Attempts have also been made to divide the obstructing body directly without previous incision and without isolating the œsophagus. It is much more difficult, for the least movement of the patient changes the relationships of the superposed layers and introduces obstacles to the manipulation of the blunt-pointed tenotome which is employed. More success often attends attempts to puncture the object with a fine trocar. RUPTURES AND PERFORATIONS OF THE ŒSOPHAGUS. =Causation.= Wounds of the œsophagus caused by external violence are rare, or at least secondary; lacerations produced from within, on the contrary, as a result of clumsy manipulation are relatively frequent. They may extend throughout the length of the tube, but in a far greater number of cases are found near the entrance to the stomach at the point where the œsophagus turns towards the left. The passage of the œsophageal sound or probang is apt to exaggerate this curvature, and if pushed violently the instrument may produce first a flexure, then a partial rupture or even a perforation of the tube. In other cases a rough, irregular, infected foreign body may when swallowed penetrate the wall and cause inflammation, necrosis and perforation of the œsophagus. =The symptoms= are always very grave, and of rapid development. They consist in local œdematous swelling, sero-sanguineous infiltration at the entrance to the chest, in the pretracheal region and along the jugular furrows. The pneumo-gastric and inferior laryngeal nerves being compressed, dyspnœa results. If the œsophagus is perforated in the thoracic cavity septic pleurisy at once sets in. =Diagnosis.= The diagnosis is easy, provided the history point to perforation of the œsophagus. =The prognosis= is fatal whenever the perforation is within the thorax. It is sometimes possible to intervene in cases of perforation in the cervical region, but from the economic standpoint such intervention is of little value. CHAPTER IV. DEPRAVED APPETITE—PICA—THE LICKING HABIT. Depraved appetite, causing animals to swallow bodies which cannot properly be described as food, is frequent. The condition is commonest in adult animals of the bovine species, in calves and in lambs. The consequences are sometimes very serious, so that although depraved appetite does not represent a well-defined morbid entity, it is important to be in a position to remedy it. Depraved appetite does not appear under the same conditions in young and in old animals. In adults it often results from faulty feeding, or from some wasting disease which develops insidiously, or remains unrecognised; in young animals it is the result of insufficient nourishment. Roloff & Röll hold that pica is the first symptom of osteomalacia (which see). DEPRAVED APPETITE IN THE OX.