Meat consists of muscle-fibres supported by connective tissue. In the stomach the gelatiniferous connective tissue is dissolved, setting the fibres free. Further, the fibres being surrounded by a membrane of the same nature—sarcolemma—this is removed; and although it may be hardly justifiable to speak of “Krause’s membranes” (_cf._ Fig. 10) as gelatiniferous septa, the fibres are certainly composed of segments—Bowman’s discs, sarcous elements—into which they break up under the action of gastric juice. As a result, meat-fibre is reduced to a finely divided granular condition. The capacity of gastric juice for dissolving collagen (the substance of which connective tissue is composed) may be regarded as its most characteristic, as it is one of its most valuable, properties. Collagen, when boiled or acted on by acids, takes water into its molecule, becoming gelatin. Under the influence of gastric juice gelatin is rapidly hydrolysed into diffusible gelatin-peptone. Pancreatic juice is unable to act upon collagen, unless it has been previously boiled, or swollen by the action of dilute acids. Fat is composed of vesicles of oil supported by connective tissue. Gastric juice, by dissolving the connective tissue and the collagenous walls of the vesicles, sets the oil free. The oil, even though it be as firm as suet when cold, is liquid, or almost liquid, at the temperature of the body. Thus, with the exception of raw vegetables, the hard fibre of cooked vegetables, elastic tissue of meat, and a few other indigestible substances, the meal is reduced in the stomach to a cream-coloured, fatty, strongly acid “chyme.” In this condition it enters the duodenum, where it at once comes into contact with an alkaline secretion. The passage of acid chyme down this portion of the canal provokes the discharge of gushes of bile and pancreatic juice. By precipitating partially digested proteins and “acid-albumin” bile renders the mixture thicker and sticky. It colours it yellowish-brown. Under the influence of pancreatic juice the remaining proteins and proteoses are rapidly converted into peptones, some of which are shaken down by the violent action of erepsin into simpler bodies, such as leucin and tyrosin, etc. The chyme becomes alkaline, grey, and thin. All undigested starch is changed into maltose, and this into dextrose. Cane-sugar is converted into dextrose and levulose. These sugars are absorbed into the blood. Milk-sugar, if not converted into lactic acid, remains as lactose (C₁₂H₂₂O₁₁), in which condition it is absorbed without “inversion.” Fats are split by a ferment of the pancreatic juice into fatty acid and glycerin; some of the fatty acid combines with alkali to form soap, but of this we shall have more to say later on.