The cleaning of corn is a point of stable management to which special attention should be paid; because foreign substances in the food are apt to give rise not only to ordinary digestive disturbances, but also to the formation in the intestines, of calculi and concretions, which are very often fatal to their bearer. "Experience amply proves that the presence in the horse's food, of indigestible particles, especially if they be of an irritating nature, is a fertile cause of calculus. The frequency of this complaint in the stables of many large firms has been greatly diminished by the adoption of means for the removal of such possible nuclei. One of the best preventives is the use of an automatic separator provided with magnets, which attract and thus remove all particles of iron and steel from the corn passed over them. In small stables, the careful use of a sieve is imperative. Rogerson has pointed out that in foreign corn, among other sources of danger, are to be found numbers of nails and heads of nails which are employed to tack down the canvas that lines the holds of vessels which carry the corn in bulk. . . . Hunting mentions that the indiarubber ring of a mineral water bottle formed the nucleus of a calculus which he examined on one occasion. . . . There is some evidence to show that forage which contains a quantity of the hairs and husks of oats, or meal dust, is liable to give rise to intestinal concretions, which are hardly ever found among animals whose food is carefully looked after" ( Veterinary Notes for Horse-Owners). See page 158.