We cannot prove whether the forms said to be due in man to excess of hydrochloric acid and insufficiency of hydrochloric acid really occur or are well defined in domestic animals: nor are we better informed as to the exact part played by the organic acid of fermentation (lactic, butyric, acetic acid, etc.); but the most complete investigations which have yet been made justify our supposing there is some parallel. Moussu described primary ulcerative gastritis in 1895; and as this form is almost certainly associated with excess of pepsin, the occurrence of an excess of hydrochloric acid also seems possible, the more so as the symptoms noted resemble the general symptoms of that condition—preservation of appetite and of the motor power of the rumen, accumulation of food in the rumen as a consequence of reflex intolerance of the abomasum, constipation, and vomiting. In addition to these two morbid conditions, a third occurs with some frequency. It is characterised by chronic tympanites, alimentary diarrhœa (the food being badly digested), and progressive wasting. This condition seems due to an insufficiency of hydrochloric acid, brought about by chronic gastritis, the epithelial cells of the mucous membrane appearing incapable of producing sufficient hydrochloric acid for digestion. =Diagnosis.= In the present state of our knowledge regarding digestion in ruminants the precise diagnosis of these pathological conditions must always remain difficult; but it is indisputable that with the above grouping of symptoms we are more likely to succeed than by confining ourselves to the diagnosis formerly common, viz., that of chronic tympanites or chronic indigestion. The difference between primary and secondary dyspepsia should always be borne in mind, and careful examination will often reveal the special condition which has served as the point of departure for gastric disturbance. Thus generalised tuberculosis, or tuberculosis of the liver or mediastinum, should always be sought for, and the possible existence of such conditions of the liver as echinococcosis, cancer of the bile ducts, tumours, etc., and diseases of the kidneys should be borne in mind. The influence of gestation, which so frequently causes gastric disturbance complicated with albuminuria, should never be overlooked, and in these secondary forms of dyspepsia the determining cause, and not the objective symptoms should receive chief attention. =Prognosis.= The prognosis of secondary forms of dyspepsia varies with the gravity of the primary disease. The prognosis of primary dyspeptic conditions varies greatly, and that state in which hydrochloric acid is too sparingly secreted is certainly the gravest.