684. If the mucous coat of the small intestines be examined some hours after a meal, the lacteals are seen turgid with chyle, covering its entire surface (fig. CLXXV. 1). These vessels, which are sometimes of such magnitude and in such numbers as entirely to conceal the ramifications of the blood-vessels, unite freely with each other, and form a net-work, from the meshes of which proceed branches which, successively uniting, form branches of a larger size (fig. CLXXV. 2). These larger branches perforate the mucous coat and pass for some way between the mucous and the muscular tunics: at length they perforate both the muscular and the peritoneal coats, when, from having been on the inside of the intestine, they get on the outside of it (fig. CLXXVI. 3, 4), and are included, like the intestine itself, between the layers of the mesentery. All the different sets of lacteals converging and uniting together, form an exceedingly complicated plexus of vessels within the fold of the mesentery. Radiating from this plexus, the lacteals advance forwards until they reach the glands, called, from their being placed between the fold of the mesentery, the mesenteric (figs. CLXXVI. 5 and 6, and clxxvii. 2 and 3); rounded, oval, pale-coloured bodies, consisting of two sets, arranged in a double row (figs. CLXXVI. 5 and 6, and CLXXVII. 2 and 3); the set nearest the intestine (fig. CLXXVII. 2) being considerably smaller than the succeeding set (fig. CLXXVII. 3). [Illustration: Fig. CLXXVII. View of the course of the Thoracic Duct from its origin to its termination. 1. Lacteal vessels emerging from the mucous surface of the intestines. 2. First order of mesenteric glands. 3. Second order of mesenteric glands. 4. The great trunks of the lacteals emerging from the mesenteric glands, and pouring their contents into—5. The receptacle of the chyle. 6. The great trunks of the lymphatic or general absorbent system terminating in the receptacle of the chyle. 7. The thoracic duct. 8. Termination of the thoracic duct at—9. The angle formed by the union of the internal jugular vein with the subclavian vein.] 685. On reaching the first series of glands (fig. clxxvii. 2), the lacteals penetrate the substance of the gland, in the interior of which they communicate with each other so freely, and form such innumerable windings, that the gland seems to consist of a congeries of convoluted lacteals. Emerging from the first series of glands, the lacteals proceed on their course to the second series (fig., CLXXVII. 3), which they penetrate, and in the interior of which they present the same convoluted appearance as in the first set. On passing out of this second series of glands, the lacteals unite together, and compose successively larger and larger branches, until at length they form two or three trunks (fig. CLXXVII. 4), which terminate in the small oval sac (fig. CLXXVII. 5), termed the receptacle of the chyle (receptaculum chyli).