ABSORPTION. 57 



as well as to be concerned in the absorption of those fluids which 

 require no elaboration. 



The fluid that is found in the lacteals is called chyle, and is almost 

 invariably the same in composition, no matter how great the diversity 

 of food from which it is obtained. From this fact the inference is 

 drawn, that the lacteals (or rather the absorbent cells amongst which 

 they originate) have the power of selcctmg the particles of which the 

 chyle is composed ; while they reject any other ingredients which 

 may be contained in the fluid of the intestines. 



The milky colour of the chyle is owing to tfie presence of minute 

 corpuscles called chyle globules. It also contains fat, albumen, fibrine, 

 and salts in varying quantities. 



The course of the chyle, afl:er leaving the intestinal canal, is 

 through the chyliferous vessels and ganglia of the mesentery, into the 

 receptaculum chyli or commencement of the thoracic duct, along 

 which it passes to enter the circulation at the point where the left 

 internal jugular and subclavian veins unite. During this passage it 

 undergoes several marked changes in its physical and vital properties. 

 When it first leaves the intestine its principal constituent is fax ; if 

 examined in the lacteal vessels of the mesentery, at a point between 

 the mesenteric ganglia and the receptaculum chyli, the fat will be 

 found to have diminished in quantity, while albumen will be in maxi- 

 mum quantity and jibrine in medium quantity ; and a slight coagula- 

 bility will also be manifested. The chyle taken from the thoracic 

 duct contains little or no fat, a medium quantity of albumen, and a 

 maximum quantity of fibrine, and is now distinctly coagulable, and 

 has a slight rosy tint. These circumstances have given rise to the 

 belief that the chyle, as it proceeds, becomes more and more anima- 

 lised, or transformed into the nature of the beifilg to be nourished. 

 MM. Tiedmann and Gmelin infer that it is to the action of the 

 mesenteric glands, that the chyle owes these important changes in its 

 nature ; — the fluid in its passage through them, obtaining from the 

 blood circulating in them, the new elements which animalise it. 



The chyle corpuscles are supposed by Dr. Carpenter to originate 

 in the mesenteric ganglia and to be the altered epithelium cells which 

 line the lacteals in their course through these bodies. Their function 

 is, according to this author, to convert the albumen into fibrine, since 

 they are found to be most abundant where this process is going on. 



Internal, or interstitial absor'ption, is efli3cted by agents strongly 

 resembling those concerned in the absorption of chyle. One part of 

 the apparatus, the thoracic duct, is common to both. The lymphatics 

 are distributed through the greater part of the body, especially upon 

 the skin. They have never been found to commence by closed or 

 open extremities ; but seem to form a network from which the trunks 

 arise. In their course they pass through glands, called lymphatic 

 glands, which exactly resemble in structure and function those of 

 the mesentery. The same agents, — cells, — are probably concerned 



