last chapter—the point at which the nourishment of the food, taken up by the blood which assimilates it, reaches the heart, which sends it out on its errand of nourishing the body.
The blood starts on its journey through the arteries, which are a series of elastic canals, having divisions and subdivisions, beginning with the main canals which feed the smaller ones, which in turn feed still smaller ones until the capillaries are reached. The capillaries are very small blood-vessels measuring about one three-thousandth of an inch in diameter. They resemble very fine hairs, which resemblance gives them their name. The capillaries penetrate the tissues in meshes of network, bringing the blood in close contact with all the parts. Their walls are very thin and the nutritious ingredients of the blood exude through their walls and are taken up by the tissues. The capillaries not only exude the nourishment from the blood, but they also take up the blood on its return journey (as we will see presently) and generally fetch and carry for the system, including the absorption of the nourishment of the food from the intestinal villi, as described in our last chapter.
Well, to get back to the arteries. They carry the rich, red, pure blood from the heart, laden with health-giving nutrition and life, distributing it through large canals into smaller, from smaller into still smaller, until finally the tiny hair-like capillaries are reached and the tissues take up the nourishment and use it for building purposes, the wonderful little cells of the body doing this work most intelligently. (We shall have something to say regarding the work
