280 SECRETION OF BILE. [BOOK n. 



as we shall see later on, take an active part in other operations of 

 even greater importance. The consideration of the question in 

 what way these several functions of the hepatic cells are related to 

 each other must be deferred for the present. 



In the third place, even if we maintain that the chief constitu- 

 ents of the bile are manufactured in the hepatic cells, and not 

 simply drained off from the blood, we are not thereby precluded 

 from admitting that the hepatic cells may avail themselves of 

 certain half-made materials, the arrival of which in the blood may, 

 so to speak, lighten their labours, or that they may even boldly seize 

 upon and pass off as their own handiwork any wholly manufactured 

 constituents which may be offered to them. Thus we have already 

 seen reasons for thinking that the bile-pigments are not made de novo 

 in the hepatic cells, but spring from haemoglobin, the change in the 

 liver being one of comparatively simple transformation. So also it is 

 quite possible, though not proved, that much if not all of the choles- 

 terin of bile is merely withdrawn by the liver from the body at large. 

 And even with the central components of bile, the bile-salts, we know 

 that in the case of taurocholic acid, taurin is normally present in 

 certain tissues, and that in the case of glycocholic acid, glycin, if not 

 a normal constituent of any tissue, is present in the body, since the 

 body can convert benzoic into hippuric acid, as we shall see in a 

 succeeding section ; so that the formation of these bodies by the 

 hepatic cells may be limited to the production of cholalic acid and 

 its conjugation with one or other of the above amido-acids. More- 

 over as a matter of fact, we find that the flow of bile from a biliary 

 fistula is much increased by the injection of bile into the small 

 intestine. This experiment renders it possible that some of the 

 bile which in natural digestion is poured into the intestine is re- 

 absorbed, and carried back to the liver to do duty over again. 



In medical practice, distinction is drawn between jaundice by 

 suppression of the secreting functions of the liver and jaundice by 

 retention, brought about by an obstruction existing in some part of 

 the biliary passages. The gravity of the symptoms in the first class 

 of cases shews that an arrest or a too great diminution of the 

 normal functions of the hepatic cells is at least accompanied by the 

 presence in the blood of substances injurious to life ; but how far 

 the presence of those substances is due to a failure of the manufac- 

 ture of bile and the accumulation in the system of the materials for 

 the formation of bile, or to a failure of other functions of the hepatic 

 cells, must be regarded as at present undetermined. The presence 

 of the bile-pigment in this form of jaundice would seem to indicate 

 that the formation of the pigment, i. e. the transformation of haemo- 

 globin into bilirubin, in contrast to the formation of bile acids, re- 

 quires but little labour on the part of the cell, and may be carried 

 on even when the nutrition of the cell is highly deranged. 



