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goiter, may be similarly explained. The untnown poison wliicli pro- 

 duces goiter presumably leads to such chaages in the blood and urine 

 as will furnish the colloid necessary for precipitation of the urinary 

 Baits in the form of calculi. 



Classification of Urinary Calculi. — These have been named according 

 to the place where they are found, renal (kidney), uretral (ureter), vesical 

 (bladdev), urethral (urethra), aud 2}reputial (shenth or prepuce). They 

 have been otherwise named according to their most abundant chemical 

 constituent, carbonate of lime, oxalate of lime, and 'phosphate of lime cal- 

 culi. The stones formed of carbonates or phosphates are usually sn^ooth 

 on the surface, though they may be molded into the shape of the cav- 

 ity in which they have been formed; thus those in the pelvis of the kid- 

 ney may have two or three short branch-like prolongations, while those 

 in the bladder are round, oval, or slightly flattened upon each other. 

 Calculi containing oxalate of lime on the other hand have a rough- 

 open, crystalline surface, which has gained for them the name of mul, 

 berry calculi, from a supposed resemblance to that fruit. These are 

 usually covered with more or less mucus or blood, ])roducfcd by the irri- 

 tation of the mucous membrane by their rough surfaces. The color of 

 calculi varies from white to yellow and deep brown, the shades de- 

 pending mainly on the amount of the coloring matter of blood, bile, or 

 urine which they may contain. 



Renal Calculi. — These may consist of minute, almost microscopic de- 

 posits in the uriniferous tubes in the substance of the kidney, but more 

 commonly they are large masses and lodged in the pelvis. The larger 

 calculi, sometimes weighing 12 to 24 ounces, are molded in the pelvis 

 of the kidney into a cylindroid mass, with irregular rounded swellings 

 at intervals. Some have a deep brown, rough, crystalline surface of 

 oxalate of lime, while others have a smooth, pearly white aspect from 

 carbonate of lime. A smaller calculus, which has been called coral- 

 line, is also cylindroid, with a number of brown, rough, crystalline 

 oxalate of lime branches aud whitish depressions of carbonate. These 

 vary in size from 15 grains to nearly 2 ounces. Less frequently are 

 found masses of very hard, brownish white, rounded, pea-like calculi. 

 These are smoother, but on the surface crystals of oxalate of lime may 

 be detected with a lens. Some renal calculi are formed of more dis- 

 tinct layers, more loosely adherent to each other, and contain an excess 

 of mucus but no oxalate of Inue. Finally a loose aggregation of small 

 masses, forming a very friable calculus, is found of all sizes within the 

 limits of the jjelvis of the kidney. These, too, are in the main car- 

 bonate of lime (84 to 88 per cent.), and without oxalate. 



Symptoms of renal calculi are violent colicky pains appearing sud- 

 denly, very often in connection with exhausting work or the drawing 

 of specially heavy loads, aud in certain cases disappearing with equal 

 suddenness. The nature of the colic becomes more manifest if it is 

 associated with stiffness of the back aud hind liuibs, frequent passage 

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