FUNCTIONS OF THE LITER. 337 



secretion of bile, and from the purgative properties of ox- 

 gall. 



Nothing is known with certainty respecting the changes 

 which the re-absorbed portions of the bile undergo, either 

 in the intestines or in the absorbent vessels. That they 

 are much changed appears from the impossibility of de- 

 tecting them in the blood ; and that part of this change 

 is effected in the liver is probable from an experiment 

 of Magendie, who found that when he injected bile 

 into the portal vein a dog was unharmed, but was 

 killed when he injected the bile into one of the systemic 

 vessels. 



The secretion of bile, as already observed, is only one 

 of the purposes fulfilled by the liver. Another very im- 

 portant function appears to be that of so acting upon 

 certain constituents of the blood passing through it, as to 

 render some of them capable of assimilation with the 

 blood generally, and to prepare others for being duly 

 eliminated in the process of respiration. From the labours 

 of M. Bernard, to whom we owe most of what we know 

 on this subject, it appears that the low form of albuminous 

 matter, or albuminose, conveyed from the alimentary 

 canal by the blood of the portal vein, requires to be sub- 

 mitted to the influence of the liver before it can be assi- 

 milated by the blood ; for if such albuminous matter is 

 injected into the jugular vein, it speedily appears in the 

 urine ; but if introduced into the portal vein, and thus 

 allowed to traverse the liver, it is no longer ejected as a 

 foreign substance, but is probably incorporated with the 

 albuminous part of the blood. 



An important influence seems also to be exerted by the 

 liver upon the saccharine matters derived from the alimen- 

 tary canal. The chief purpose of the saccharine and 

 amylaceous principles of food is, probably, in relation to 

 respiration and the production of animal heat ; but in 

 order that they may fulfil this, their main office, it seems to 



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