CHAP, iv.] METABOLIC PROCESSES OF THE BODY. 587 



(see 339) though not an actual constituent of any of the 

 tissues must certainly arise in tissue metabolism, we may con- 

 clude 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 absorp- 

 tion of the glycin and taurin respectively. From which we may 

 conclude that the presence of these bodies stirs up the hepatic 

 cell to an increased formation of cholalic acid. 



378. 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 constitu- 

 ents. But there are some facts which seem to shew that the 

 two actions may be dissociated. 



The condition or symptom known as c 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 reab- 

 sorbed from the bile ducts, see 217. But in certain cases 

 where jaundice is a prominent symptom, no evidence of any 

 obstruction whatever 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 accumulation in 

 the blood or elsewhere of bile acids though there is of bile pig- 

 ment. And in the obscure malady known as simple or idiopathic 

 jaundice, in which though the anatomical conditions are unknown 

 there is at least no sign of obstruction, the urine though loaded 

 with bile pigment is said to contain no bile acids. 



379. The question may be asked, Is the secretion of bile 

 independent of or in some way or other connected with the 

 glycogenic activity of the cells ? To this we cannot at present 



