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FORMATION OF GLYCOGEN. 397
body is difficult to answer for the present, as but little is known of the
quantity of these substances in the body, and our knowledge of the amount
of carbohydrate which can be split off from the various protein substances
is also very meager.
If the proteins are to be counted, and this is in agreement with the
generally accepted view, among those bodies which increase the glycogen
of the body, then Ave must ask the question: Do the proteins act only
indirectly as pseudoglycogen-formers, or are they direct glycogen-
formers which can serve as material for the formation of glycogen or
sugar? This question stands in close relation to the sugar formation
and sugar elimination in the various forms of glycosuria, and will be best
discussed below in connection with the question of diabetes.
Glycogen is a reserve-food deposited, in the liver and which, like other
carbohydrates can be transformed into fat, and it is generally admitted
that such a fat formation from glycogen also takes place in the liver.
There is no doubt that the glycogen deposited in the liver is formed in
the liver-cells from the sugar; but where does the glycogen existing in
the other organs, such as the muscles, originate? Is the glycogen of the
muscles formed on the spot cr is it transmitted to the muscles by the blood?
These questions cannot at present be answered with certainty, and the
investigations on this subject by different experimenters have given
varying results. The experiments of Iyulz, 1
in which he studied the
glycogen formation by passing blood containing cane-sugar through
the muscle, have led to no conclusive results, while the perfusion exper-
iments of Hatcher and Wolff with glucose seem to indicate a glycogen
formation from sugar in the muscles. The investigations of de Filippi 2
on dogs with so-called Eck’s fistula also show a glycogen formation from
sugar in the muscles. In the Eck fistula operation the portal vein is
ligated near the liver hilus and sewed to the inferior vena cava and an
opening established between the two veins so that the portal blood flows
directly into the vena cava without passing through the liver. In
well-nourished animals, operated upon in this manner, the livers had the
same properties as those from starving animals, while, on the contrary,
the muscles contained quantities of glycogen which corresponded to
those found in a normal over-fed dog.
If it be true that the blood and lymph contain a diastatic enzyme
which transforms glycogen into sugar, and also that the glycogen regularly
occurs in the form-elements and is not dissolved in the fluids, it seems
probable that the glycogen in solution is not transmitted by the blood to
1
See Minkowski and Laves, Arch. f. exp. Path. u. Pharra., 23; Kiilz, Zeitschr. f.
Biologie, 27; Hatcher and Wolff, Journ. of Biol. Chern., 3.
2
Zeitschr. f. Biol., 49 and 50.
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