undergoes a process which we will speak of when we reach the subject of the liver. The chyle, which is the remaining product of the food-mass in the intestines after the peptone and glucose have been taken up and carried to the liver, is taken up and passes through the lacteals into the thoracic duct, and is gradually conveyed to the blood, as will be further described in our chapter on the Circulation. In our chapter on the Circulation we will explain how the blood carries the nutriment derived from the digested food to all parts of the body, giving to each tissue, cell, organ and part the material by which it builds up and repairs itself, thus enabling the body to grow and develop.
The liver secretes the bile, which is carried to the small intestine, as we have stated. It also stores up a substance called glycogen, which is formed in the liver from the digested materials brought to it by the portal vein (as above explained). Glycogen is stored up in the liver, and is afterwards gradually transformed, in the intervals of digestion, into glucose or a substance similar to grape sugar. The pancreas secretes the pancreatic juices, which it pours into the small intestine, to aid in intestinal digestion, where it acts chiefly upon the fatty portions of the food. The kidneys are located in the loins, behind the intestines. They are two in number and are shaped like beans. They purify the blood by removing from it a poisonous substance called urea and other waste products. The fluid secreted by the kidneys is carried by two tubes, called ureters, to the bladder. The bladder is located in the pelvis and serves as a reservoir for the urine, which consists
