102 J. LeConte—Glycogenic function of the Liver. 
quantities of sugar in the blood produce, among other hurtful 
effects, cataract and blindness. ‘The cataract, socommon amon 
diabetie patients is doubtless due to this cause. Plainly, there- 
fore, there is needed a reservoir to receive and detain the flood 
of glucose poured into the blood after every full meal of 
amyloids. The liver is that reservoir. A second reason for 
this double change—(and this is probably the fundamental rea- 
son)—is that the sugar is re-delivered to the blood not as glu- 
cose but as liver-sugar, and therefore in a more oxidable form— 
as a better fuel than previously. 
For thesake of greater clearness, we have spoken thus far as 
if glycogen were made only from sugar. Most of it is un- 
doubtedly made in this way in all animals except carnivora. 
But it seems certain that the liver has the power of making gly- 
cogen from albuminoids also; for animals fed on albuminoids 
alone still continue to make sugar from glycogen. Therefore— 
and this is a very important point—albuminoids are decompused 
in the liver into glycogen and some nitrogenous matter, which is 
separated and excreted partly in the bile, but probably mostly 
restored to the blood to be excreted as urea by the kidneys. 
In this way the excess of albuminoid food, over and above what 
is necessary for tissue-building is reduced to a condition suitable for 
easy combustion. 
But if this view be correct—if this be the way in which 
albuminoid food in excess of the requirements of tissue-build- 
ing is disposed of, then it is certain that waste tissues also are 
eliminated in the same way, for these are also albuminoid. 
The first step in the elimination of these takes place in the 
liver where they are decomposed into glycogen to be burned as 
sugar and eliminated through the lungs, and a nitrogenous res- 
idue to be eliminated mostly by the kidneys. If so, then ani- 
mals starved to death ought to make glycogen and liver-sugar 
to the last. Now, according to Chauvean, horses and dogs after 
six days fasting still continued to make liver-sugar.* 
Again: we have spoken thus far only of the dissolved food 
taken up by the portal capillaries and distributed through the 
liver before entering the general circulation. By far the larger 
part undoubtedly takes this course; but a small portion also is 
taken up by the lacteals. This enters the general circulation 
through the thoracic duct, little by little, in proportion as it is 
taken up. But this also must pass, though not so directly, 
through the liver by the hepatic artery or by the mesenteric 
artery and portal vein and is doubtless also arrested there in 
the form of glycogen. / 
There are, then, three sources of glycogen, and therefore of 
liver-sugar, viz: 1. The whole of the amyloid food. 2. All 
: . * Comptes Rendus, vol. xliii, p. 1008. 
