DISEASES OF THE UEINAEY ORGANS. 141 



has formed and grown tends to dissolve out the more soluble of its 

 component parts, and thus to destroy its density and cohesion at all 

 points, and thereby to favor its complete disintegration and expulsion. 

 This explains why cattle taken from a herd on our magnesian lime- 

 stone in spring, after the long dry feeding of winter, usually furnish 

 renal calculi, while cattle from the same herd in the fall, after a sum- 

 mer's run on a succulent pasture, are almost always free from con- 

 cretions. The abundance of liquid taken in the green food and ex- 

 pelled through the kidneys and the low density or watery nature of 

 the urine have so oj^entd the texture and destroyed the density' of 

 the smaller stones and gravel that they have all been disintegrated 

 and removed. This, too, i.^ the main reason why benefit is derived 

 from a prolonged stay at mineral springs by the hmnan victims of 

 gravel. If they had swallowed the same number of quarts of pure 

 water at home and distributed it at suitable intervals over each day, 

 they would have benefited largely without a visit to the springs. 



It follows from what has been just said that a succulent diet, in- 

 cluding a large amount of water (gruels, sloppy mashes, turnips, 

 beets, potatoes, apples, pumpkins, ensilage, succulent grasses), is an 

 important factor in the relief of the milder forms of stone and gravel. 



Prevention. — Prevention of calculus especially demands this sup- 

 ply of water and watery rations on all soils and in all conditions in 

 which there is a predisposition to this disease. It must also be sought 

 by attempts to obviate all those conditions mentioned above as causa- 

 tive of the malady. Sometimes good rain water can be furnished in 

 limestone districts, but putrid or bad smelling rain water is to be 

 avoided as probably more injurious than that from the limestone. 

 Unsuccessful attempts have been made to dissolve calculi by alkaline 

 salts and mineral acids, respectively, but their failure as a remedy 

 does not necessarily condemn them as preventives. One dram of 

 caustic potash or of hydrochloric acid may be given daily in the 

 drinking water. In diametrically opposite ways these attack and 

 decompose the less soluble salts and form new ones which are more 

 soluble and therefore little disposed to precipitate in the solid form. 

 Both are beneficial as increasing the secretion of urine. In cases 

 where the diet has been too highly charged with phosphates (wheat 

 bran, etc.), these aliments must be restricted and water allowed ad 

 libitum. Where the crystals passed with the urine are the sharp 

 angidar (octahedral) ones of oxalate of lime, then the breathing 

 should be made more active by exercise, and any disease of the lungs 

 subjected to appropriate treatment. If the crystals are triangular 

 prisms of ammonia-magnesium phosphate or starlike forms with 

 feathery rays, the indications are to withhold the food or water that 

 abounds in magnesia and check the fermentation in the urine by 

 attempts to destroy its bacteria. In the latter direction plenty of 



