276 URINARY SYSTEM. 



and a texture comparatively soft and easily lacerable : the me- 

 dullary is much closer and tougher in its composition, and evi- 

 dently exhibits a fibrous texture. The two substances are not 

 conjoined in any regular line ; but dark-red denticular prolonga- 

 tions of cortical, shoot in between the lobulated portions of me- 

 dullary substance. 



Though the ultimate or intimate structure of the kidney may 

 not be demonstrable with absolute certainty, it would appear, 

 from the results of researches of anatomists in general, that there 

 is less speculation interwoven with the accounts commonly ren- 

 dered of it, than is but too often found blended with those of 

 other complicated glandidar organs. Injections sent into the 

 emulgent arteries colour the cortical substance, but are not to be 

 detected in the medullary ; a simple fact that has led to the con- 

 clusion, that the former is principally composed of bloodvessels ; 

 at least this is the common result of the experiment. To pass 

 over the detail of the means, however, whereby we have attained 

 our knowledge, the minute structine of the kidney appears to be 

 this: — The several divisions into which the emulgent artery 

 splits in penetrating the substance of the gland, end in a multi- 

 plied number of smaller arteries ; and these form arches within 

 the cortical substance from whose convexities a still smaller set 

 come off; which miimt.e vessels proceed inward, few (if any) of 

 them reaching into the medullary part, and end in little globular 

 bodies that have been resembled to the acini of the liver, and 

 named i\\e corpora glohosa ; a sort of arterial arrangement alto- 

 gether that has been compared to grapes as they grow upon their 

 slender stalks. The corpora globosa were at first supposed to 

 be cellular: but later researches afford us reason for believing 

 that they are constituted of the vessels runnitig into them : 

 instead of terminating within them, they are continued and 

 coiled into these globular forms. From the corpora globosa pro- 

 ceed inward, in convergent radii, fasciculi of minute vessels, 

 named, from their office, the tuhuiiiainijeri ; which fasciculi are 

 so disposed in sets (commonly six or seven in number) as to 

 admit of a resemblance to so many paps or dugs, and hence 

 have been denominated the processus manunillares. These coni- 

 cal fasciculi, which take then- rise in the cortical part, constitute 

 the medullary substance of the kidney. The papillcc, the apices 

 of the mammillary processes, are received into little membranous 

 sacs, varying in form and size, denominated the inj'undibula, into 

 which the secreted fluid is distilled through the orifices of the 

 tubuli uriniferi perforating the papillae : the number of infundir 

 bula, however, is not regulated by that of the processus mammil- 

 lares, for one sac may embrace two or even three papillaj. The in- 



