190 DISEASES OF THE URINARY AND SEXUAL APPARATUS 



Nephritic Stones. 



(Nephroliihiasis; Renal Calculi.) 



Nephritic stones are formed in the pelvis of the kidney and range from 

 the size of a mustard-seed to that of a pea. (Megnin found two stones 

 each weighing six and seven grammes in the pelvis of a dog.) They are 

 irregular, warty, or sharply irregular, and consist of phosphate and car- 

 bonate of calcium; in rare instances the so-called cystic calculi are found; 

 these, when first removed, are soft waxy bodies with a dull surface, com- 

 posed of triple phosphate and uric acid. 



The formation of these collections is not thoroughly understood, but 

 they are probably formed by some foreign body, such as mucus, blood, 

 fibrin, epithelium, urinary cylinders, shreds of tissue, or collections of 

 bacteria; and the salts are deposited on this medium in successive layers, 

 so that finally a large mass is formed. 



Nephritic stones may produce pyelitis, pyelonephritis, or hemorrhage 

 from the pelvis of the kidney. If the stone lies at the entrance of the 

 ureter or even passes into that canal and becomes lodged, it will retard 

 the flow of urine and even cause rupture of the ureter or pelvis of the kid- 

 ney and death from peritonitis. Frccjuently the calculus is forced along 

 the ureter, causing great agony, and finds its way into the bladder. These 

 stones are not, as a rule, diagnosed with any degree of certainty during 

 life. Symptoms of pyelitis wnth the continual passage of small stones from 

 the urethra are about the only indications that will guide the observer. 



Tumors of the Kidneys. 



These neoformations can be determined only by a manual examina- 

 tion of the kidney through the abdominal wall; they frequently cause an 

 enormous increase in the size of the kidney, particularly so in carcinoma, 

 the soft form of cancer being most frequently seen. In the pelvis of the 

 kidney and the ureters we find irregular papilla-like formations (carcinoma 

 papillomata, papilloma destruans (Kitt) ; these may obstruct the normal 

 flow of urine and cause a distention and enlargement of the pelvis of the 

 kidney and the renal ducts and an atrophy of the kidney itself. The 

 only possible relief to such a condition is the surgical removal of the 

 kidney. 



Animal Parasites of the Kidney. 



Of the various parasites of the kidney the strongylus gigas has a 

 special interest. This parasite is not unlike the common earth-worm and 



