60 



in excess, to destroy the blood globules aud to cause irritation of the 

 kidneys by the resulting hfemoglobiu excreted in the urine, and of 

 glycogen too abundant to be burned up in the system, which in- 

 duces saccharine urine (diabetes). Any disorder leading to impaired 

 functional activity of the lungs is causative of an excess of hippuric 

 acid and allied bodies, of oxalic acid, of sugar, etc., in the urine, which 

 irritate the kidneys even if they do not produce solid deposits in the 

 urinary passages. Diseases of the nervous system, and notably of the 

 base of the brain and of the spinal cord, induce various urinary dis- 

 orders, prominent among which are diabetes, chylous urine, and al- 

 buminuria. Certain affections, with imperfect nutrition or destructive 

 waste of the bon^^ tissues, tend to charge the urine with i>hosphates of 

 lime aud magnesia, and endanger the formation of stone and gravel. 

 In all extensive inflammations and acute fevers the liquids of the urine 

 are diminished, while the solids (waste products), which should form 

 the urinary secretion, are increased, and the surcharged urine proves 

 irritant to the urinary organs or the retained waste products poison 

 the system at large. 



Diseases of the heart and lungs, by interfering with the free onward 

 flow of the blood from the right side of the heart, tend to throw that 

 liquid back on the veins, and this backward pressure of venous blood 

 strongly tends to disorders of the kidneys. Certain poisons taken with 

 the food and water, notably that found in magnesian limestone and 

 those found in irritant diuretic plants, are especially injurious to the 

 kidneys, as are also various cryptogams, whether present in musty hay 

 or oats. The kidneys may be irritated by feeding green vegetables 

 covered with hoar-frost or by furnishing an excess of food rich in phos- 

 phates (wheat bran, beans, pease, vetches, lentils, rape-cake, cotton-seed 

 cake) or b^^ a privation of water which entails a concentrated condition 

 aud high density of the urine. Exposure in cold rain or snow storms, 

 cold draughts of air, aud damp beds are liable to further disorder an 

 already overworked or irritable kidney. Finally, sprains of the back 

 and loins may cause bleeding from the kidneys or inflammation. 



The right kidney, weighing 23^ ounces, is shaped like a French bean, 

 and extends from the loins forward to beneath the heads of the last two 

 ribs. The left kidney (Plate IV), resembles a heart of cards, and extends 

 from the loins forward beneath the head of the last rib only. Each con- 

 sists of three distinct parts, (a) the external (cortical) or vascular part, in 

 which the blood-vessels form elaborate capillary networks within the 

 dilated globular sacs which form the beginnings of the secreting 

 (uriniferous) tubes and on the surface of the sinuous secreting tubes 

 leading from the sacs inward toward the second or medullary part of 

 the organ; (6) the internal (medullary) part, made up in the main of 

 blood-vessels, lymi)hatics, aud nerves extending between the notch on 

 the inner border of the kidney to and from the outer vascular portion, 

 in which the secretion of urine is almost exclusively carried on; and 



