The chyme passes through the pyloric orifice of the stomach into the duodenum, the first of the small intestines, where it is mixed with two liquids, the bile, secreted by the liver, and the pancreatic juice, secreted by the pancreas, and both discharged into the duodenum to assist in the further digestion of the food. The chyme is always acid; but after it has been mixed with the bile, the acidity disappears. The characteristic constituent of the bile is a bitter-tasted substance called _picromel_, which has the property of combining with muriatic acid, and forming with it an insoluble compound. The pancreatic juice also contains a peculiar matter, to which chlorine communicates a red colour. The use of the pancreatic juice is not understood. During the passage of the chyme through the small intestines it is gradually separated into two substances; the _chyle_, which is absorbed by the lacteals, and the excrementitious matter, which is gradually protruded along the great intestines, and at last evacuated. The chyle, in animals that live on vegetable food, is semitransparent, colourless, and without smell; but in those that use animal food it is white, slightly similar to milk, with a tint of pink. When left exposed to the air it coagulates as blood does. The coagulum is _fibrin_. The liquid portion contains _albumen_, and the usual salts that exist in the blood. Thus the chyle contains two of the constituents of blood; namely, _albumen_, which perhaps may be formed in the stomach, and _fibrin_, which is formed in the small intestines. It still wants the third constituent of blood, namely, the _red_ globules. From the lacteals the chyle passes into the thoracic duct; thence into the left subclavian vein, by which it is conveyed to the heart. From the heart it passes into the lungs, during its circulation through which the _red globules_ are supposed to be formed, though of this we have no direct evidence. The lungs are the organs of _breathing_, a function so necessary to hot-blooded animals, that it cannot be suspended, even for a few minutes, without occasioning death. In general, about twenty inspirations, and as many expirations, are made in a minute. The quantity of air which the lungs of an ordinary sized man can contain, when fully distended, is about 300 cubic inches. But the quantity actually drawn in and thrown out, during ordinary inspirations and expirations, amounts to about sixteen cubic inches each time.