THE CIRCULATION THROUGH SPECIAL ORGANS 433 



fifth thoracic spinal nerves. Brodie and Dixon, ^ on the other hand, 

 deny their presence, and state that the excitation of the vagus or 

 sympathetic nerve does not cause a significant alteration in the rate 

 of perfusion through an isolated lung. Similar results have been ob- 

 tained by Burton-Opitz,^ who measured the blood flow in the pulmo- 

 nary artery with the aid of the stromuhr. The -use of adrenalin 

 has failed to decide this matter one way or another. In the hands of 

 the investigators just named, this agent has given negative results, 

 while Plumier^ has found that the flow through a perfused lung may be 

 diminished by adrenalin. A diminution in the flow is also said to 

 follow the stimulation of those sympathetic fibers which pass between 

 the first thoracic ganglion and the pulmonary plexus. It is conceded, 

 however, that the changes so obtained are slight and not absolutely 

 constant. This result serves as an argument against an active be- 

 havior of the pulmonary blood-vessels, because true vasomotor reac- 

 tions are always of an amplitude which makes the use of very delicate 

 means for their detection superfluous. 



C. THE PORTAL AND RENAL CIRCULATIONS 



The portal system embraces those abdominal organs which drain 

 their blood into the vena portse, a large venous tube formed by the 

 union of the vencB mesentericce and the vena gastroUenalis. Before this 

 channel enters the hilus of the liver it receives another vein of consider- 

 able size, namely the vena pancreatica. Centrally to the liver, the 

 blood is conducted into the inferior vena cava by the hepatic veins. 

 As the name indicates, the mesenteric veins return the blood from the 

 intestines, while the gastrolienalis collects it from the spleen and the 

 largest part (left) of the stomach. The remaining portions of this 

 organ, as well as the principal mass of the pancreas and the middle and 

 upper segments of the duodenum, are drained by the pancreatic vein. ^ 



The arterial supply of these organs is obtained first of all from the 

 celiac axis which divides into three branches, namely: (a) the hepatic 

 artery which supplies the framework of the liver, the body of the pan- 

 creas, and the adjacent portion of the duodenum, (h) the gastric artery 

 which ramifies upon the right expanse of the stomach, and (c) the 

 splenic artery which passes to the spleen, the cauda of the pancreas 

 and the neighboring left segment of the stomach. The intestine 

 receives its blood from the superior and inferior mesenteric arteries. 



The organs just enumerated are innervated, on the one hand, by 

 the vagi nerves and, on the other, by the greater and lesser splanchnic 

 nerves. The former terminate in the region of thegastro-esophageal 



1 Jour, of Physiol., xxx, 1904, 476. 



2 Proc. Soc. of Exp. Med. and Biology, 1904. 

 ^ Jour, de physiol. et de pathol. generale, vi, 1904. 

 ^ This description appHes to the dog. More complete data may be obtained 



)m EUenberger and Baum's Anatomie des Hundes, BerUn, 1891. 



28 



