=52.= This, then, is what becomes of the food-stuffs:-- The fats are broken up by the bile and pancreatic juice into minute particles. These minute particles, we do not exactly know how, pass through the epithelium of the villus into the lacteal vessels, from the lacteals into the thoracic duct, and from the thoracic duct into the vena cava. Thus the fats we eat get into the blood. The starch is changed into sugar in the mouth by saliva, and in the intestine by the pancreatic juice; but sugar passes readily through membranes, and so slips into the blood capillaries of the walls of the alimentary canal. Thus all the sugar we eat, and all the goodness of the starch we eat, pass into the blood. The proteids are dissolved in the stomach by the gastric juice, and what passes the stomach is dissolved in the intestine, dissolved in such a way that it can pass through membranes; and thus proteids pass into the blood. Probably some of the sugar and proteids pass into the lacteals as well. The minerals are dissolved either in the mouth, or in the stomach, or in the intestine, and pass into the blood. And water passes into the blood everywhere along the whole length of the canal. When we eat a piece of bread, while we are chewing it in our mouth it is getting moistened and mixed with saliva. Part of its starch is thereby changed into sugar, and all of it is softened and loosened. Passing into the stomach, some of the proteids are dissolved out by the gastric juice, and pass into the blood, and all the rest of the bread breaks up into a pulpy mass. Passing then into the intestine, what is left of the starch is changed by the pancreatic juice into sugar, and is at once drained off either into the lacteals or straight into the blood. In the intestine what remains of the proteids is dissolved, till nothing is left but the shells of the tiny chambers in which the starch and proteids were stored up by the wheat-plant as it grew.