Of the internal secreting organs, the _liver_ is the largest. Its chief office is to secrete from the blood all matter not properly supplied with oxygen. For this purpose, a set of veins carries the blood of all the lower intestines to the liver, where the imperfectly oxidized matter is drawn off in the form of _bile_, and accumulated in a reservoir called the _gall-bladder_. Thence it passes to the place where the smaller intestines receive the food from the stomach, and there it mixes with this food. Then it passes through the long intestines, and is thrown out of the body through the rectum. This shows how it is, that want of pure and cool air and exercise causes excess of bile, from lack of oxygen. The liver also has arterial blood sent to nourish it, and corresponding veins to return this blood to the heart. So there are two sets of blood-vessels for the liver--one to secrete the bile, and the other to nourish the organ itself. The kidneys secrete from the arteries that pass, through them all excess of water in the blood, and certain injurious substances. These are carried through small tubes to the bladder, and thence thrown out of the body. The _pancreas_, a whitish gland, situated in the abdomen below the stomach, secretes from the arteries that pass through it the pancreatic juice, which unites with the bile from the liver, in preparing the food for nourishing the body. There are certain little glands near the eyes that secrete the tears, and others near the mouth that secrete the saliva, or spittle. These organs all have arteries sent to them to nourish them, and also veins to carry away the impure blood. At the same time, they secrete from the arterial blood the peculiar fluid which it is their office to supply. All the food that passes through the lower intestines which is not drawn off by the lacteals or by some of these secreting organs, passes from the body through a passage called the rectum. Learned men have made very curious experiments; to ascertain how much the several organs throw out of the body, It is found that the skin throws off five out of eight pounds of the food and drink, or probably about three or four pounds a day. The lungs throw off one quarter as much as the skin, or about a pound a day. The remainder is carried off by the kidneys and lower intestines. There is such a sympathy and connection between all the organs of the body, that when one of them is unable to work, the others perform the office of the feeble one. Thus, if the skin has its perspiration-tubes closed up by a chill, then all the poisonous matter that would have been thrown out through them must be emptied out either by the lungs, kidneys, or bowels.