The vessels by which the process of absorption is carried on are called absorbents. The story, briefly told, is this: certain food materials that have been prepared to enter the blood, filter through the mucous membrane of the intestinal canal, and also the thin walls of minute blood-vessels and lymphatics, and are carried by these to larger vessels, and at last reach the heart, thence to be distributed to the tissues. 155. Absorption from the Mouth and Stomach. The lining of the mouth and œsophagus is not well adapted for absorption. That this does occur is shown by the fact that certain poisonous chemicals, like cyanide of potash, if kept in the mouth for a few moments will cause death. While we are chewing and swallowing our food, no doubt a certain amount of water and common salt, together with sugar which has been changed from starch by the action of the saliva, gains entrance to the blood. In the stomach, however, absorption takes place with great activity. The semi-liquid food is separated from the enormous supply of blood-vessels in the mucous membrane only by a thin porous partition. There is, therefore, nothing to prevent the exchange taking place between the blood and the food. Water, along with any substances in the food that have become dissolved, will pass through the partition and enter the blood-current. Thus it is that a certain amount of starch that has been changed into sugar, of salts in solution, of proteids converted into peptones, is taken up directly by the blood-vessels of the stomach. 156. Absorption by the Intestines. Absorption by the intestines is a most active and complicated process. The stomach is really an organ more for the digestion than the absorption of food, while the small intestines are especially constructed for absorption. In fact, the greatest part of absorption is accomplished by the small intestines. They have not only a very large area of absorbing surface, but also structures especially adapted to do this work. 157. The Lacteals. We have learned in Section 144 that the mucous lining of the small intestines is crowded with millions of little appendages called villi, meaning “tufts of hair.” These are only about 1/30 of an inch long, and a dime will cover more than five hundred of them. Each villus contains a loop of blood-vessels, and another vessel, the lacteal, so called from the Latin word _lac_, milk, because of the milky appearance of the fluid it contains. The villi are adapted especially for the absorption of fat. They dip like the tiniest fingers into the chyle, and the minute particles of fat pass through their cellular covering and gain entrance to the lacteals. The milky material sucked up by the lacteals is not in a proper condition to be poured at once into the blood current. It is, as it were, in too crude a state, and needs some special preparation.