INFL UENCE OF LIVER ON PR TEW ME TAB OLISM. 90 1 
stored within them for a time, passed on into the hepatic blood to reach 
the general circulation. There is, however, no clear evidence that such 
storage takes place in the liver, or that if it does the stored proteid 
undergoes any change within the liver cells. 
When we examine the secretion of the liver, we find that it contains 
a considerable amount of nitrogenous organic material (bile salts), in- 
cluding a certain amount of sulphur in organic combination (taurine). 
These nitrogenous and sulphur-containing materials can only be derived 
from proteicls, and since they are formed in greater amount during absorp- 
tion of digested products than at other times, it might well be supposed 
that they may be formed, at least in part, from the absorbed products 
of proteid digestion. As against this conjecture, we cannot, however, 
fail to notice that the appearance of these nitrogenous and sulphur- 
containing materials in the bile salts is accompanied by a considerable 
amount of material in the form of bile pigments, which can only be 
derived from the haemoglobin of the red blood corpuscles ; and since 
haemoglobin readily decomposes into hsematin, which is probably the 
part directly converted, with elimination of iron, into bile pigment, and 
a proteid or proteids, it has been conjectured, and with some pro- 
bability, that the bile acids are actually derived from this proteid part 
of the broken-down haemoglobin molecule. The only direct evidence 
that we have of the breaking-down of blood corpuscles within the liver 
is derived from certain enumeration experiments, which appear to show 
that the number of blood corpuscles per cubic millimetre passing to the 
liver is greater than the number per cubic millimetre in the blood flow- 
ing from the liver. 1 This by itself is not very strong evidence, but it 
becomes stronger when we remember that the blood flowing from the 
liver may be expected to contain less water than that which reaches 
the liver, since there has passed away from it the water of the bile 
and also a large amount of lymph. Moreover, the constant presence of 
lecithin and cholesterin in the bile may well be associated with the 
destruction of red blood corpuscles, which contain, relatively, consider- 
able amounts of these substances. 
While, therefore, the presence of the bile acids is a clear indication 
of the breaking-down of proteid in the liver, their presence does not 
necessarily indicate that such proteid is derived from the blood plasma, 
but it is, on the whole, more probable that it arises from the hamio- 
globin of blood corpuscles. 2 
The storage of glycogen in the liver, under circumstances when it 
can only be supposed to be formed from proteid, indicates another 
change which proteids may undergo in this organ. Such a formation 
of glycogen from proteid probably occurs hardly at all during absorption 
of a mixed meal, because the amount of carbohydrate absorbed from 
such a meal would be more than sufficient to account for the glycogen 
stored in the liver ; but, in the absence of carbohydrate from the food, 
the proteids may become so split up that one portion of the proteid 
becomes converted into urea, or into materials which ultimately form 
urea, and the other portion, possibly by becoming first somewhat 
broken clown and then again synthetised, into glycogen. 
A similar conjecture may be made with regard to the fat which is 
1 Nicolaides, Arch, de physiol. norm, etpath., Paris, 1882, p. 531. 
2 According to Kunkel, taurine may be formed from proteids in the tissues generally, 
and carried to the liver, Bcr. d. k. siichs. Gesellsch. d. Wissensch. , 1875. 
