120 LYMPHATIC GLANDS. 



system the nutrient material for constructing the body, 

 the former conveys out the same material, after it has per- 

 formed its part in the ceconomy, and becomes useless; or 

 rather carries it into the venous blood, to become repurified 

 in the lungs, again to enter the system. 



This system is divided into the lymphatic glands and 

 the absorbent vessels. 



The lymphatic or absorbent glands, called also conglo- 

 bate, are very numerous both in the trunk and extremities, 

 and are generally seen in clusters or chains, as in the mesen- 

 tery and neck. Their color is reddish, inclining to a grayish 

 hue, though the bronchial are black and those of the lesser 

 omentum sometimes yellow. Their consistence is firm and 

 resisting. They are surrounded by a firm capsule of cel- 

 lular membrane, which sends processes within their sub- 

 stance to unite the different parts, as blood vessels and 

 nerves, with which they are liberally supplied. Their size 

 varies from that of a currant to that of an almond. Their 

 form is round or oval, though some are irregular and 

 lobulated. They are movable in the healthy state, but 

 become firmly fixed by inflammation. Their structure is not 

 fully determined, though they seem to consist essentially 

 of an interlacement of lymphatic vessels, which enter these 

 glands, and after forming a kind of plexus, leave them. 



Those entering are called vasa infereritia; those leaving, 

 vasa efferentia. 



Cells are spoken of as lying between these two kinds of 

 vessels, into which they open, and containing a peculiar 

 fluid. The absorbent vessels are divided into the lymph- 

 atics and lacteals, so called from the color of the fluid they 

 respectively carry, which is transparent in the former and 

 milky in the latter. 



Some of these vessels were seen in the mesentery of a 

 goat by Herophilus and Erasistratus, 280 years before the 

 Christian era. Aselius, an Italian anatomist, in 1622 re- 

 discovered or confirmed the original observations of absorb- 

 ents in the mesentery, made so long before by Herophilus 

 and Erasistratus, and found that these vessels took up the 



