KENAL CALCULI. 57 



from water, and are especially found in the calculi of cattle 

 and sheep. 



It is in animals living partially or entirely on animal food 

 that we find the ammonio-phosphate of magnesia, and the 

 phosphate of lime building up concretions in the urinary 

 apparatus. 



To favour the formation of urinary calculi, the urine 

 must be alkaline, and the materials are most readily de- 

 posited in conditions in which they are difficult of solution, or 

 easily crystallized. A nucleus usually exists, and this may 

 be simply composed of mucus or saline materials accidentally 

 solidified, or foreign substances introduced into the urinary 

 organs. In female animals, bits of stick, straw, wire, stone, 

 &c., have been found to constitute such nuclei. 



Urinary calculi are classified, according to their position, 

 into (a) renal, (6) ureteral, (c) vesical, (d) urethral, (e) pre- 

 putial ; and lastly, (f) the deposit in the form of gravel. 



(a) Renal calculi are lodged in the substance of one or 

 both kidneys. They are usually single and large in the 

 horse, and occur more frequently in this animal than in any 

 other. They are of a brownish white, brown, and sometimes 

 bluish colour ; of irregular, ovoid, or nearly spherical shape ; 

 often nodulated, and always more or less rough, owing to 

 the irregular deposition of the carbonate of lime. They are 

 lodged in cysts, with firm parietes, and containing a quantity 

 of thick urine. They have a strong urinous odour when first 

 removed from the kidney. On cutting them in halves, the 

 materials are found deposited in layers, which are more or 

 less distinctly seen. In cattle calculi are found with a surface 

 of a bright metallic lustre. These calculi occur in consider- 

 able numbers, and vary in size from a millet seed to a pea. 



Fiirstenberg furnishes us with several analyses of renal 

 calculi in different animals. 



