132 . SPECIAL HISTOLOGY. 



(Theile), which, in the Pig, divides between the hepatic islets, 

 in the capsules of the lobules, into fine anastomosing twigs, 

 and is directly connected with the peripheral part of the capil- 

 lary network of the hepatic islets or lobules, formed, as stated 

 above, by the portal vein. Arterial blood therefore takes a 

 part, although perhaps a minor one, in the preparation of the 

 bile and the hepatic artery is thus distinguished from the 

 bronchial arteries, whose blood is carried away by special 

 veins. 



The lymphatics of the liver are very numerous, and may be 

 divided into superficial networks, under the peritoneum; and 

 deep vessels, which accompany the uortal vein, and, in animals 

 at least, the hepatic veins also. Both kinds of vessels are 

 connected and proceed partly through the diaphragm into the 

 thorax, partly to small lymphatic glands in the porta hepatis 

 and to the intestinal plexus. The lymphatics of the gall- 

 bladder are also exceedingly numerous. 



The nerves of the liver are relatively very abundant. They 

 arise from the sympathetic and, in a smaller proportion, from 

 the vagus, and are chiefly distributed with the hepatic artery, 

 around which they form closer and wider networks without 

 ganglia. They always contain, together with many fine tubules 

 and ( Remak's fibres/ a few thick fibres, and may be traced: — 

 1. to the gall-bladder and large biliary ducts ; 2. in Glisson's 

 capsule, as far as the interlobular arteries, where their finest 

 twigs, of 0008 — 0010"', contain only nucleated fibres ; 3. to 

 the hepatic veins ; and lastly, 4. into the coats and ligaments 

 of the organ. 



§ 163. 



According to the latest observations, particularly of Bischoff 

 and Remak, the development of the liver may thus be best un- 

 derstood. The primary rudiment of the liver, which appears 

 at a very early period (about the 55 — 58 hour, in the Chick ; in 

 Mammals, after the Wolffian bodies and the allantois) consists 

 of two masses of cells, an external, proceeding from the fibrous 

 membrane of the intestine and an internal, epithelial, which 

 at first form a simple, and afterwards a dichotomously divided 

 sac. Solid processes, the hepatic cylinders of Remak, are now 

 developed from the epithelial lamina, which, as in the intestine, 



