532 



THE TISSUES. 



small, pit-like, elongated or rounded aperture, T J 5 to T J 7 of an inch 



in diameter, in the mucous membrane. (Fig. 362.) The function 

 of these closed follicles is also unknown. 



The bloodvessels of the preceding glands have the same rela- 

 tions as in the small intestine. (Fig. 353.) Nothing is known of 

 either the lymphatics or the nerves of the mucous membrane of 

 the large intestine. 



THE APPENDAGES TO THE ALIMENTAEY CANAL. 



1. The Liver. 



Keferring to the works on descriptive anatomy for all other par- 

 ticulars in regard to the liver, such only will be specified here as 

 are necessary to give an idea of its minute structure. 



The vena portae, the hepatic artery, and the hepatic duct enter 

 the transverse fissure of the liver, and, subdividing, at last termi- 

 nate the first two in a capillary plexus from which the hepatic 

 vein commences, and the last in immediate contact with the plexus. 

 In the pig, and some other animals, the minute structures just men- 

 tioned are so inclosed as to constitute distinct lobules, and it is the 

 lobules in this animal which Kiernan first accurately described 

 and figured. In man, however, nothing of the kind occurs, as 

 E. H. Weber first demonstrated; the various structural elements 

 being intimately connected throughout the whole organ. Still, the 



distribution of the capillaries 

 and ducts is such as to give 

 rise to little islets in the liver, 

 somewhat analogous to the lo- 

 bules above mentioned. These 

 are masses of the hepatic sub- 

 stance, ^ to 1*2 of an inch in 

 diameter, containing some of the 

 minutest branches of the vena 

 portse and the hepatic artery ex- 

 ternally, and giving off in their 

 centre a small twig of the hepa- 

 tic vein. Between these vessels 



Horizontal section of three superficial lobules of the portal hepatic pleXUS of Ca- 



the liver, showing the two principal systems of r) ni r | p a } s f oun( ] (Y\cr 863 "l 

 bloodvessels. 1, 1. Interlobular veins proceeding 



from the hepatic veins. 2, 2. Interlobular (portal- The hepatic ducts arise in the 

 hepatic) plexus, formed by branches of the portal , , . in 



vein (Pig.) meshes between the vessels of 



Fig. 363. 



