_Real Causes of Rot._ Everything that has a tendency to weaken the animal, will be more or less liable to lead to rot. Exposure to cold and wet, mishaps at lambing time, food bad in quality or deficient in quantity, and over-driving, will all predispose the constitution to the deposition of tubercles. It is from the causes being in this way common to the whole flock, that contagious properties have been ascribed to rot, it having been observed, from the time of Virgil, to break out in many animals at once.[38] [38] "Nor oftener are the floods disturb'd with wind Than sheep with rots; nor doth the sickness find One to destroy, but suddenly doth fall On root and branch, stock and original." _Virgil's Georgics_, Lib. III. The reason of so many different things having, from first to last, been reckoned capable of producing this disease, appears to lie in the known fact, that if a sheep be exposed to any of the above depressing agents, rot, if the animal be as yet untainted, will not, at the moment, shew itself; but a chain of morbid actions will in all probability then commence, and, being beyond the ken of ordinary observers, will pass unheeded, till some slight mismanagement in food or shelter, hastens their progress, and renders them apparent to the plainest understanding. The final symptoms of rot may thus occur on any kind of pasture, and the scene of the catastrophe will incur a stigma which ought to be attached to herbage which the sheep have consumed at some distant place or date. Bad food is justly regarded as one of the most common causes of rot, and ranks, in my estimation, next to cold and wet, in its power of producing it. I shall only remark, on this point, that of all the food on which sheep can possibly be kept, none is known to act so deleteriously as grass which has sprouted quickly. Rot is well known to occur most frequently on land which has been irrigated during summer, for at this season any excess of moisture is peculiarly injurious to the economy of a plant. When plants by heat and moisture are stimulated to increased exertion on a poor soil, they acquire bulk without having it in their power to obtain at the same time those saline matters which constitute a healthy plant, becoming in fact, to the eye of an inexperienced person, thriving vegetables, while to the palate they prove wersh and watery.