LIVER OF MAMMALIA. 



491 



tunics, c, d, e, of the gut, in Man, to the extent shown in fig. 376, 

 before uniting to form the common receptacle within the terminal 

 prominence. 



The ' carrying arrangements ' of the bile are, thus, on a more 

 concentrated plan in the present than in 

 lower classes of Vertebrates. The human 

 cystic duct shows a series of crescentic folds 

 of the lining membrane, directed obliquely 

 round the canal, and so arranged as to give 

 the appearance of a spiral valve. Nume- 

 rous minute follicles, either branched or 

 clustered, open upon the mucous tract ot 

 the bile-ducts : in the smaller branches their 

 orifices are in two opposite longitudinal 

 rows. 



From the arrangement and localisation in 

 the ' lobule ' of the capillaries of the two 

 systems of veins, determined, together with 

 most that is of importance in hepatic struc- 

 ture, by the admirable research, skill, and 

 patience of Kiernan, an explanation has 

 been afforded of appearances otherwise un- 

 intelligible or misleading. 1 When the capil- 

 laries of the hepatic vein are gorged, as is 

 usual in an early stage of congestion, the 

 flattened surfaces of the lobules on the superficies of the liver 

 present the appearance in fig. 377. When the portal capillaries 

 377 378 



Hepato 



e d o 



ncreatic ampulla 

 human : magn. 



Lobules of liver with congested hepatic veins. 



Lobules of liver with congested porta veins. 



are congested, the peripheral parts of the lobules present the 

 deeper colour, as in fig. 378. So, in examining portions of the 



1 As e.g. the supposed distinction of ' cortical' and 'medullary' substances of some 

 authors ; of ' red ' and ' yellow ' substances of others. See clvii". p. 763. 



