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THE AMERICAN NATURALIST [Vol. XL 



main branch of the portal vein (P.) through which the blood finds 

 its way into the liver. The splenic vein, as its name would indi- 

 cate, collects blood from the spleen, but it brings blood also from 

 the middle region of the stomach. The greater part of the blood 

 from the stomach is collected into two well marked veins, the 

 superior and inferior gastrics (S. G., I. G.) which empty into 

 that part of the abdominal vein which has already been described 

 as extending for some distance along the ventral side of the liver. 

 Of these two gastric veins, the inferior is the larger, and empties 

 into the abdominal vein at some distance behind the superior 

 gastric. Emptying into the abdominal at almost the same place 

 with the inferior gastric, is a vein of considerable size, the pan- 

 creatic iPn.). The portal vein proper, then, brings blood to the 

 liver from the intestines and the spleen; but most of the blood 

 from tlie stomach and apparently all that from the pancreas is 

 carried into the liver through the abdominal vein. 



It now remains only to describe the system of the inferior vena 

 cava, and especially that part of the system that lies posterior to 

 the liver. The blood from the tail is collected into a caudal vein 

 (C.) that, after entering the abdominal cavity, becomes the in- 

 ferior or posterior vena cava (7. C.). This posterior part of the 

 inferior cava lies between and slightly ventral to the kidneys, and 

 is so closely associated with these organs, from which it receives 



almost lost. Extending along the distal sides of the kidneys, and 

 connected at frc(|iu'iit ii)tcrvals by small vessels with the inferior 

 cava, are the more or It-^s (li>tiiict veins of Jacobson (J. J\). Each 

 vein of Jacobson receives al)out six vertebral veins (F.) from the 

 corresponding side of the vertebral column. On account of the 

 great number of the renal veins and the close attachment to the 

 kidneys of the veins of Jacobson, the details of these veins are dif- 

 ficult to determine. 



'riic Mood from the reproductive ..rua US i\ einptie.l into the 



ends of these organs to reach the inferi..r cava. In the female, 



