236 OF THE BILK. 



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arise from, blood-vessels,* which are both very numc- 

 , rous and in some instances very large, but of different 

 descriptions, as we shall state particularly. 



371. The first blood-vessel to be noticed is the vena 

 portarum, whose dissimilarity from other veins, both 

 in its nature and course, was formerly hinted at. (97) 

 Its trunk is formed from the combination of most of 

 the visceral veins belonging to the abdomen, is sup- 

 ported by a cellular sheath called the capsule of 

 Glisson,f and, on entering the liver, is divided into 

 branches which are subdivided more and more as they 

 penetrate into the substance of the organ, till they 

 become extremely minute and spread over every part. 

 Hence Galen compared this system to a tree whose 

 roots were dispersed in the abdomen and its. branches 

 fixed in the liver. % 



372. The other kind of blood-vessels belonging to 

 the liver, are branches of the hepatic artery,' which 

 arises from the cceliac, is much inferior to the vena 

 portae in size and the number of its divisions, but 

 spreads by very minute ramifications throughout the 

 substance of the organ. 



373. The extreme divisions of these two vessels ter- 

 minate in true veins, which unite into large venous 

 trunks running to the vena cava inferior. 



374. These extreme divisions are . inconceivably mi- 

 nute and collected into very small glomerules,§ which 



* Haller, Iconet Anat. Fascia ii. tab. iii. 



f Glisson, Anatomia Hepatis. p. .'{05 sq. 1659. . 



X Dt Vrnamm Arttriammque dmtctione. p. 109. Opera: Basil. 1562. el. i. 



S Nest. Maximeow. Anibodick, Dt Htpatc. Argent. 1775. 4to: 



