KIDNEY, 



and at the other with the lining of the pudenda. It is 

 m:irked by five or fix lonpiifidinal lines, in the intervals of 

 which muco»is lacnnx open in rows. There may be from 

 tour to feven orifices in each of the grooves, leading to 

 canals, which are continued obliquely into the fpongy tex- 

 ture of the uretiira, and capable of receiving briftlcs. On 

 the tumid edge ot the meatus urinarius two very lar^e linufes 

 open, capable of admitting the end of a probe. The (Iruc- 

 tiire of thefe organs refembles entirely that of the lacuna; in 

 the male urethra. The mucous fluid' fecretcd by them de- 

 fends the furface of the urethra from the irritation of the 

 urine : it icems alfo to be poured out more particularly in 

 coition, or imdcr the influence of (Irong deiires. 



Befides the difference of length and fi/.e in the urethra of 

 the two fexes, arifing out of the additional fundion belong- 

 ing to this canal in the male, of conveying the fecundating 

 fluid into the vagina, the want of proftate in the female is 

 another remarkable diftiuClion. There is no foundation 

 whatever for ihc opinion of De Graaf concerning the female 

 prollate. 



Fundions of the Unnary Bladder. — The urine fecreted, as 

 we have already obferved, inceffantly by the kidnies, is 

 tranfirtitted, without interruption, through the ureters into 

 the bladder, retained there for a certain length of time, and 

 then expelled by an operation under the controul uf the 

 will. The bladder, in it!^ empty ilatc, occupies a very fmall 

 fpace, is concealed entirely within the pelvis, and has its rc- 

 kitions to the furronnding organs reduced within a finali ex- 

 tent. Its contrafted coats are thick, but all of them are 

 not equally concerned in producing this ftate of the organ. 

 T!ie ferous coat, and the cellular layer, have nothing to do 

 with it ; and the mucous membrane, incapable of a quick 

 and confiderable contraction, fonns the numerous wrinkles 

 of the internal furface, which may be feen both in living 

 animals, and in the dead fubjett. The continued contradion 

 of the mufcnlar covering produces the ftate in which the 

 empty bladder is found ; and if its coats at this time are 

 thicker than ihofe of tiie ilomach and intelliiies ; it is be- 

 caufe the mufcular fibres are ilronger and more abundant. 

 At this time there is, properly fpeaking, no cavity of the 

 bladder. The urine, depolited drop by drop, dilates the 

 organ infenfibly, and makes it conlraCl new relations to the 

 iurroimding parts. Although this dillentioii takes place in 

 every direction, except towanls the front, it is mod fcnfible 

 in the long diameter, or from below upwards. Its bails 

 prelTes on the retlum in man, and the vagina in woman ; 

 but the natural limits which the connections of thele parts 

 offer, prevent it from extending much downwards. In the 

 oppofite direction there is no obltaclc to prevent its enlarge- 

 ment : it rifes freely above the pubcs, the mufcular coat is 

 dillended, the wrinkles of the mucous membrane are effaced, 

 and the whole organ is confequently rendered thinner. 



The peculiar conformation of the ureters, at their entrance 

 into the bladder, accounts for the urine not returning along 

 thefe canals to the kidney. When the bladder is dillended 

 with urine or air, the ureters are compreffed between the 

 mucous and mufcular coats, in that portion which is included 

 between thefe coverings : aiwi the obftacle becomes more 

 complete, in proportion as the dillention of the bladder is 

 increafed. This mechanifm does not depend on any vital 

 properties : you may throw air or any fluid into the dead 

 bladder, through the urethra, but not a drop will gain ad- 

 milTion into the ureters ; force the injection, and the bladder 

 will burlt. Hence, when the urethra is impervious during 

 life, and the bladder is dillended far beyond its ufual dimcu- 

 fions, the ureters are continually adding to the collection, 

 itretclijngihe organ fo as to produce moll fevcre pains, and 



ultimately caufing rupture. If the mufcular covering be 

 dilTefted away, fluids efcape immediately. 



Thus, we have no difficulty in explaining why no urine 

 pafle« in a retrograde courfe into the ureters ; but the 

 eaufe, which prevetits it from entering the urethra, is not 

 equally obvious. Although this be the natural courfe, the 

 urinary fluid docs not pafs conllanlly tlirough the urethra, 

 as it does through the ureters : it is retained for a confider- 

 able time, both m man and in quadrupeds, and never efcapres 

 fpontaneoufly, in cither inftaiice, in the healthy flatc. After 

 a certain delay, a fenlc of inconvenience and pain produces 

 a voluntary mufcular exertion, by which it is expelled. As 

 there is an uninterrupted flow of urine into the bladder, why 

 does it not conllanlly efcape ? The voluntary aft, by 

 which we fuddenly interrupt the dream in micturition, or 

 refill an urgent defire to void the urine, is manifeflly the 

 contraction of the accelerator, which doles the bulb of 

 the urethra, and confequently intercepts the communication 

 between the bladder and the front of the canal. But we in- 

 quire the caufe which aCts perpetually, not only indepen- 

 dently of the will, but when we are not attending, evem 

 when we are aflcep, in preventing the urine from flowing 

 guttntim through the urethra, as it arrives from the ureters. 

 It is the more intcrelling to difcovrr tliis caufe, fince there 

 fcems to be in the bladder a natural tendency to contraction, 

 in virtue of its irritable powers. Hence, where a diredt 

 opening is made into its cavity, when the refilling power of 

 the neck is delloyed by paralyfis, or when an open catheter 

 is left in the urethra, the urine efcapes conflantly as it it 

 fecreted, and no accumulation takes phice in the bladder. 

 The effect cannot be produced by a fphinCter, obedient to 

 the adtion of the will, becaufe it takes place in an infant 

 unconfcious of the ufages of fociety and the laws of deco- 

 rum, and in an animal which has never been- trained to clean- 

 linefs. Both expel the urine at intervals, and in obedience 

 to a llimulus, which feems to be the natural motive of the 

 aCl. Moreover, the evacuation is fo far from being fponta- 

 neous, that it requires a confiderable effort. 



Phyfiologilts have commonly referred the clofing of the 

 urethra to the fphinfter veficx mufcle, and have confidered 

 it analogous, in every refpeCl, to the fphinCter ani. But 

 this is unfatisfaftory, when the very exillence of the part, as 

 a mufcle, is queltioned. To the aCtion of this, which he 

 acknowledges to be inadequate to the effeCl, Haller join* 

 the relative pofition of the bladder and urethra. He ob- 

 ferves, that the inferior portion of the receptacle defcenda 

 below the level of the urethra, and may confequently be 

 dilated without the urine running off through that opening ; 

 and that a greater portion of the bladder is fo placed when 

 the organ is dillended. Hence, he adds, the bladder may be 

 dillended, m fome degree, in the dead iubjeft, before its con- 

 tents will efcape by the urethra. The French anatomift;s 

 feem to be of opinion that there is fome peculiar contradtile 

 and refilling power in the neck of the bladder : this is 

 termed in the Anatomic Defcriptive of Bichat, " le refforc 

 ou la refinance organique du col ;" t. v. p. 157. Boyer 

 fpeaks of the " habitual contradlion of the fibres furround- 

 ing the neck of the bladder, and the elallic force of the 

 neck and proftate." Traitc complet d'Anat. t. iv. 

 p. 493. 



We do not pretend to explain clearly the exaft mode in 

 which this bulinels is effected. We fee no fphiixitcr nmfclc 

 adequate to the purpofe, and the cir£umltance noticed by 

 Haller will not at all account for the retention of the urhie 

 until the fundus of the bladder has afcqided far iiitq th<; 

 abdomen. We mull be contented to rccognifc the exill- 

 ence, without knowing the nature of a powerful contradtile 

 5 D / properly 



