238 THE SALAMANDER 



pass through the mesentery on the left side, and the branches of the 



mesenteric arteries on the right. 



The factors of the -portal vein, 



{a) The V. gastrico-lienalis (v.g.lien.) runs posteriorly through the 

 mesentery which suspends the spleen from the dorsal stomach-wall. It 

 is constituted by a series of tributaries, on the one side from the gland, 

 and on the other from the dorsal stomach-wall, and is the venous 

 counterpart of the lieno-gastric artery which runs more or less 

 parallel with the vein, between it and the stomach. 



Just before its junction with the mesenteric veins it gives off a 

 small branch which may be termed the minor portal vein. This 

 vessel passes along the postero-ventral side of the post-caval lobe of 

 the liver. 



As was the case with the arterial system it is not easy to differenti- 

 ate the anterior from the posterior mesenteric vessels. The following 

 arrangement seems to be the most satisfactory and convenient 

 generally. 



{U) The V. haemorrhoidalis (v.hm.) drains the blood from the dorsal 

 side of the rectum, and the extreme posterior end of the intestine. 

 A short distance before it unites with the lieno-gastric vein at the 

 origin of the portal vein it is frequently joined by the posterior intes- 

 tinal vein. 



{c) The V. intestinalis posterior (v.in.p.) is the largest of the three 

 intestinal veins. It returns the blood from the posterior two-thirds 

 of the intestine (excluding the rectum). It always enters the portal 

 vein in very close association with the haemorrhoidal vein, and as 

 already stated they frequently unite and enter as a single vessel. 



{d) and (<?) The middle and anterior intestinal veins. These two 

 factors enter the portal vein at intervals of about a millimetre along 

 its length. Their origin in the intestine is very restricted, and to- 

 gether they return the blood from the remaining third of the intestine 

 and the posterior end of the duodenum. There is much variation. 



(/) Rusconis vein (v.R.) (Hochstetter), or V. omphalo-mesenterica 

 sinistra (Choronshitzky). This vessel arises from numerous factors 

 in the duodenum and anterior part of the intestine, and passes cepha- 

 lad, parallel with the gut, to about the middle of the duodenum, 

 where it turns dorsalwards and enters the pancreas to join the pan- 

 creatic vein, the common trunk thus formed finally uniting with the 

 portal vein just before this vessel joins the abdominal vein. 



The vessel under consideration was first described by Rusconi, 

 who referred to it as the longitudinal vein of the gut, while its onto- 



