294 GENERAL ANATOMY. 



who distinguished them very well, placed the origin of the 

 former in the liver. The difference and connexion between 

 the arteries and veins have been perfectly established by the 

 discovery of the circulation of the blood ; since that time, the 

 study of the venous system has been somewhat neglected.* 



439. The veins, like all the vascular system, have an ar- 

 borescent disposition ; but considered with respect to the di- 

 rection of the course of the blood, they rather resemble the 

 roots of a tree, than its branches. Thus their origin takes 

 place by radicles, which correspond to the ramuscules of the 

 arteries; their termination by trunks which open into the 

 heart, like the origin of the arteries; their course presents re- 

 unions and successive divisions, like that of the arteries. If 

 examined then, by following the course of the blood, they 

 present a contrary disposition to that of the arteries; and if 

 considered in the same direction as the arteries, we should 

 follow a course opposite to that of the blood. 



440. The venous system, like the arterial, is double; the 

 one general, returns the blood of the body to the anterior or 

 right auricle; the other brings back the blood from the lungs 

 to the other auricle of the heart. There is moreover a parti- 

 cular and complicated venous system in the abdomen: this is 

 the vena porta, the disposition of which must be the object of 

 a separate investigation. 



441. This particular venous system constitutes of itself a 

 whole vascular system, that is to say, a tree having a trunk, 

 roots and branches, placed between the last ramuscules of the 

 gastric, intestinal and splenic arteries, which are continuous 

 with its roots, and the first radicles of the sub-hepatic veins, 

 which are the continuation of its branches. This vascular 

 system, if we take into consideration its disposition, which is 

 ramified in opposite directions, resembles the veins in its in- 

 testinal half, and the arteries in its hepatic half; under another 

 relation, it is indifferent to both, being intermediate, for it is 

 at the point where it is the continuation of the arteries, that it 

 has the venous disposition and vice versa. This vascular 



* Since our author wrote this passage, M. Breschet is publishing a most 

 splendid work on the venous system; which see. TRANS. 



