The feet of sheep are organized in such a manner as to be capable, when in a healthy state, of eliminating from the system a large amount of worn-out materials--excrementitious matter, which, if retained in the system, would be injurious. The direct application of cold tends to contract the mouths of excrementitious vessels, and the morbid matter accumulates. This is not all. There are in the system numerous outlets,--for example, the kidneys, lungs, surface, feet, &c. The health of the animal depends on all these functions being duly performed. If a certain function be interrupted for any length of time, it is sure to derange the system. Diseases of the feet are very common in wet situations, and are a source of great loss to the farming community. Hence it becomes a matter of great importance to know how to manage them so as to prevent diseases of the feet. Professor Simonds says, "No malady was probably so much feared by the agriculturist as the rot; and with reason, for it was most destructive to his hopes. It was commonly believed to be incurable, and therefore it was all important to inquire into the causes which gave rise to it. Some pastures were notorious for rotting sheep; on other lands, sheep, under all ordinary circumstances, were pastured with impunity; but, as a broad principle, it might be laid down that an excess of moisture is prejudicial to the health of the animal. Sheep, by nature, are not only erratic animals, wandering over a large space of ground, but are also inhabitants of arid districts. The skill of man has increased and improved the breed, and has naturalized the animal in moist and temperate climates. But, nevertheless, circumstances now and then take place which show that its nature is not entirely changed; thus, a wet season occurs, the animals are exposed to the debilitating effects of moisture, and the rot spreads among them to a fearful extent. The malady is not confined to England or to Europe; it is found in Asia and Africa, and occurs also in Egypt on the receding of the waters of the Nile.