veral lobes by deep clefts; its bulk varies, not only in different individu- 

 als, but even in the same, at different times of the day, as the stomach, 

 full or empty, admits or rejects the arterial blood, and compresses the 

 spleen between its large extremity, and the ribs under which it is situa- 

 ted, or leaves it free. 



The blood which fills the tissue of the spleen, blacker, more fluid, rich- 

 er in oily principles, owes all these qualities, which led the ancients to 

 consider it as a peculiar substance, called by them the atra bilis, or black 

 bile, to its long protracted continuance within that viscus* The branches, 

 which by their union form the vena portse, have thinner parietes than 

 the other veins of the body, they are not furnished with valves, and they 

 do not readily free themselves of the blood which fills them. The action 

 of these veins is, in fact, so feeble, that it would not suffice to enable 

 them to carry the blood onward, if the gentle and alternate compression 

 of the diaphragm and abdominal muscles on the viscera of the abdomen, 

 did not favour its circulation. On reaching- the liver, the blood, which 

 is highly venous, is further slackened in its circulation, by the increased 

 dimensions of the space in which it is contained, the united calibre of 

 the branches of the hepatic vena portae, exceeding considerably that of 

 the principal trunk. Besides, these vessels are enveloped in the paren- 

 chymatous substance of the liver, and can act but feebly. It, therefore, 

 circulates slowly through that organ, and, with difficulty, returns into 

 the course of circulation. The hepatic veins, which are of rather con- 

 siderable calibre, and without valves, remain constantly open, their pa- 

 rietes cannot close and contract on tlie blood which fills them, on account 

 of their adhesion to the parenchymatoixs substance of the liver. They 

 open into the vena cava, very near the place' at which that vein termi- 

 nates in the right auricle. The regurgitation of the blood, during 

 the contraction of that cavity of the heart, is fek in the veins, and the 

 blood forced back towards the liver, is exposed for a longer time to 

 its action. 



The spleen, therefore, performs only preparatory functions, and may 

 he considered as the auxiliary of the liver, in the secretion of the bile*. 

 It is observed, that the quantity of the latter increases, after the spleen 

 has been extirpated, and that it is less yellow, less bitter, and always im- 

 perfect. The blood which circulates in the omentum, is very similar to 

 that of the spleen; I would even say, that it contains oily particles, if 

 the drops which I have clearly noticed on its surface, might not have 

 come from the adipose tissue of the omentum, which allows the fluid con- 

 tained in its cells to flow, when a small puncture is made into it, in exa- 

 mining the blood contained in its veins. 



The bile secreted in the tissue of the liver f is absorbed by the biliary 

 ducts, the union of which forms the hepatic duct. The latter issues from 

 the concave surface of the liver, and conveys the bile, either immediately 

 into the duodenum, by means of the ductus communis choledochus, or 

 into the gall bladder. This small membranous pouch, which adheres by 

 means of cellular tissue to the lower surface of the liver, is in some ani- 

 mals entirely distinct from that organ, and connected to it, only by the in- 



* On the subject of cystic and hepatic bile, the student will do well to consult BICHAT 

 on tJie membranes, p. 61, &c. Godman. 



j- See APPENDIX, Note N, for an account of the latest observations and opinions 

 respecting the structure and functions of the spleen. Copland. 



