120 ANATOMY OF THE RABBIT 



The conducting portion of the system comprises an extensive 

 series of canals, beginning as lymphatic capillaries in peripheral 

 organs, and ending as lymphatic trunks which empty into the great 

 veins. The lymphatic capillaries are terminal vessels, differing 

 from blood capillaries both in the character of their walls and in 

 their relations to other portions of the system, since they are not 

 interposed, as in the blood-vascular system, between vessels of a 

 larger order. The lymphatic capillaries begin blindly in the tissue 

 spaces, where they collect through their walls fluid derived from 

 the blood plasma by exudation through the walls of the blood 

 capillaries. The lymphatic capillaries unite to form larger vessels 

 and these are connected as extensive plexuses, at important points 

 in which the lymph nodes are distributed. The latter act as 

 strainers for the lymph, removing bacteria or other foreign particles 

 so that they will not be conveyed into the blood stream. They 

 also add to it new white blood cells. From them the vessels convey 

 the lymph to the lymphatic trunks. 



The lymphatic trunks of the anterior portion of the body (Fig. 

 C)7) are designated from their association with the corresponding 

 veins as jugular and subclavian. They enter the venous system on 

 either side at the point of junction of the internal and external 

 jugular veins or of the common jugular and subclavian (Fig. 111). 

 The lymphatic vessels of the posterior portion of the body, in- 

 cluding the intestine, usually largely unite in a lymph-reservoir at 

 about the level of the first lumbar vertebra, and from this the 

 lymph flows forward through a common canal, the thoracic duct. 

 The latter lies for the most part between the aorta and the vertebral 

 column, and traverses the thorax in this position to enter the 

 venous system at the same point as the jugular and subclavian 

 trunks of the left side. There are also retrosternal lymph-tracts 

 accompanying the internal mammary blood-vessels and functional 

 tests have shown that drainage from the abdominal cavity is 

 largely through these. They enter the jugular veins of their 

 respective sides just after the union of external and internal 

 jugulars. All these trunks are so thin-walled that it is not usually 

 possible to see them in ordinary dissection. 



The lymph or fluid present in lymph vessels and in the spaces 

 of lymph nodes and the tissue fluid in the tissues of the body are 



