3S THE LTMPH AND CHYLE. 



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. Both lacteals and lymphatics, in pro- 

 ceeding to their destination, pass into and out of certain small, solid, 

 and vascular bodies, named lymphatic 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. 



Thus much having been explained to render intelligible wliat follows, 

 we may now consider the lymph and the chyle, which, as will be seen, 

 are intimately related to the blood. 



The lymph may be procured free from admixture of chyle, and in 

 quantity sufficient for examination, from the larger lymphatic vessels 

 of the horse or ass. It may also be obtained by opening the thoracic 

 duct of an animal that has fasted for some time before being killed. 

 It is a thin fluid, transparent and colourless, or occasionally of a pale 

 yellow hue ; its taste is saline, its smell faint and scarcely perceptible, 

 and its reaction alkaline. Sometimes the lymph has a decided red tint, 

 of greater or less depth, which becomes brighter on exposure to the air. 

 This redness is due to the presence of coloured corpuscles, like thoseof 

 the blood : and it has been sometimes supposed, that such corpuscles 

 exist naturally in the lymph, in greater or less quantity ; but they are 

 more probably introduced into the lymphatic vessels accidentally. It 

 can, in fact, be shown, that when an incision is made into a part, the 

 blood very readily enters the lymphatics which are laid open, and passes 

 along into larger trunks ; and in this way blood is conveyed into the 

 thoracic duct, or any other large vessel, exposed as usual by incision 

 immediately after the animal is killed. Indeed, mere rough handling 

 of some organs, such as the liver and spleen, will rupture the fine vessels 

 and cause the contents of the issuing lymphatics speedily to become red 

 from admixture of blood. 



The lymph, when examined with the microscope, is seen to consist of 

 a clear liquid, with corpuscles floating in it. These " lymph-corpus- 

 cles," or lymph-globules, agree entirely in their characters with the 

 pale corpuscles of the blood, which have been already described 

 (page 23). It is alleged that some of the lymph corpuscles have a 

 yellowish tint. Occasionally, smaller particles are found in the lymph ; 

 also, but more rarely, a few oil globules of various sizes, as well as red 

 blood-corpuscles, the presence of which lias just been referred to. 



The liquid part (lymph-plasma) bears a strong resemblance in its 

 physical and chemical constitution to the plasma of the blood ; and 

 accordingly, lymph fresh-drawn from the vessels coagulates after a few 

 minutes' exposure, and separates after a time into clot and serum. This 

 change is owing to the combination of the constituents of the fibrin 

 contained in the lymph-plasma, and in this process most of the cor- 

 puscles are entangled in the coagulum. The serum, like the corre- 

 sponding part of the blood, consists of water, albumin, extractive 

 matters, fatty matters in very sparing quantity and salts. Sugar 

 exists in small quantity in the lymph, and urea, in the pi'oportion of 

 from O'Ol to 0-02 per cent. ; leucin has also been found, at least in the 

 lymphatic glands. 



