GLANDS. Ill 



known of its nerves and lymphatics (PL XX. 

 fig. IV.). 



The proper coat of the kidney consists of a dense Fibrous coat 

 interlacement of connective and elastic fibres ; its 

 internal surface is united to the cortical substance of 

 the organ by minute vessels, and delicate trabeculse of 

 its own tissue ; its outer surface is continuous, by 

 means of slender fibrous processes, with the mass of 

 adipose tissue in which the gland is imbedded ; at 

 the bottom of the hilus it becomes continuous with 

 the calices. 



The secreting duct of the kidney, or ureter, is ureter. -\ 

 expanded above, where it forms the pelvis and calices, 

 and terminates below at the bladder. On examining 

 into the structure of its walls, we find, proceeding 

 from without inwards: 1st, a fibrous tunic; 2d, a 

 layer of smooth muscular fibres composed externally 

 of longitudinal and internally of circular fasciculi ; 

 3d, a mucous membrane, with its epithelium in strata, 

 and becoming sensibly thinner where it passes from 

 the surface of the calices upon the papillae. Of this 

 epithelium the deep cells are very regularly oval, but 

 those nearer the surface are variable both in size and 

 shape, and resemble exactly what are called cancer 

 cells ; the epithelium of the bladder, which is con- 

 tinuous with the ureter, presents the same physi- 

 ognomy; that of the urethra is composed of cylin- 

 drical and oval cells, of regular form. 



In the unmixed urine, as it escapes from a healthy urine. 

 kidney, histologically, there is nothing to be recog- 

 nised. It is a liquid in which we find no organized 

 element, unless it be here and there a cell, acciden- 



