=The Lymphatics.=—The lymphatics occur in all parts of the body, and in many respects resemble the veins, one of the most striking similarities being that the lymphatics contain valves just the same as the venous system. The lymphatic capillaries are arranged in the form of a net work and resemble closely in structure the blood capillaries. These capillaries then unite to form the lymph vessels and these then convey the lymph to the subclavian veins. The lymph is a colorless fluid and contains numerous blood corpuscles known as lymphocytes. But in those lymphatic vessels, which have their origin in the walls of the small intestines, the lymph, especially during digestion, contains a great amount of fat, so that it has a milky appearance, and for this reason the lymphatics of this region, have been termed lacteals. There are two main lymphatic trunks, the one on the left side is called the thoracic duct. This duct extends from the lower border of the second lumbar vertebra, through the entire length of the thorax, and opens into the left subclavian vein, close to the point where it is joined to the left internal jugular. It receives the lymph from the lower limbs, the pelvic walls and viscera, the abdominal walls and viscera; the lower part of the right half and the whole of the left half of the thoracic viscera, the left side of the neck and head and the left arm. [Illustration: FIG. 4—Lymphatics of the leg.] The other duct is called the right lymphatic duct and receives lymph from the upper part of the right side of the thoracic wall, part of the right side of the diaphragm and the right lobe of the liver, the whole of the right arm and neck and right side of the head. This trunk is very short and empties its supply of lymph into the right subclavian vein. Receptaculum chyli is the expanded portion of the thoracic duct just at its beginning. Its function is to receive the lacteals which come from the villi of the intestines. Lymph glands are the enlargements of the lymph vessels. They occur frequently in the lymphatic system, being most numerous in the axillary space, the cervical region (in the neck) and in Scarpa's triangle. The lymphatic system aids greatly in warding off such diseases as blood poisoning, anthrax, etc. _The lacteals_ are the lymphatics which carry the chyme from the villi of the intestines and deposit it in the receptaculum chyli. =Glands.=—The glands of the human body are divided into three classes called tubular, alveolar and tubulo-alveolar glands. _Tubular Glands._—In these, the secreting portion consists of a long or short tubule, which may be relatively straight or variously twisted, one end of which ends blindly, while the other end opens on the free surface or into a duct. Tubular glands may be simple, or having only a single tubule; they may be simple branched, having more than one tubule; or they may be compound branched, thus resembling the branching of a tree.