KIDNEY. 



water, the papillae dilated, the ureters enlarged above the 

 ligature, and empty below, the bladder not containini^ a 

 fingle drop of urine." The phenomena of difeafe confirm 

 the conci'jfions to which thefe trials lead: obftniftions of 

 the invters, arid fiippreffion of the aftion of the kidnies, en- 

 tirely Hop the urinary difcharge, whatever quantity of fluid 

 the patient may drink. 



This aficrtion of the exittence of a fliort communication 

 between th.e domach or bowels and the bladder, againlt the 

 evidence of anatomy and experiments, is founded on an af- 

 fumption which we confider to be highly queftionable. We 

 are fo far from allowing that the abforbents and blood-veflels 

 arc inadequate to the explanation of the phenomena, that 

 we believe the very reverfe to be true. We believe that the 

 great abforbing fui-face afforded by the alimentary canal, 

 together with the infinite number of abforbing vefTels, and 

 the diameter of the thoracic duft, fully account for the 

 conveyance of fluids into the blooj ; and that the large fize 

 of tlie renal arteries, which muft circulate the whole mafs of 

 blood through the kidnies feveral times in the courfe of a 

 minute, with the great number of the uriniferous tubes, very 

 fatisfaSorily explain the fecretion of urine in any quantity 

 of 'which wc have examples. If thefe paffages, which are 

 obvious to our fenfes, and large enouijh to allow a con- 

 fiderable quantity of fluid to pafs through them, cannot 

 tranfmit the urine with fufRcient celerity, how fhall we ex- 

 pect that a greater quantity can pafs through canals, which 

 muft be beyond all comparifon fmaller, iince no diffedlor 

 even conjecfures that he has ever feen them ? There is an- 

 other and flill more fatal objedion to thele opinions : the 

 fluids voided in thefe cafes are urine, of a very aqueous 

 kind indeed, but ftill urine ; — ilill that peculiar animal fluid, 

 w-hich is fecreted only by a kidney. Now, if there be a 

 direct paffage from the ftomach to the bladder, we ought to 

 void, according to the nature of our drink, tea, wine, 

 punch, cyder, &c. We mutl fuppofe, therefore, the ex- 

 iftence of an unknown kidney to convert thefe different 

 fluids into urine, as well as of an unknown paffage to con- 

 vey them to the bladder. The exiftence in the urine of par- 

 ticular properties, derived from certain articles of food, will 

 prove nothing in this cafe, until we have been convinced 

 that they cannot have been imported by the medium of the 

 gener;il circulation. Expofure of the body to the vapour of 

 turpentine will affeft the urine, without its introduction in- 

 to the rtomach. (See the experiments under the article 

 Inteoumexts. ) What are the fecret paffages by which 

 this is conveyed, in fuch a cafe ? 



The uHkc is regarded as a fluid entirely excrementitious ; 

 as confining of materials, which are either ufelefs in the ani- 

 mal economy, or which, if retained, would be actually 

 prejudicial. The fluids which wc drink dilute the folid 

 food, reduce it to that ftate in which it conftitutes the chyle, 

 and are abforbed with it. Probably a confiderable portion 

 is taken up immediately from the alimentary canal, without 

 undergoing the previous change into chyle ; fince copious 

 drinks of'en augment the urinary difcharge much fooner 

 than the formation of chyle could be effected. The fuper- 

 fluous fluid, thus introduced into the blood, is feparated by 

 the kidnies, and very fpcedily feparated, when large quan- 

 tities are drunk : hence the chief component part of the 

 urine is water. The organs of the body are conflantly un- 

 dergoing changes in their compolltion : they receive frefh 

 particles from the blood, while the abforbing fyflem re- 

 moves the old ones ; I'o that there is a perpetual movement 

 over the whole body of combination and decompofition. 

 Again, a fimilar change is inceffantly carried on in the ani- 

 mal fluids. The lymph of the cellular texture and the 



ferum of the circumfcribed cavities are at all times in thi? 

 kind of circulatory motion. Thefe old materials are con- 

 veyed into the blood by the abforbents, and feparated from 

 it in the kidnies, in order to be thrown out of the body. 

 They feparate it under the peculiar form denominated by 

 the French chemifls urce ; which matter exceeds in amount 

 by many times all the other fahne fub fiances difTolved in the 

 urine, and bellows on that fluid its colour, odour, — in a 

 word, all its peculiar charaftcrs. We fhall anticipate, from 

 this view of the matter, what the refearches of modern che- 

 miflry have moll clearly proved, that the component in- 

 gredients of urine are very numerous : it exceeds, in this 

 refpeft, ail the other animal fluids. A particular account 

 of its fenfible charadlers and chemical compofition will be 

 found under the article Ukin'E ; and that of the concretions 

 occafionally formed in the urinary paffages under Stone. 



No fecretion exhibits fuch fignal variations as this : the 

 term urine, therefore, is applied to fluids differing in almoft 

 every circumflance from each other. The nature and pro- 

 portion of its ingredients are not alike in the fame individual, 

 at the difliercnt periods of life. Peculiar charafters diflin- 

 guifh it in the foetus, the boy, the adult, and the old fub- 

 je£l : they differ in the fame day, according as a perfon is 

 cxpofed to heat or cold, as he is inactive or ufes much 

 bodily exertion, according to the nature and quantity of 

 the food ai;d drink, and the length of time after meals at 

 which it is voided ; the Hate of health, particularly of the 

 ftomach, and other digeftive organs, and the paflions of the 

 mind, have alfo cc&ifiderable influence. 



The kidnies and bladder of the foetus contain a very fmall 

 portion of fluid, which can hardly be deemed urine : it is al- 

 moft entirely aqueous, rather vifcid and turbid, and has no 

 fmell or talle. In the firil years of life, the colour is not 

 deep ; the acrid and odorous properties are but flightly 

 marked. As the motionof compofition prevails, in a'moll 

 all the organs, over that of decombination, the quantity of 

 uree is fmall. The earthy phofphates, particularly that of 

 hme, are not prefent, or in very minute quantities. While 

 offification is incomplete, this fubftance is required for the 

 developcment of the bony fyftem. In the adult, where the 

 growth of the body is complete, the refidue of nutrition is 

 more abundant.* all the properties of the urine are more 

 ftrong. It contains falts, earthy phofphates, phofphoric 

 acid, urce, and uric acid, according to the defcription in 

 the articles already referred to. The falts and the animal 

 fubftance increafe in the old fubjett ; the phofpate of lime 

 is very abrndant. 



The m.odifications produced in the urine by heat and cold, 

 w^hich include alfo the effects of exercife, ai:d the influence 

 of the feafons, are not the refult of any dirett aftion on the 

 kidnies, but arife from the operations of thefe caufes on 

 the cutaneous functions. The relations between the urine 

 and the external and internal exhalations are peculiar to this 

 fecretion. In proportion as we pcrfpire more abundantly, 

 the urinary evacuation is diminiflied ; and the fame circum- 

 flance is obferved in confiderable dropiies. From this cha- 

 rafter, which belongs exclufively to the fundtion of the kid- 

 nies, naturally arife the frequent varia:ions in the quantity 

 of the urine ; while the other fccretions are nearly always iu 

 unifoi-m proportions. Expofure of the furface to cold, or 

 inactivity, is attended not only with an incrcafed quantity o£ 

 urine, but with alterations of its other properties : it is pale, 

 not acrid, nor ftrong in its fincll. Warm;h, with free per- 

 fpiration, or ftrong exercife, diminiflies the quantity, and 

 renders it more highly coloured, acrimonious, ar.d odorous. 

 Slighter changes of an analogous nature may be remarked, 

 in winter and fummer. (See l>TEGUitiiNTS.J, When tlie 

 7 quantity 



