's experiments on the blood-vessels ofliving animals, to be men- tioned hereafter, prove that coloured fluids, injected into the veins of the intestines, neither escaped through orifices opening on surfaces, nor transuded through their coats. That the lluid found on surfaces, is'not from transudation through the coats of arteries, I am persuaded, from attending to the following circumstances :-The sweat, or the fluid found on the surface of the body, and which comes more immediately under our observa- C 2 tion, "35""m" i; . DESIDERATA. Vegetables and animals absorb, however, 111 a dtderent manner, and on an entirely different principle from inanimate matter; for as in the first sense of absorption they talte in and propel forward. This absorption in vegetables is performed by livng and irritable vessels, and depends on the presence of a stimulus. Most plants absorb both by their roots and branches, some principally by their leaves; amongst the last is the C.\(' rt' s, the surface of whose stems have the properties of leaves. This absorption in animals is a property in certain vessels of their bo- s ‘ .mz," ,. ', Porolngv, and that it would have been one of the linest things amongst his ti - |