286 ABSORPTION. 



by the lymph, which is continually brought to the gland and 

 conveyed away from it by lymphatic vessels ; those which 

 bring it being termed afferent vessels, and those which take it 

 away efferent vessels. The former enter the cortical part of 

 the gland and open into its alveoli, at the same time that they 

 lay aside all their coats except the epithelial lining, which 

 may be said to continue to line the lymph-path into which the 

 contents of the afferent vessels now pass. The efferent vessels 

 begin in the medullary part of the gland, and are continuous 

 with the lymph-path here as the afferent vessels were with the 

 cortical portion ; the epithelium of one is continuous with that 

 of the other. 



Bloodvessels are freely distributed to the trabecular tissue 

 and to the gland-pulp (Fig. 98). 



Properties of Lymph and Chyle. 



The fluid, or lymph, contained in the lymphatic vessels is, 

 under ordinary circumstances, clear, transparent, and color- 

 less, or of a pale yellow tint. It is devoid of smell, is slightly 

 alkaline, and has a saline taste. As seen with the micro- 

 scope in the small transparent vessels of the tail of the tad- 

 pole, the lymph usually contains no corpuscles or particles of 

 any kind ; and it is probably only in the larger trunks in 

 which, by a process similar to that to be described in the 

 chyle, the lymph is more elaborated, that any corpuscles are 

 formed. These corpuscles are similar to those in the chyle, 

 but less numerous. The fluid in which the corpuscles float 

 is commonly and in health albuminous, and contains no fatty 

 particles or molecular base ; but it is liable to variations ac- 

 cording to the general state of the blood, and that of the organ 

 from which the lymph is derived. As it advances towards the 

 thoracic duct, and passes through the lymphatic glands, it be- 

 comes, like chyle, spontaneously coagulable from the formation 

 of fibrin, and the number of corpuscles is much increased. 



The fluid contained in the lacteals, or lymphatic vessels of 

 the intestine, is clear and transparent during fasting, and 

 differs in no respect from ordinary lymph ; but during diges- 

 tion, it becomes milky, and is termed chyle. 



Chyle is an opaque, whitish fluid, resembling milk in ap- 

 pearance, and having a neutral or slightly alkaline reaction. 

 Its whiteness and opacity are due to the presence of innumer- 

 able particles of oily or fatty matter, of exceedingly minute 

 though nearly uniform size, measuring on the average about 

 00077 of an inch (Gulliver). These constitute what Mr. Gul- 



