KIDNEY 



\'o confiderable cliange lias taken place at the time of 

 'i : although the kidnies are Hill tuberciilated, their 

 • ^ ::l- is more precilely determined, and the difTercnce of the 

 two coiilliuieiit parts is llrongly marked. There is nothing 

 remarkable about the pelvis or ureter. In the fubfequent 

 years fat is coUofted more abundantly about the kidnies : 

 thefe organs, by acquiring a thicker covering of cortical 

 matter, lofe their unequal furface, and gradually affume the 

 form which charafterizes them in the adult. The external 

 membrane becomes more denfe, and more clofely connected 

 to the furface. The other parts experience no further cliange 

 except that they partake of the general growth. In old age 

 the kidnies become foft and flaccid ; and the furrounding 

 fat is diminidied in quantity. The external membrane pre- 

 fents occalionally points of a cartilaginous confidence. 



Pbyfwl'jgy of the Kitlnies. — The minute ramifications of 

 the renal arteries, which compofe fo great a portion of the 

 cortical fubftance of the kidnies, feparate from the blood 

 the urinary fluid, \vliich is conveyed along the tubuli urini- 

 feri, and depofited by their orilices in the calyces of the 

 kidney. It then goes through the pelvis and ureter, and 

 thus arrives at the bladder. The iecretion goes on conilant- 

 ly, and the tranfmifiion into the bladder is equally conftant : 

 for there is a continual efflux, when a catheter is placed per- 

 manently in the bladder, as alfo in thofe examples of mal- 

 formation, where the ureters open on the furface of the 

 body. Ligatures placed on the ureters, or obftrucllons of 

 thofe canals by other caiifes, as, for example, by llooes, 

 demonllrate this courfe of the urine ; the tubes are dif- 

 tended between the kidney and the obftacle, and empty 

 below. 



'I'hat the urine is formed in the cortical fubftance of the 

 kidney, is the amount of our knowledge concerning this 

 part of the fubjeft ; the mode, in which the fecretion takes 

 place, is entirely unknown. This is the problem of fecre- 

 tion, towards the folution of which we have approached no 

 nearer than the above general fact fince phyfiology has been 

 cultivated. In the prefent inflance, indeed, it is not yet 

 agreed whether the uriniferous tubes be continuous with the 

 capillary arterial canals, or whether fome organ be inter- 

 pofed between them. Hence all attempts to explain the 

 peculiar nature of the urine from the ftrufture of the parts 

 n which it is formed, and to fliew how the properties of 

 this fluid agree with the ilze, direction, curvatures, &c. of 

 the canals, in which the fecretion takes place, muft be 

 founded on grounds completely chimerical, although thefe 

 reveries are fanftioned by the refpeftable autliority of Haller. 

 (Element. Phyfiol. lib. 26. fed. 4. $ 5.) Another unac- 

 fountabie error is committed by the fame phyfiologift m 

 Lis obfervations on this fubjeft. He aflerts that the urine 

 is formed in the blood, and feparated only by the afiion of 

 the kidney ; and detends the opinion by llating that this 

 fluid goes off by perfpiration, or by the llomach and intcf- 

 tines, when its ordinary pafl'age is obflructed. This noticn 

 is completely irreconcilcable with the prefent (late of our 

 knowledge concerning the chemical conftitution of the 

 blood and the urii:e ; and the alleged fafts, by which 

 it is fupported, are, to fay the leaft, of a fufpicious 

 nature. 



We may eftablifh, in the fecond place, this fa£t ; that 

 the kidnies are the only organs m the body capable of 

 forming urine, and that the ureters are the only palfagcs by 

 which fluids can be conveyed into the bladder. Yet Loth 

 of thcle points are contrary to the opinions of fome phyfio- 

 logifts. When the evacuation of the urine from the body 

 IS ilopped, fome fuppofe that it is feparated by other organs. 

 ** It appears," fays Haller (Elcai. Phyliol. Lb. 26. fed. 4. 



§ 12.), " that the friction of the circulation, and the heat of 

 the fluids produce in the blood acrid particles, tending to 

 an alkaline nature, of which the more volatile are dilfipated 

 by infenliblc perfpiration, while others, too large for tho 

 pores of tlie (kin, can be feparated by the kidnies only. 

 For, in all cafes of ifchury, where thefe particles are not 

 feparated by the urine, either fymptoms of acrimony take 

 place in the whole body, or thefe matters are thrown off by 

 other organs. Thus the fweat and perfpiration have an 

 urinous odour : or there is an urinous oedema of the whole 

 body, or urine depofited in the cellular fubftance, with 

 violent and fatal fever. In other infl:ances urine has been 

 difcharged by the falivary organs ; by the eai-s or noftrils, 

 mixed with blood ; by the mamms ; by vomiting, or 

 ftool ; or it has become mixed with the fluid of the 

 abdomen, or it has been depofited in the brain, caufing 

 cephalalgia, blindnefs, delirium, llupor, convulfions and 

 apoplexy. When fecreted into the llomach, it caufes hic- 

 cough and vomiting. Laftly, the congeftion of earthy 

 fubltances in the blood, caufed by ifchury, may produce 

 fandy matter in the fweat." That a fluid, poffei.'ing fuch 

 very pecuhar properties as the urine does, confilling of 

 fuch numerous and complicated elements, and feparated 

 ufually in a very intricate glandular ftruilure, fliould be 

 formed alfo m almoil every other kind of organic apparatus 

 in the body ; that it Ihould be feparated by the exhalants of 

 the cellular fubltance, and of the fliin, by thofe of mucous 

 and ferous lurfaces, by the veffels of the brain, as well as 

 by glandular organs, is a pofitiou lb completely at variance 

 with all that we underitand of the compolition and aAions 

 of the animal frame, that we could not receive it without 

 very unexceptionable evidence. The whole quotation exhi- 

 bits credulity rather than the deliberate caution neccffary for 

 ellablifliing fo Angular a fad, and the fubjoined autliorities 

 are not at all calculated to remove our fcruples. Perhaps 

 an urinous odour has been fometimes obfervcd in the perfpi- 

 ration ; although we believe that even this has not been 

 hitherto proved by very convincing evidence. Mull we im- 

 mediately conclude that the cutaneous exhalants have formed 

 urine ? When the biliary paffages are obft^rufted, and vari- 

 ous fluids are tinged with bile, we explain the phenomena 

 by the abforption of that fluid from its natural receptacles. 

 Will not the fame explanation fuffice for the cafes, if there 

 are any fufliciently proved, of urinous properties in the 

 other fecretions and exlialations of the body .' 



That there is fome more direct paffage from the alimentary 

 canal to the bladder, than through the abforberits, the ge- 

 neral circulation, and the kidnies, is an opinion that has 

 been partially entertained even from the moft. ancient times. 

 The very rapid manner in which the urinary fecretion ia 

 augmented by copious draughts of fluids, and the communi. 

 cation, within a very fliort time, of particular properties- to 

 the urine, by certain fubltances taken into the llomach, arc 

 the circumllances on which this opinion has bee., grounded. 

 Anatomical inveftigation has hitherto detected :u. fuch paf- 

 fage ; no diffetlor has met with any tube that could poflibly 

 ferve the purpofe of forming fuch a communication : while 

 the experiment of tying the ureters corroborates this nega- 

 tive fad, by teaching us that no urine gains admiflion into 

 the bladder, when thefe tubes are obihucted. " Claler.,"' 

 fays Haller, (Elem. Phyfiol. lib. 26. feet. 4. § 4.) " taught 

 us long ago, that when the ureters arc tied or divided in the 

 living body, the urinary bladder is found empty, and that 

 the animal evacuates no urine. This experiment has uni- 

 formly exhibited the fame refult in the hands o! fevera! vi-ry 

 pradifcd and dextrous cxjerimenters ; and Rail lately re- 

 peated it on a dgg, and found the kiduies hvoln »nd full ot 

 J C 2 water, 



