ABSORBENTS OF THE ABDOMINAL VISCERA. 491 



The internal iliac lymphatic glands, a numerous series placed on the 

 internal iliac artery, and the sacral glands, placed in the hollow of the 

 sacrum, receive the lymphatics from the pelvic viscera and parietes. 



The lumbar lymphatic glands are very large and numerous ; they are 

 placed in front of the lumbar vertebrae, around the aorta and vena cava. 

 To these proceed the efferent vessels of the glands already mentioned, as 

 well as those which accompany several of the branches of the abdominal 

 aorta. 



The efferent absorbent vessels which proceed from the lumbar glands pro- 

 gressively increase in size, while their number diminishes, and at length 

 they unite into a few trunks, which, with those of the lacteals, form the 

 origin of the thoracic duct. 



The deep lymphatics of the abdominal wall in part pass along the 

 circumflex iliac and epigastric arteries to the external iliac glands ; the 

 greater number are directed backwards with the ilio-lumbar and lumbar 

 arteries, and, being joined by the lymphatics from the muscles of the back, 

 pass behind the psoas muscle to the vertebral column, where they enter the 

 lumbar glands. 



The lacteals (vasa lactea, chylifera) commence in the coats of the intes- 

 tines, by a very close plexus, and extend to the thoracic duct, in which 

 they all terminate : they are derived in far larger numbers from the small 

 than from the large intestine, so that they abound in the mesentery, and 

 particularly in that of the jejunum and ileum. Two series of absorbent 

 vessels are found along the tube of the intestine, having different positions 

 and directions : those nearest to the outer surface of the intestine run 

 longitudinally in the course of the canal, lying beneath the peritoneal coat ; 

 whilst others, placed more deeply between the muscular and mucous coats, 

 run transversely round the intestine, and are directed thence with the 

 arteries and veins along the mesentery, enclosed between the two layers of 

 the peritoneum. (Cruikshank, Anatomy of the Absorbent Vessels, p. 162.) 

 Sometimes the more superficial absorbents of the intestine are named 

 lymphatics, to distinguish them from the deep set which are those which 

 absorb the chyle from the cavity of the intestine. According to Teichmann 

 (Das Saugader- system, 1861, p. 75), the two plexuses have no capillary 

 anastomoses, but communicate only through valved vessels : this they do 

 freely. The lacteals, having entered the mesentery, take the course of the 

 blood-vessels, and pass through numerous lymphatic glands (mesenteric 

 glands). 



The mesenteric glands vary in number from a hundred and thirty to a 

 hundred and fifty ; and in the healthy state are seldom larger than an 

 almond. They are most numerous in that part of the mesentery which 

 corresponds with the jejunum ; and they seldom occur nearer to the 

 attached border of the intestine than two inches. In mesenteric disease 

 they are subject to enlargement, and become the seat of unhealthy deposits. 

 Small glands in limited numbers are also disseminated irregularly between 

 the folds of the peritoneum connected with the large intestines. 



Having passed through these glands, the lacteals gradually unite as they 

 approach the attached border of the mesentery, and so become diminished 

 in number but increased in size, until at length, near the root of the supe- 

 rior mesenteric artery, only two or three trunks remain, which end in the 

 thoracic duct. Sometimes, however, six or seven of these vessels open 

 separately into the commencement of the duct. Those from the descending 

 colon and its sigmoid flexure usually join some of the lumbar lymphatics, or 



