THE VITAL PRINCIPLE — THE BLOOD. 23 



duary matter are gradually carried forwards ; 

 the progress of the former is peculiarly slow, 

 for it adheres from its tenacity to the villi (or 

 velvet-like pile) of the inner coat of the intes- 

 tine, and is, moreover, obstructed by certain 

 valvular folds, termed valvules conniventes. All 

 this is by design, as it affords time for a system 

 of vessels, termed lacteals, to absorb it. These 

 lacteals, so called from the milky nature of the 

 fluid they contain, commence by innumerable 

 open mouths on the surface of the villi ; they 

 then pass through the coats of the intestine, and 

 run through the layers of the mesentery, enter 

 into the first series of mesenteric glands, in which 

 they become extremely convoluted, and com- 

 municate freely with each other. After emerg- 

 ing from these glands, the chyliferous vessels 

 continue their course between the layers of the 

 mesentery, and enter a second series of glands, 

 in which they again become convoluted. On 

 freeing themselves from the second set of glands, 

 they converge into a receptacle for the chyle, 

 which constitutes the commencement of the 

 thoracic duct. Here we must observe, that in 

 this receptacle also terminate another set of 

 vessels, termed absorbents, and also lymphatics, 

 (from the colourless and pellucid fluid, or lymph, 

 which they contain.) These absorbents arise 

 from every portion of the frame, and are ever 

 active in removing the materials of which it is 

 composed, the minute arteries depositing fresh 

 materials in their place, so that the body is in 

 a perpetual process of change, by agencies 



