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.