CHAP, iv.] METABOLIC PROCESSES OF THE BODY. 783 



membering that taurin is found in several tissues, and that 

 glycin (see 419) though not an actual constituent of any of 

 the tissues must certainly arise in tissue metabolism, we may 

 conclude that the chief work in this respect of the hepatic 

 cell is to provide the cholalic acid, and to effect the combination 

 with glycin and taurin, though possibly some amount of either 

 one or the other of these bodies may be furnished by the 

 hepatic substance itself. As to how cholalic acid arises out of 

 the metabolism of the hepatic cell we know no more than we 

 do about the formation of kreatin in muscle or of pepsin in a 

 gastric cell. We are equally ignorant about the origin of glycin 

 and taurin, and cannot explain why in one animal glycocholic, 

 and in another taurocholic acid is prominent in the bile, though 

 the two bodies, as shewn especially by the presence of sulphur 

 in the taurin, are widely different. It has been observed 

 that the presence of bile in the intestine seems to excite the 

 liver to increased biliary action ; since the bile-acids are rapidly 

 changed in the intestine and the cholalic acid speedily altered, it 

 seems probable that the increased biliary activity is due to the 

 absorption of the glycin and taurin respectively. From which 

 we may conclude that the presence of these bodies stirs up the 

 hepa.tic cell to an increased formation of cholalic acid. 



480. As a general rule the formation of bile acids runs 

 parallel with the formation of bile pigment, an increase or de- 

 crease of bile meaning an increase or decrease of both constituents. 

 But there are some facts which seem to shew that the two 

 actions may be dissociated. The condition or symptom known as 

 'jaundice ' is essentially an excess of bilirubin in the blood, whereby 

 the tissues such as the skin, and the fluids such as the urine, are 

 coloured with the yellow pigment. In most of the maladies of which 

 jaundice is a symptom, there is evidence of an obstruction to the 

 flow of bile through the bile passages ; and the presence of bile in 

 the blood and hence in the tissues at large is in such cases due to 

 the fact that the bile after secretion by the hepatic cells is re- 

 absorbed from the bile ducts, see 256. In such cases bile acids 

 as well as bile pigment are generally, though not always, found in 

 the urine. 



But in certain cases where jaundice is a prominent symptom, 

 no evidence of any adequate obstruction to the flow of bile can be 

 obtained. This is the case in the jaundice of yellow fever and of 

 a peculiar allied malady known as ' acute yellow atrophy of the 

 liver.' Now in these cases there is no evidence of an accumu- 

 lation in the blood or elsewhere of bile-acids as there is of 

 bile-pigment. And in the obscure malady known as simple 

 or idiopathic jaundice, in which though the anatomical con- 

 ditions are unknown there is at least no obvious sign of 

 obstruction, the urine though loaded with bile pigment is said 

 to contain no bile acids. 



