CHAPTER XI. 

 ABSORPTION. 



113. WE have now to take into consideration the means by 

 which the substance of the blood is replenished. This is 

 effected by absorption, or the sucking up of material into 

 vessels, partly from the alimentary canal, and partly from the 

 tissues. Matter from both these sources is absorbed by the 

 capillary blood-vessels, and so carried into the veins; but 

 there is another set of vessels, the lymphatics, more especially 

 referred to when absorbents are spoken of, whose whole office 

 is one of absorption. 



The lymphatics or absorbents are a system of vessels 

 with delicate walls, and having the appearance of long and 

 slender threads when they are empty. The trunk into which 

 the majority of them pour their contents, the thoracic duct, 

 is no greater in diameter than a small crow quill, and some- 

 times not so large. The thoracic duct begins in the upper 

 part of the back of the abdomen, where it forms a dilatation 

 four or five times its width in the rest of its course, named 

 the receptaculum chyli, and runs up through the thorax in 

 front of the vertebral column, to open, at the root of the neck, 

 into the angle of junction of the left jugular and left sub- 

 clavian veins. It receives the absorbents from the whole 

 body, with the exception of the right half of the thorax, 

 right arm, and right side of the head and neck. The 

 absorbents from these parts unite to form a short trunk, 

 which opens into the angle of junction of the right jugular 

 and subclavian veins, and is called the right lymphatic duct. 



The lymphatic vessels are difficult to study on account of 

 their slenderness, and because they are thickly beset with 

 valves like those of veins, which, in most instances, effectually 



