The larger of the lymph tubes is called the _thoracic duct_. This receives lymph from all parts of the body not drained by the right lymphatic duct, and empties it into the left subclavian vein. Connection is made with the subclavian vein on the upper side at the place where it is joined by the left jugular vein. The thoracic duct has a length of from sixteen to eighteen inches, and is about as large around as a goose quill. The lower end terminates in an enlargement in the abdominal cavity, called the _receptacle of the chyle_. It is provided with valves throughout its course, in addition to one of considerable size which guards the opening into the blood vessel. The lymphatics which join the thoracic duct from the small intestine are called the _lacteals_ (Fig. 28). These do not differ in structure from the lymphatics in other parts of the body, but they perform a special work in absorbing the digested fat (Chapter XI). *Lymphatic Glands.*—The lymphatic glands, sometimes called lymph nodes, are small and somewhat rounded bodies situated along the course of the lymphatic tubes. They vary in size, some of them being an inch or more in length. The lymph vessels generally open into them on one side and leave them on the other (Figs. 28 and 30). They are not glands in function, but are so called because of their having the general form of glands. They provide favorable conditions for the development of white corpuscles (page 29). They also separate harmful germs and poisonous wastes from the lymph, thereby preventing their entrance into the blood. *Relations of the Lymph, the Blood, and the Cells.*—While the blood is necessary as a carrying, or transporting, agent in the body, the lymph is necessary for transferring materials from the blood to the cells and _vice versa_. Serving as a physiological "go between," or medium of exchange, the lymph enables the blood to minister to the needs of the cells. But the lymph and the blood, everything considered, can hardly be looked upon as two separate and distinct liquids. Not only do they supplement each other in their work and possess striking similarities, but each is made in its movements to pass into the vessels occupied by the other, so that they are constantly mixing and mingling. For these and other reasons, they are more properly regarded as two divisions of a single liquid—one which, by adapting itself to different purposes,(27) supplies all the conditions of a nutrient fluid for the cells. *Movements of the Lymph.*—As compared with the blood, the lymph must be classed as a quiet liquid. But, as already suggested, it has certain movements which are necessary to the purposes which it serves. A careful study shows it to have three well-defined movements as follows: 1. A movement from the capillaries toward the cells. 2. A movement from the cells toward the capillaries.