which are kept at pasture in summer, or which are fed liberally on roots, potatoes, pumpkins, apples, or ensilage in winter, this concentrated condition of the urine is not induced, and under such circumstances, therefore, the formation of stone is practically unknown. Nothing more need be said to show the controlling influence of dry feeding in producing gravel and of a watery ration in preventing it. Calculus in cattle is essentially a disease of winter and of such cattle as are denied succulent feed and are confined to dry fodder as their exclusive ration. While there are exceptions, they are so rare that they do not invalidate this general rule. It is true that stone in the kidney or bladder is often found in the summer or in animals feeding at the time on a more or less succulent ration, yet such masses usually date back to a former period when the animals were restricted to a dry ration. In this connection is should be noted that a great drain of water from the system by any other channel than the kidneys predisposes to the production of gravel or stone. In case of profuse diarrhea, for example, or of excessive secretion of milk, there is a corresponding diminution of the water of the blood, and as the whole quantity of the blood is thus decreased and as the urine secreted is largely influenced by the fullness of the blood vessels and the pressure exerted upon their walls from within, it follows that with this decrease of the mass of the blood and the lessening of its pressure outward there will be a corresponding decrease of urine. The waste of the tissues, however, goes on as before, and if the waste matter is passed out through the kidneys it must be in a more concentrated solution, and the more concentrated the urine the greater the danger that the solids will be deposited as small crystals or calculi.