I. - I. Starchy foods are converted into glucose in the mouth by the action of the saliva, and in the duodenum by the action of the pancreatic juice.

2. Albuminous foods are converted into soluble albu-moses or peptones by the action of the pepsine of the gastric juice acting in an acid medium, and by the trypsine of the pancreatic juice acting in an alkaline or neutral medium.

3. Fats are emulsified in the intestines by the action of the pancreatic juice, the bile, and the intestinal juice.

II. - 1. Albumose is absorbed by the venous radicles of the stomach and intestines, and carried by the portal vein to the liver.

2. Glucose is absorbed by the capillaries of the villi, and carried by the mesenteric veins to the portal vein, and thence direct to the liver.

3. Emulsified fats are absorbed by the lacteals, and are carried by the thoracic duct to the left jugular vein.

III. - 1. Albumose is converted by the liver into albumen, and is present in the blood in the form of blood serum and fibrine.

2. Glucose is converted by the action of the liver into glycogen, and is stored there for use in the economy.

3. Fats are burnt off in the lungs and in the tissues in the production of body heat. Fat is also stored up in the tissues for future use.

The various digestive juices are re-absorbed during and after the process of digestion.

The excretory products of digestion are the bile, excreted by the liver; the urine, containing urea, excreted by the kidneys; and the faeces, containing the indigestible and undigested remnants of food, broken-down cells, masses of bacilli which flourish in the intestine, and the colouring matters of the bile.

Any abnormal divergence from the long and complicated process of digestion will give rise to many conditions of ill-health and disease, to dyspepsia, gout, diabetes, etc.