ABSORPTION. 



167 



Fig. 41. 



that, on arriving at the entrance of the general circulation, both 

 these newly absorbed ingredients have become already assimilated 

 to those which previously existed in the blood. 



The chyle in the intestine consists, as we have already mentioned, 

 of oily matters which have not been chemically altered, but simply 

 reduced to a state of emulsion. In chyle drawn from the lacteals 

 or the thoracic duct (Fig. -Al), it still presents itself in the same 

 condition and retains all the 

 chemical properties of oil. 

 Examined by the microscope, 

 it is seen to exist under the 

 form of fine granules and 

 molecules, which present the 

 ordinary appearances of oil 

 in a state of minute subdivi- 

 sion. The chyle, therefore, 

 does not represent the entire 

 product of the digestive pro- 

 cess, but contains only the 

 fatty substances, suspended 

 by emulsion in a serous fluid. 



During the time that intes- 

 tinal absorption is going on, 



n , . Drcr, from the D^n The molecules vary iu size 



alter a meal containing fatty from i-io.oootu of au iuch downward, 

 ingredients, the lacteals may 



be seen as white, opaque vessels, distended with milky chyle, pass- 

 ing through the mesentery, and converging from its intestinal bor- 

 der toward the receptaculum chyli, near the spinal column. During 

 their course, they pass through several successive rows of mesenteric 

 glands, which also become turgid with chyle, while the process of 

 digestion is going on. The lacteals then conduct the chyle to the 

 receptaculum chyli, whence it passes upward through the thoracic 

 duct, and is finally discharged, at the termination of this canal, into 

 the left subclavian vein. (Fig. 42.) It is then mingled with the 

 returning current of venous blood, and passes into the right cavities 

 of the heart. 



The lacteals, however, are not a special system of vessels by them- 

 selves, but are simply a part of the great system of " absorbent" or 

 " lymphatic" vessels, which are to be found everywhere in the integu- 

 ments of the head, the parietes of the trunk, the upper and lower 

 extremities, and in the muscular tissues and mucous membranes 



CHYLE FROM COMXKKCEMKXT < >' T H <> R A c i o. 



