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plates, which are quite transparent. When retained within the blood, it gives rise to the condition of cholesteræmia, attended with severe nervous symptoms. It is given off in the feces under the form of stercorin.

The coloring matters which give the tints to the bile are biliverdin and bilirubin, and are probably derived from the coloring matter of the blood. Their presence in any fluid can be recognized by adding to it nitric acid containing nitrous acid, when a play of colors is observed, beginning with green, blue, violet, red, and yellow.

The Bile is both a secretion and an excretion ; it is constantly being formed and discharged by the hepatic ducts into the gall bladder, in which it is stored up, during the intervals of digestion. As soon as food enters the intestines it is poured out abundantly by the contraction of the walls of the gall bladder.

The amount secreted in 24 hours is about 2%2 pounds.

Functions of the Bile.—(1) It assists in the emulsification of the fats and promotes their absorption. (2) It tends to prevent putrefactive changes in the food. (3) It stimulates the secretions of the intestinal glands, and excites the normal peristaltic movement of the bowels.

The digested food, the chyme, is a grayish, pultaceous mass, but as it passes through the intestines it becomes yellow, from admixture with the bile. It is propelled onward by vermicular motion, by the contraction of the circular and longitudinal muscular fibers.

As the Digested Food passes through the intestines, the nutritious matters are absorbed into the blood, and the residue enters the large intestine.

The Feces consist chiefly of indigestible matters, excretin, stercorin, and salts, varying in amount from 4 to 7 ozs. in 24 hours.

Defecation is the voluntary act of extruding the feces from the body, accomplished by a relaxation of the sphincter muscle, the contraction of the walls of the rectum, assisted by the abdominal muscles.

The Gases contained in the stomach and small intestine are oxygen, nitrogen, hydrogen, and carbonic acid. In the large intestine, carbonic acid, sulphuretted and carburetted hydrogen. They are introduced with the food, and also developed by chemical changes in the alimentary canal. They distend the intestines, aid capillary circulation, and tend to prevent pressure.

ABSORPTION. The term absorption is applied to the passage or transference of material into the blood from the tissues, from the serous cavities, and from the mucous surfaces of the body. The most important of these surfaces, especially in its relation to the formation of the blood, is the mucous surface of the alimentary canal; for it is from this organ that new materials are derived which maintain the quality and quantity of the blood. The absorption of materials from the interstices of the tissues is to be regarded rather as a return to the blood of liquid nutritive material which has escaped from the blood vessels for nutritive purposes, and which, if not returned, would lead to an accumulation of such fluid and the development of dropsical conditions.

The anatomical mechanisms involved in the absorptive process are, primarily, the lymph spaces, the lymph capillaries and blood capillaries ; secondarily, the lymphatic vessels and larger blood-vessels.

Lymph Spaces, Lymph Capillaries, Blood Capillaries.-Everywhere throughout the body, in the intervals of connective tissue bundles, and in the interstices of the several structures of which an organ is comi. posed, are found spaces of irregular shape and size, determined largely by the nature of the organ in which they are found, which have been termed lymph spaces or lacuna, from the fact that during the living condition they are continually receiving the lymph which has escaped from the bloodvessels throughout the body. In addition to the connective tissue lymph spaces, various observers have described special lymph spaces in the testicle, kidney, liver, thymus gland, and spleen; in all secreting glands between the basement membrane and blood vessels; around blood-vessels (perivascular spaces) and around nerves. The serous cavities of the body, peritoneal, pleural, pericardial, etc., may also be regarded as lymph spaces, which are in direct communication by open mouths or stomata with the lymphatic capillaries. This method of communication is not only true of serous membranes, but to some extent also of mucous membranes. The cylindrical sheaths and endothelial cells surrounding the brain, spinal cord, and nerves can also be looked upon as lymph spaces in connection with lymph capillaries.

The lymphatic capillaries, in which the lymphatic vessels proper take their origin, are arranged in the form of plexuses of quite irregular shape. In most situations they are intimately interwoven with the blood-vessels, from which, however, they can be readily distinguished by their larger

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ABSORPTION. The term absorption is applied to the passage or transference of material into the blood from the tissues, from the serous cavities, and from the mucous surfaces of the body. The most important of these surfaces, especially in its relation to the formation of the blood, is the mucous surface of the alimentary canal; for it is from this organ that new materials are derived which maintain the quality and quantity of the blood. The absorption of materials from the interstices of the tissues is to be regarded rather as a return to the blood of liquid nutritive material which has escaped from the blood-vessels for nutritive purposes, and which, if not returned, would lead to an accumulation of such fluid and the development of dropsical conditions.

The anatomical mechanisms involved in the absorptive process are, primarily, the lymph spaces, the lymph capillaries and blood capillaries ; secondarily, the lymphatic vessels and larger blood-vessels.

Lymph Spaces, Lymph Capillaries, Blood Capillaries.—Everywhere throughout the body, in the intervals of connective tissue bundles, and in the interstices of the several structures of which an organ is comiposed, are found spaces of irregular shape and size, determined largely by the nature of the organ in which they are found, which have been termed lymph spaces or lacuna, from the fact that during the living condition they are continually receiving the lymph which has escaped from the bloodvessels throughout the body. In addition to the connective tissue lymph spaces, various observers have described special lymph spaces in the testicle, kidney, liver, thymus gland, and spleen; in all secreting glands between the basement membrane and blood vessels; around blood-vessels (perivascular spaces) and around nerves. The serous cavities of the body, peritoneal, pleural, pericardial, etc., may also be regarded as lymph spaces, which are in direct communication by open mouths or stomata with the lymphatic capillaries. This method of communication is not only true of serous membranes, but to some extent also of mucous membranes. The cylindrical sheaths and endothelial cells surrounding the brain, spinal cord, and nerves can also be looked upon as lymph spaces in connection with lymph capillaries.

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