But even supposing that the broad outlines of physiological action are the same, nothing has hitherto been discovered in veterinary surgery respecting possible variations in the chemical processes taking place in the stomach during different gastric diseases; and it appears not improbable that in this direction causes might be discovered which veterinary practitioners have hitherto sought elsewhere. Excess or insufficiency of hydrochloric acid, and variations in the quantity of the organic acids, play so important a part in the theory of gastric pathology in man, that it is scarcely surprising to find similar ideas recurring in the pathology of domestic animals. The correctness of these views remains to be proved; and without wishing actually to classify dyspeptic conditions as in man, we may assert that diseases described under other names stand in direct relation to variations in the gastric secretion or to disturbance of gastric movements—_e.g._, simple chronic tympanites, which, without a doubt, is often a neuro-motor dyspepsia. The classification we shall adopt in studying the diseases of the gastric compartments is, therefore, extremely simple. In the first series we shall consider sudden, accidental, and temporary forms of indigestion, and in the second series, acute or chronic forms of gastric inflammation. INDIGESTION. GASEOUS INDIGESTION. Gaseous indigestion, also described as indigestion of the rumen, is characterised by the rapid accumulation of gases (chiefly carbon dioxide, carbon monoxide, and marsh gas), due to fermentation in the upper part of the rumen. It is common in oxen and sheep, and has received the names of mephitic indigestion, acute tympanites, meteorism, etc. It occurs during or immediately after feeding. =Causation.= Numerous causes have been invoked to explain the sudden occurrence of gaseous indigestion. The most important is the particular condition of the animal at the moment when it has been attacked. For if external influences alone were responsible, there is no reason why all the animals of a given herd or flock, or of a particular stable, which are under similar conditions as regards feeding, etc., should not be affected in the same way. That the external causes cited (cold, excessive heat, stormy weather, etc.) may affect different animals differently and unfavourably is beyond doubt. But the temporary morbid condition of the animal itself is the essential condition to the development of indigestion.