ABSORPTION. 159 



Cerebro-spinal fluid has the identical appearance of lymph, but 

 differs from it in chemical properties and composition. 



Synovial fluid of joints differs from true lymph in that it con- 

 tains mucin or mucinlike bodies and a high percentage of solids. 



Chyle is the term used to designate the fluid of the lacteal sys- 

 tem during active digestion, particularly of fats. It is an opaque, 

 whitish, milky fluid, neutral or slightly alkaline in reaction. The 

 color of the chyle is due to the presence in it of numerous fatly 

 granules, each surrounded by an albuminous envelope, very minute, 

 though uniform in size. Their fatty nature becomes evident when 

 they are treated with ether, for they are immediately dissolved. 

 Varying quantities of the fat give different shades of whiteness to 

 the chyle. Thus, in addition to the constituents of the lymph, the 

 chyle contains a large amount of fat, which is its characteristic fea- 

 ture. During fasting the chyle in the lacteals resembles ordinary 

 lymph. 



As the chyle passes on toward the thoracic duct, especially when 

 traversing some of the mesenteric glands, it is elaborated. As a 

 result there are fewer fat-particles, but there now begin to appear 

 corpuscles to which the name chyle-corpuscles is applied. Further, 

 it now gains the ability to coagulate spontaneously. As the chyle 

 advances in the thoracic duct the corpuscles become more numer- 

 ous, and the larger and firmer becomes the clot when the chyle is 

 withdrawn from its vessels. The clot is like that of blood when only 

 white corpuscles are present. Its ability to coagulate is due to the 

 disintegration of the lymph-corpuscles which supply it with the 

 necessary fibrin-factors. 



Flow of Lymph and Chyle. 



The lymph and chyle always run in a centripetal direction from 

 the periphery to the center under the influence of various forces. 

 The villi contract and push their contents in a centripetal course, 

 aided by the contractions of the intestinal muscles. The dilatation 

 of the blood-vessels at each contraction of the heart pushes the 

 lymph out of the perivascular spaces. 



Once the lymph and chyle are in the vessels they continue to 

 move by the muscular contraction of the walls of these vessels, and 

 this movement can only take place in a centripetal direction by rea- 



Iion of the arrangement of the valves. The lymphatic ganglia, by 

 heir structure, offer a resistance to the circulation of the lymph, 

 )ut their fibrous covering and unstriped muscles favor the flow. 



