Dissection of Common Rat 187 



centre of the Membrane. Next, let him turn over the Intes- 

 tines on the right of the body, and trace the first three inches 

 of the Small Intestine after leaving the Pylorus, laying it out 

 on the left, towards the tail ; by this means a light white 

 cord is seen, to the right, which would seem to prevent the 

 complete extension of the Intestine in the direction indicated, 

 and which appears to issue from the right centre of the dorsal 

 margin of the Liver. The white cord is the Bile duct, which 

 enters the Intestine about two inches from the Pylorus. 

 Between the Bile duct and the Intestine is stretched a process 

 of Omentum in which a further portion of the diifused Pancreas 

 is visible. This low dendritic type of gland prevails in Roden- 

 tia : here the main part of the gland is that which extends 

 from the end of the duodenal fold to the left, into the gastro- 

 splenic omentum, where it ramifies : the chief part of the 

 duodenal Pancreas following the curve of the gut, but rami- 

 fying in its wide mesentery. In these creatures the Pancre- 

 atic ducts are many in number, and paired ; not single, as is 

 usually the case in Man. This may be readily demonstrated 

 by means of injection. Having tied one end of the Hepatic 

 duct, inject a cold blue injection into the other end, and it will 

 run, on either side, into the many Pancreatic ducts. If this 

 last portion of Intestine, Pancreas, and Bile-duct, be now 

 turned over to the right front, the spleen remaining as it was 

 left above, viz., over the left thigh, a little way from the 

 stomach, the student will be able to trace the principal 

 factors of the Portal vein, viz.: the Splenic coming from the 

 Spleen, the Mesenteric vein coming across from the centre of 

 the Mesentery, and both uniting at a spot in the median line 

 prior to entering the substance of the Liver just dorsad of the 

 Bile-duct. 



The Mesenteric Arteries (which supply the Intestines, and 

 arise from the Aorta just posterior to the Liver) and also the 

 Penal Arteries may be next traced. This will be best 



