THE LYMPH AND CHYLE. xlvii 



coagulate being no longer opposed, is allowed to prevail. At the same time it is not 

 inconsistent with this theory to admit the positive efficacy of contact with foreign or 

 dead matter in promoting coagulation. Mr. Lister,* on the other hand, considers 

 that the blood has no spontaneous tendency to coagulate, either within or without 

 the vessels, but that the coagulation is brought about in drawn blood by contact with 

 foreign matter. Accepting the conclusion of Schmidt, that globulin and fibrinogen 

 are necessary to the evolution of fibrin, he thinks that, if these bodies unite in 

 ordinary chemical combination, the action of foreign matter may determine their 

 union, as spongy platinum promotes the combination of oxygen and hydrogen. He 

 considers that the living vessels do not exert any action to prevent coagulation, but 

 that their peculiarity, as distinguished from an ordinary solid, consists in the remark- 

 able circumstance that their lining membrane, in a state of health, is wholly negative 

 in its relation to coagulation, and does not cause that molecular disturbance, so to 

 speak, which is produced in the blood by all ordinary matter. When the vessels lose 

 their peculiar property by death, or become seriously altered by disease or injury, 

 their contact with the blood induces coagulation like that of an extraneous body. 

 Finally, it may be observed, that in any attempted explanation of the coagulation of 

 the blood, it is well to bear in mind that there is a purely physical or chemical 

 phenomenon, which, as suggested by Mr. Graham, has a certain analogy to it, namely, 

 the change from the liquid to the insoluble state so easily induced in colloidal matter 

 by slight external causes. 



THE LYMPH AUD CHYLE. 



A transparent and nearly colourless fluid, named " lymph," is conveyed 

 into the blood by a set of vessels distinct from those of the sanguiferous 

 system. These vessels, which are named " lymphatics," from the nature of 

 their contents, and " absorbents," on account of their reputed office, take 

 their rise in nearly all parts of the body, and, after a longer or shorter 

 course, discharge themselves into the great veins of the neck ; the greater 

 number of them previously joining into a main trunk, named the thoracic 

 duct, a long narrow vessel which rises up in front of the vertebrae, and 

 opens into the veins on the left side of the neck, at the angle of union of 

 the subclavian and internal jugular ; whilst the remaining lymphatics termi- 

 nate in the corresponding veins of the right side. The absorbents of the 

 small intestine carry an opaque white liquid, named " chyle," which they 

 absorb from the food as it passes along the alimentary canal ; and, on 

 account of the milky aspect of their contents, they have been called the 

 "lacteal vessels." But in thus distinguishing these vessels by name, it 

 must be remembered, that they differ from the rest of the absorbents only 

 in the nature of the matters which they convey ; and that this difference 

 holds good only while digestion is going on ; for at other times the lacteals 

 contain a clear fluid, not to be distinguished from lymph. The lacteals 

 enter the commencement of the thoracic duct, and the chyle, mingling with 

 the lymph derived from the lower part of the body, is conveyed along that 

 canal into the blood. 



Glands. Both lacteals and lymphatics, in proceeding to their destination, 

 pass into and out of certain small, solid, and vascular bodies, named lym- 

 phatic glands, which have a special structure and internal arrangement, as 

 will be afterwards described ; so that both the chyle and lymph are sent 

 through these glands before being mixed with the blood. 



This much having been explained to render intelligible what follows, we 



* On the Coagulation of the Blood ; the Croonian Lecture for 1863, Proceedings of the 

 Royal Society, vol. xii. p. 580. 



