THE KIDNEYS AND URINE. 355 



membranes in general. Its epithelium is stratified and closely resembles 

 that of the pelvis of the kidney and the ureter (Fig. 240). 



The mucous membrane is provided with mucous glands, which are 

 more numerous near the neck of the bladder. 



The bladder is well provided with blood and lymph vessels, and with 

 nerves. The latter are branches from the sacral plexus (spinal) and hypo- 

 gastric plexus (sympathetic). A few ganglion-cells are found, here and 

 there, in the course of the nerve-fibres. 



THE EXCRETION OF THE KIDNEY : THE URINE. 



Physical Properties. Healthy urine is a perfectly transparent, 

 amber-colored liquid, with a peculiar, but not disagreeable odor, a bitter- 

 ish taste, and slight acid reaction. Its specific gravity varies from 1015 

 to 1025. On standing for a short time, a little mucous appears in it as 

 a flocculent cloud. 



Chemical Composition. The urine consists of water, holding in 

 solution certain organic and saline matters as its ordinary constituents, 

 and occasionally various matters taken into the stomach as food salts, 

 coloring matter, and the like. * 



Table of the Chemical Composition of the Urine (modified from Becquer el). 



Water . 967 



Urea 14.230 



Other nitrogenous crystalline bodies 



Uric acid, principally in the form of alkaline 

 urates, a trace only free. 



Kreatinin, xanthin, hypoxanthin. 



Hippuric acid, leucin, tyrosin, taurin, cys- 

 tin, etc., all in small amounts and not 

 constant. 



Mucus and pigment. 

 Salts : 



Inorganic 



Principally sulphates, phosphates, and chlo- 

 rides of sodium, and potassium, with phos- 

 phates of magnesium and calcium, traces 



10-635 



8-135 



of silicates and of chlorides. 

 Organic 



Lactates, hippurates, acetates and formates, 

 which only appear occasionally. 



Sugar . a trace sometimes. 



Gases (nitrogen and carbonic acid principally). 



1000 



Reaction of the Urine The normal reaction of the urine is 

 slightly acid. This acidity is due to acid phosphate of sodium, and is 



