THE LIVER. 539 



by which it loses some of its water, and probably undergoes other 

 changes." 



Thus the secreting cells at the surface of the islets probably take 

 the most active part in the secretion of bile, being first reached by 

 the portal blood, and while it also circulates more slowly. These 

 cells also first show an increase of oil-drops in cases of fatty de- 

 generation. The bile is formed by each individual cell, and trans- 

 ferred, by the tube inclosing the row of cells, to the ducts between 

 the islets. The very close contact in which the cells sometimes lie, 

 is accounted for by the great changes in bulk they are known so 

 readily to undergo. Hence the liver is a true gland, like the other 

 racemose glands; and not essentially distinct from them in struc- 

 ture, as has generally been asserted. 



The capillary network of the islets completely fills the interspaces 

 of the tubular network, before described (Fig. 118). The capilla- 

 ries average about 3^3 to 22 V^ f an i nc h i* 1 diameter; being 

 somewhat less than the rows of the cells in the tube-network. The 

 meshes between the vessels of course correspond in diameter with 

 that of the columns of the cells, being 3 ^V(T to g J of an inch. A 

 transverse section of the islets (in the pig), is shown by Fig. 363, 

 where the formative radicles of the intra-insular hepatic vein is 

 seen in the centre, and the capillary communications on the other 

 hand with the vena portae, in the perimetral portion. The latter, 

 however, even in the pig, does not form a complete ring round each 

 lobule. The blood probably moves more slowly in the outer part 

 of the capillary network ; where it is more richly charged with the 

 constituents of the bile. The external cells also usually contain 

 the most fat ; the central the most colored granules. 



The hepatic artery also terminates in the outer part of the capil- 

 lary plexus of each islet, with the vena portaB, it having previously 

 supplied the walls of the vessels, and the intra-insular spaces (the 

 capsules of the lobules, in the pig). In regard to the lymphatics and 

 nerves of the liver, the works on descriptive anatomy may be con- 

 sulted. That some twigs from the diaphragmatic nerve are sent 

 to this organ, was first announced by Luschka. 



Dr. Beale finds the chemical composition of the liver to be as fol- 

 lows : 



Water 68.58 



Solid residue 31.42 



