THE RENI'PORTAL VEIN, 37 



Veins, turning dorsally a short distance behind 

 the heart, and entering the peritoneal cavity. 

 Joining each, just at this point, is a vein from 

 the pectoral region, and uniting them in front 

 of the pelvis, and also behind the heart, are 

 cross-branches ; that behind thp heart will be 

 seen to receive small pericardiac branches. 



c. Posteriorly, note the formation of each an- 

 terior abdominal vein by the union of a small 

 branch, running from the ventral aspect of the 

 pelvis, with a larger vessel appearing at its 

 outer side ; the former results from the division 

 of a single larger median vein, which, when 

 traced back, is seen to be formed by the union 

 of two lateral trunks with a median one ; these 

 all carry back some blood from the tail, and 

 from the ventral regions of the pelvic girdle. 



d. Trace back the outer branch entering into the 

 anterior abdominal trunk ; on the muscles 

 covering the ilium it is joined by a large vein 

 from the hind limb ; this, t\\Q femoral vein,h.QYQ 

 divides into the trunk just described which 

 enters the anterior abdominal, and another, 

 the reiii-portal vein, which turns dorsally. 



80. If proper care has been taken in the previous dis- 

 section the veins will be filled with blood and easily 

 traced ; if they are empty they collapse, and are hard 

 to follow, and their relative sizes are also impossible to 

 appreciate. If this be so, cut a hole in one of the 

 smaller branches ; take a fine blow-pipe, and direct a 

 current of air on the vessel till it strikes the aperture 

 and distends it, so that it is readily seen ; then put in 



