Perhaps the best internal treatment consists in administering purgatives such as hyposulphite or sulphate of soda or sulphate of magnesia, in doses of 10 to 20 ounces, according to the animal’s size, or, in the case of pregnant animals, in small frequently repeated doses. These check fermentation, and so arrest the evolution of gas, whilst by their purgative properties they excite contraction of the gastric reservoirs and cause eructation. None of these methods of treatment, therefore, should be used exclusively, but all may be utilised as auxiliaries to mechanical or surgical measures, and all should be preceded by the use of the probang and puncture of the rumen. The first of these operations, the technique of which scarcely requires description, is often of little value; for the solids and liquid contents of the rumen being permeated with gases, rise as a fermenting mass into the upper portions of the rumen, and continually obstruct the open end of the catheter, so that very little gas escapes. Puncture of the rumen is much more effective and easier to perform. The owner himself often operates with an ordinary pocket knife, sometimes introducing a couple of fingers or a short length of elder-wood tube into the wound thus produced. The incision should be made at one stroke, for any hesitation may cause the wall of the abdomen to recede from the rumen, which lies immediately below. Should gas escape under the skin, emphysema, which often extends to the loins and along the quarters, may be produced, and may be followed by diffuse subcutaneous suppuration, resulting from pyogenic germs entering the subcutaneous tissue. Large quantities of gas escape from the puncture, sometimes with such force as to drive out the canula. The flow of gas then ceases. In other cases the tube becomes blocked; because, as the pressure within the rumen diminishes, the gases dissolved or mixed with the partially digested food are freed, and the whole contents of the rumen become converted into an aerated, bubbling mass. Liquid or semi-liquid materials may be ejected to some distance, or may pass between the skin and the muscles, or between the walls of the rumen and the abdomen, producing various complications, like necrosis, abscess formation, etc. Such accidents can be avoided by exercising firm pressure with the fingers on the tissues surrounding the canula. Even when the rumen has resumed its normal size recovery is not certain, and may not occur for several hours, or even several days, afterwards. The patients should therefore be kept under observation for some time, and it is usually best to leave the canula in place for one or two days, and to put the animal on low diet. Necrosis of aponeurotic tissues, fistula formation, and local peritonitis only occur if the instrument is dirty or is introduced in a wrong direction. IMPACTION OF THE RUMEN. INDIGESTION AS A RESULT OF OVER-EATING.