By absorption we transfer material into the blood from the tissues, the serous cavities, and the mucous surfaces. The mechanism employed is, first, the lymph spaces, the lymph capillaries, and the blood capillaries; second, the lymphatic vessels and larger blood-vessels. The lymphatic vessels take their origin in the lymph capillaries. These lymph capillaries are interwoven with the blood-vessels. They are valveless. They anastomose freely with one another and communicate with the lymph spaces and the lymphatic vessels. They collect the lymph which may have escaped from the blood-vessels and transmit it to the regular lymphatic vessels. The blood capillaries are also active in absorption and also allow the escape through their delicate walls of liquid nutritive portions of the blood. They are probably more active than the lymph capillaries in absorbing the products of digestion. The lymphatic vessels pass through the lymphatic glands. In the small intestines they are called lacteals. They are guarded by semilunar valves opening towards the larger vessels. The lymphatic glands complete the lymphatic system. In them are lymph channels. Through these channels the lymph is poured by the lymphatic vessels and is transmitted onward. Chyle is the product of intestinal digestion, found in the lacteals and thoracic duct as a milky-looking fluid containing corpuscles, fat globules, fibrin etc.

The agents most active in absorption are the blood-vessels of the digestive canal, particularly those going to form the great portal vein. Again the lymphatics coming from the small intestines converge to empty into the thoracic duct. The products of digestion get into the general circulation by two routes. First, the water, peptones, glucose, and salts, after passing into the lymph spaces of the villi, pass through the walls of the capillary blood-vessels, then into the blood, and are carried to the liver by the vessels forming the portal vein. Coming out of the liver, they pass to the vena cava by the hepatic vein. The fat emulsion enters the lymph capillary, and it contracts and forces the contents into the lacteals, and then into the thoracic duct, and finally into the circulation at the junction of the internal jugular and subclavian veins on the left side. Lymph is absorbed into the system for its many uses. When in excess, it is reabsorbed and reused.

Lymph is the fluid of the lymphatics. It is alkaline and much like blood in its chemical composition. It contains leucocytes and fatty matter. It contains, water, 95.536; proteids, 1.320; extractives, 1.559; fatty matters, a trace; salts, 0.585.

Chyle, as before shown, is the product of intestinal digestion. It is found in the lacteals and thoracic duct as a milky-looking fluid containing corpuscles, fat globules, fibrin, proteids, and salts. It contains, water, 902.37; albumin, 35.16; fibrin, 3.70; extractives, 15.65; fatty matters, 36.01; salts, 7.11.

Blood consists of two portions, the liquor sanguinis, or plasma, and the corpuscles, white and red. Haemoglobin is the coloring matter, and is composed of C, O, H, N, S, and iron. The function of the red corpuscles is to absorb oxygen and carry it to the tissues. The red corpuscles far outnumber the white corpuscles. The white corpuscles are termed amoeboid, because they have the power of movement and of changing their shape. They can move from place to place and adhere to the surface of the vessels, whilst the red corpuscles rush through the centre of the stream. The white corpuscles are identical with leucocytes and are found in milk, lymph, chyle, and other fluids. The white corpuscles are of the greatest importance in the economy. They are the body scavengers, as they prey upon and destroy pathogenic and other germs and tend greatly to make life possible. In giving this resume of digestion I acknowledge the help I have obtained from Prof. Brubaker's "Compend of Physiology."