It is the only gastric compartment which cannot be examined, although when impacted it may be felt on the right side. =Abomasum.= The abomasum is lodged in the lower part of the right flank under the circle of the hypochondrium. It extends obliquely from below, upwards from the sub-ensiform to the sublumbar region. The smaller curvature is turned towards the rumen on the left side; the larger curvature is in contact with the abdominal wall. In spite of what has so often been stated by those who have never seen it, the abomasum can be examined and is accessible along the circle of the hypochondrium. In adults useful information can rarely be obtained by inspection; but in sucking calves the abomasum, if distended by indigestion, gastro-enteritis, etc., sometimes appears prominently in the right abdominal region. Palpation with the fingers or with the fist will detect exaggerated sensibility, irritation, inflammation, or distension. Percussion and auscultation furnish no very precise information. The information obtained by the above-described examination of the stomach is in practice amplified by a search for certain symptoms which are usually easy to detect. They comprise: (_a_) Suppression or irregularity of rumination. This very important symptom suggests the degree of gravity of the digestive disturbance, and to some extent the gravity of the general condition. Suppressed rumination is a common symptom in many diseases, some of which are purely digestive, though all are not. It is, however, a grave sign in most cases. (_b_) Eructation, which is usually frequent, may be regarded as normal provided the exhaled gas preserves the fresh odour of grass or of the food swallowed, like brewers’ grains, turnips, etc. Sometimes the gas is sour, acid, fœtid, or putrid, all of which conditions indicate disease. (_c_) Yawning is not common. It becomes frequent and attracts attention in certain abnormal conditions; in others, again, it may be completely suppressed. (_d_) Nausea and vomiting are rare. Vomiting is commoner in calves, and results from inability to digest the milk, or simply to over-distension of the abomasum. The matter vomited by adults usually consists of partly masticated food, and is derived from the rumen; while the contents of the abomasum are occasionally rejected, in which case the material is of pulpy consistence and has an acid smell. (_e_) Digestive disturbance is sometimes accompanied by various modifications in the breathing, such as immobilisation of the hypochondriac region and of the diaphragm; abnormal sensibility and reflex coughing on palpation, and, in inflammation of the reticulum due to foreign bodies, costal respiration. [Illustration: $1] It is by methodically observing, grouping, and classifying the symptoms presented that one is enabled to detect the links connecting them.