222 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



anastomosis with the ventral branch of the gastric vein, Gv., 

 PI. 11. 



From the median line of the abdominal wall the hepatic por- 

 tal receives from twelve to fifteen veins. Each of these veins is 

 formed by two branches which, coming from either side in the 

 septa of the abdominal muscles, unite at the mid-ventral line. 

 These veins run from the body wall to the liver in the ventral 

 mesentery, in which they often form an open network, each ves- 

 sel being joined by a transverse branch, or they may unite so that 

 not more than seven or eight veins enter the liver. Within the 

 liver they join, as has been said, the branches of the hepatic por- 

 tal. 



All the blood which is brought to the liver by the hepatic por- 

 tal and abdominal veins is collected by the Hepatic Veins, H., 

 PI. 11, which emj)ty into the postcaval vein at different points 

 along its course through the liver. The hepatic veins vary 

 greatly in size and have no fixed point of entrance into the post- 

 caval. Two of the hepatic veins are much larger than the others 

 and have a fairly constant point of union with the postcaval. 

 The larger of these two veins arises at the posterior end of the 

 liver and joins the postcaval near the center of the liver. The 

 other is not as constant in its course or place of origin; in the 

 majority of the specimens examined it took its origin near the 

 posterior border of the liver and ran along the left margin of the 

 liver, receiving many small branches, and finally united wdth 

 the postcaval at the anterior end of the liver. The first of these 

 two hepatic veins is shown in PI. 11, but for the sake of clearness 

 the last is omitted. 



SYSTEMIC VEINS. 



The PosTEEiOR Vena Cava, or Postcaval Vein, P. C, PI. 

 11, is the largest vein in the body; it runs anteriorly between 

 the kidneys receiving through the Venae Reheventes, V. Rev., 

 PI. 11, the blood which has been brought to these organs by 

 the venae advehentes, and a few veins from the muscles of the 

 back. Prom the kidneys it is continued just ventral to the 

 aorta until it is from 20 to 50 mm anterior to the posterior 



