504 



LYMPHATIC GLANDS. 



[sect. 218. 



followed by some striped lamellae, and then by an elastic reticulate 

 coat, with its fibres disposed longitudinally ; still the whole tunica 

 intima scarcely measures o - oo6'" to o*oi'" in thickness. The tunica 

 media, 0*025 " thick, commences by a very thin layer of longi- 

 tudinal connective tissue, with fine elastic fibres, while the re- 

 mainder is made up of a transverse muscular laminae, with fine 

 elastic fibres. The tunica adventitia, lastly, contains longitudinal 

 connective tissue, together with elastic fibres, and separate reticu- 

 lated fasciculi of longitudinal muscular fibres. — The valves of this 

 canal, and of the lymphatics in general, completely agree with 

 those of the veins. — The blood-vessels which supply the coats of 

 the lymphatics, present the same condition on the thoracic duct 

 as on the veins.— No nerves have hitherto been found on them. 



Briicke has recently attempted to prove, on physiological grounds, that 

 the lymphatics at their origin cannot be provided with any walls (Denkschr. 

 d. Wien. Akad. vi. pp. 22, et seq.). Setting aside the boldness of such a method 

 of proof, in the imperfect state of this branch of physiology, Briicke's deduc- 

 tions are opposed to actual facts. There is no difficulty in convincing one- 

 self that certain lymphatics in the tadpole do really begin by positively 

 closed extremities. 



§ 218. Lymphatic Glands. — The larger lymphatic glands, in 

 Fig. 207. their normal condition, consist, like the 



suprarenal capsules, of an envelope, of a cor- 

 tical, and of a medullary substance. The 

 envelope encloses the gland completely, with 

 the exception of one or more places where 

 the larger blood-vessels enter, and the 

 efferent lymphatic vessels pass out ; this 

 may be designated the ' hilus ' of the gland. 

 The envelope is more delicate on the glands 

 situated in the large cavities of the body, 

 than on those of the external regions : in 

 its structure it is wholly composed, in man 

 at least, of connective tissue, in which are 

 interspersed numerous fine elastic fibrils 

 (nuclear fibres), and their formative ele- 

 ments, the plasmatic cells. In the lower 

 animals, according to 0. Hey f elder, especially 

 in the mouse, contractile fibre-cells also 

 occur in it ; but Beck and Remak have not 

 been able to find them (Jahresb., v. Henle, 

 1855, p. 37). — The cortical substance, which is perceptible on the 



A lymphatic gland, of the 

 inguinal region of man, 

 double the actual size. «. 

 vasa inferentia; b. vas ef- 

 ferens coming out of the 

 hilus ; c. alveoli of the sur- 

 face of the cortex, seen 

 through the envelope. 



