436 DISEASES OF DIGESTION. 



It may be surmised that the presence of such an object sets up, in 

 the first instance, irritation of the mucous membrane of the bowel, 

 with the result of its becoming surrounded" with mucus, to which 

 other undigested objects, passing by, would be liable to adhere. 

 Or the irritation might cause the precipitation from the dissolved 

 food of earthy salts. The tendency to calculus depends on the 

 fact of indigestible and irritating substances being taken into the 

 stomach. In ojje case the indiarubber ring -of a mineral water 

 bottle formed the nucleus of a calculus. 



I have shown in " Stable Management and Exercise " that dry 

 bran is an admirable food for horses, and is much more digestible 

 than oats. Wet bran (bran mash) is more a medicine (a laxative) 

 than a food. 



From an examination of a phosphatic calculus, we cannot help 

 being struck by the fact that the deposition of its earthy con- 

 stituents must have taken place from a fluid which had held them 

 in solution. Consumption of food rich in phosphates (like bran 

 and maize) may therefore be regarded to be a predisposing, though 

 not an exciting, cause. Another predisposing cause might be a 

 condition of the digestion, in which these earthy salts would be 

 more liable to be deposited from the alimentary fluid, than in a 

 state of health. 



" True intestinal calculi consist principally of a deposit of an ammonio- 

 magnesium phosphate (90 per cent, according to Fiirstenberg) with which 

 are found phosphate of lime, phosphate of magnesia, silica, certain chlorides, 

 and traces of iron and organic matter (mucus, epithelium and alimentary 

 substances). They are formed from the phosphate of magnesia of the bran, 

 which is rich in it. This phosphate of magnesia unites with the ammonia- 

 cal compounds which exist in the contents of the bowels. These compounds 

 are derived from the atmosphere of the stable, and are introduced into the 

 digestive tube along with the drinking water. An insoluble basic-phosphate 

 is thus formed in the intestines. The starting-point of the precipitation is 

 generally a foreign body, such as a grain of sand or an oat, around which 

 layers of basic phosphate are contmually deposited" (Friedberger and 

 Frohiwr). The foregoing remarks on the formation of a calculus naturally 

 suggest the inference that the more loaded with ammonia the air of a 

 stable is, the more likely will calculi be formed in the intestines of horses 

 living in such a stable. Bearing on this subject, there are two facts which 

 deserve notice. First : Continental veterinary authorities are unanimous 

 in saying that the feeding of horses on bran is a fertile cause of calculi in 

 the intestines of such animals. Second : For the last thirty-five years 1 

 have fed horses on bran combined with oats or other grain, and have known 

 thousands of other horses similarly fed ; but have not met with a single 

 case of calculus from such regimen, which was given, however, under good 

 sanitary conditions. I therefore conclude that there is no danger of in- 

 testinal calculi from feeding_ horses on bran, if the air of the stable is 

 practically free from ammonia. 



There is some evidence to show that forage containing a 

 quantity of the hairs and husks of oats, or meal dust, is apt to 



