105 



This nanle of venaportx is given to a peculiar venous system, enclosed 

 in the abdominal cavity, and formed as follows: The veins which bring 

 back the blood of the spleen, and the pancreas, of the stomach and intes- 

 tinal canal, are united in a very large trunk, which ascends towards the 

 concave face of the liver, and there divides into two" branches*. These 

 lie in a deep fissure in the substance of this viscus; they send out, 

 through all its thickness, a multitude of branches, which divide like ar- 

 terial vessels, and end, in part, by opening into the biliary ducts or pores, 

 and, in part, by producing the simple hepatic veins. These veins, situ- 

 ated chiefly towards the convex or upper surface of the liver, bring back, 

 into the course of the circulation, the blood which has not been employ- 

 ed in the formation of bile, and that which has not served to nourish the 

 substance of the liver: for^ they arise equally from the extremities of 

 the vena portae, and from the extremities of the ramifications of the he- 

 patic arteryf. 



The liver differs from all organs of secretion, in this, that the materi- 

 als of the fluid it elaborates, are not supplied to it by its arteries. It 

 should seem that the bile, a fat and oily fluid, in which hydrogen and car- 

 bon predominate, could be drawn only from venous blood, in which, as is 

 known, these two principles are in superabundance. The blood acquires 

 the venous qualities, as it passes along the circuitous course of the circu- 

 lation, and is supplied with hydrogen and carbon the more fully, the 

 slower it flows. Now, it is easy to see, that all is naturally disposed for 

 slackening the circulation of the hepatic blood, and to give it, eminently, 

 the distinguishing properties of venous blood. The arteries which fur- 

 rush blood to the organs, in whkh the vena portae rises, are either verv 

 flexuous as the splenic, or frequently anastomose, like the arteries of the 

 intestinal tube, which of all that are in the body, abound most in visible 

 divisions and anastomoses. It will be seen in the chapter on circula- 

 tion, how well these dispositions are adapted for retarding the course 

 of the arterial blood. Once carried into the organs of digestion, the 

 blood stays there, whether it be that the coats of the hollow viscera be- 

 ing collapsed or closed upon themselves, hardly yield it passage, or 

 that the organization of some one of these viscera is favourable to its 

 stagnation. 



The spleen seems to serve this purpose. Does this dingy and soft 

 viscus, lodged in the left hypocondrium, and attached to the great fundus 

 of the stomach, receive the blood into the minute cells of its spongy pa- 

 renchyma, or does this fluid merely traverse, very slowly, the delicate 

 and tortuous ramifications of the splenic vessels? In other respects, there 

 is no organ that exhibits more variety of number, of bulk, of figure, of 

 colour, and of consistence. Sometimes manifold, often divided into se- 



* Professor Louis JACOBSOX, has made a very important discovery in comparative ana- 

 tomy relative to a venous system going- to the kidneys, analogous" to the portal system 

 ofthe liver. A translation ofhis Observations has been published in the Philadelphia 

 Medical Journal, vol. 6, p. 87. We have satisfied ourselves of his con-ectness, espe- 

 cially by an examination of these veins in the sturgeon. Godman, 



In two instances the vena ports has been found running, not to the liver but di- 

 rectly to the vena cava inferior. One of these is described by Mr. AHERNETHT, in Vol. 

 LXXXI1I. of the Philosophical Transactions, and the other by Mr. LAWRENCE, in Vol. 

 IV. ofthe Medico-Chirurgical Transactions. Copland. 



For some observations on the structure and actions ofthe liver, see APPENDIX 

 M. 



