DISEASES OF THE LIVER. 



chyma of the irritated organ ; this is usually accompanied by a diminu- 

 tion of resistance of the parenchyma. This diminution of resistance 

 must result in dilatation of the capillaries, and increased flow of blood 

 to the part. This explanation of the fact, " ubi irritatio ibi affluxus," 

 which is so apparent in the action of warmth on the skin, is here hypo- 

 thetical, it is true, but it is certainly that which best agrees with our 

 present knowledge of the subject. 



3. We are just as ignorant as to whether the cases of hyperaemia 

 of the liver from infection of the blood with miasm, particularly with 

 malaria, or those occurring so frequently in the tropics, depend on re- 

 laxation of the parenchyma, or whether they are due to paralysis of 

 the muscular fibres of the efferent blood-vessels, or to a textural change 

 of their walls, or how else they occur, as we are about the pathogeny 

 of the hyperaemias and textural changes in the other infectious dis- 

 eases. Among the cases of apparently fluxional hyperaemia of the 

 liver, for which we can give no full explanation, are those' which occur 

 in some women just before menstruation, and are particularly marked 

 in amenorrhcea. 



Congestion of the liver is far more frequent than fluxion ; all the blood 

 which flows from the liver through the hepatic vein has passed through 

 a double set of capillaries. (This is also true of the blood supplied by 

 the hepatic artery. The capillaries formed from the hepatic artery and 

 spreading out in the serous covering of the liver, and in its substance 

 between the vessels and bile-ducts, unite to small venous trunks, which 

 du not empty into the hepatic veins but into the portal veins, and, with 

 these, again break up into capillaries.) Hence the lateral pressure in 

 the hepatic veins is very slight. But the hepatic vein opens into the 

 vena cava at a point where, under normal circumstances, the flow of 

 blood meets proportionately no obstruction, as it can pour freely into 

 the empty auricle, and particularly since during each inspiration there 

 is a tendency of the blood toward the thorax. If there be a disturb- 

 ance of these very favorable conditions for the escape of the blood, if 

 the obstruction to its entrance from the hepatic vein into the vena cava 

 be increased, it collects in the liver. Only a slight obstruction is 

 accessary, for the lateral pressure in the hepatic vein is too insignifi- 

 cant to overcome even a very slight obstruction. 



According to what we have just said, the circumstances which induce 

 congestion of the liver are those which interfere with emptying of the 

 right auricle. Thus it occurs 



1. In all valvular diseases of the heart, it appears soonest in affec- 

 tions of the right side, later in those of the mitral, and latest of all n. 

 those of the aortic valves. The date of the appearance of congestion 

 of the liver in valvular disease depends, as we have previously fully 



