=History.= Having been described by Vegetius, the disease was again observed about 1650 in Norway where it was treated by the administration of crushed bones. It is fairly frequent in some parts of Germany and Belgium. In France it was studied in 1825 by Roux, and in 1846 by Dupont, but Zundel in 1870 was the first who gave a good description of it, founded partly on the authority of German authors and partly on observations made by himself in the Valley of the Lower Rhine. Since that time it has successively been reported in the Yonne by Thierry, in the Nièvre by Vernant, in the Aube by Collard and Henriot (1893), in the Indre by Cantiget, as well as in La Vendée by Tapon in 1893. In that and the succeeding year Moussu also saw numerous cases in the districts of Indre-et-Loire, Loire-et-Cher, Berry, Sologne, and in some parts of Beauce. =Symptoms.= The first symptoms are difficult to detect and interpret, especially at the commencement of an outbreak and in parts where the disease is rare they may lead to confusion and errors in diagnosis. On the other hand, in regions where the disease is common the practitioner will be able to form his diagnosis from the appearance of the first signs. To render clear the mode in which the symptoms develop we may divide the progress of the disease into four phases, though this grouping is somewhat arbitrary. =1. The initial phase= is not well marked, and is announced by digestive disturbance and by wasting. The former of these symptoms may be referred to some other cause, but consists in irregularity, diminution and sometimes perversion of the appetite. These earlier signs are soon followed by loss of spirits, and some interference with movement, but the symptoms only become of importance or attain their full development when the animals remain lying for a long period in the stable. [Illustration: $1] =2. The second phase= is characterised by more precise signs, which become almost pathognomonic. Difficulty in rising is added to the already existing tendency to remain lying, and to the interference with movement. When lying down the patient no longer responds to the trifling stimulus, which a healthy animal needs to cause it to rise. It remains languid and apparently lazy, though in reality it experiences pain and difficulty on attempting to get up. The least muscular effort when lying down often causes it to moan, as do efforts to change its position or to walk. Even when standing still, it may appear to be in pain, and patients often assume a position similar to that of a horse suffering from laminitis. At the end of this second phase, swellings appear, due to synovitis or arthritis of the extremities, synovitis of the sesamoid or navicular sheaths or to inter-phalangeal arthritis or arthritis of the fetlock joint. Weakness becomes marked, and the appetite is very irregular. Secretion of milk diminishes or ceases and abortion is not uncommon.