92 6 METABOLISM. 
activity of the muscular tissue ; and accordingly anything, such as the 
sudden application of heat, able to instantly kill the liver cells stops 
such change. 1 On the other hand, it may also be that the trans- 
formation is caused by an amylolytic ferment, which is produced by 
the cells. This view was in fact held by Bernard, 2 but he afterwards 
supposed that the ferment was derived from the blood. 3 
It has been denied that such a ferment can be obtained from the liver, and 
it has therefore been contended that the transformation of glycogen into sugar 
must be produced by the direct metabolic action of the cell protoplasm. It 
has also been argued that, since the sugar which is produced by the digestive 
amylolytic ferments is maltose, and not dextrose, the production of dextrose in 
the surviving liver cannot be due to a ferment. Pavy, however, has shown 
that an active amylolytic ferment is obtainable from the alcohol hardened 
liver both in rabbits and cats, and that the sugar which is produced by it is 
closely similar to, if not identical with, that formed in the " surviving " organ. 4 
A ferment converting glycogen into dextrose has also been obtained from 
the liver by Arthus and Huber, 5 and by Bial, 6 who states that it is identical 
with and probably derived from the diastatic ferment of blood and lymph. 7 
Puncture diabetes. — Bernard 8 also discovered the fact that certain 
lesions of the central nervous system, and especially a puncture in the 
region of the floor of the fourth ventricle, which corresponds, as we now 
know, very nearly to the position of the vasomotor centre, produces a con- 
dition of glycosuria ; and that this is caused by a transformation of the 
glycogen of the liver into sugar, which is then taken up by the hepatic 
veins in so considerable a quantity, and increases so much the percentage 
of sugar in the blood, as to cause its excretion by the kidney. That this 
is the origin of the sugar in the so-called " puncture diabetes," is proved 
by the fact that, if precautions are taken to render the liver devoid of 
glycogen, as by a prolonged period of inanition, 9 with or without severe 
muscular activity, the glycosuria ordinarily resulting from puncture of 
the fourth ventricle does not appear, nor does it occur in frogs with the 
liver removed. It has been conjectured, with much probability, that 
1 Noel Paton found that if the liver substance be bruised up in a mortar with sand, so as 
to crush and thus destroy the liver cells, the change of glycogen into sugar does not occur 
{Phil. Trans., London, 1894, vol. clxxxi. p. 233). But a repetition of his experiments by 
Pavy ("Epicriticism," London, 1895. p. 79) has not yielded the same results, and, since 
they were only few in number, they can hardly be accepted without further confirmation. 
Paton has, moreover, in later experiments, himself failed to verify his earlier results 
(Journ. Physiol., Cambridge and London, 1897, vol. xxii. p. 121). 
2 " Lecons sur le diabete," Paris, 1877. 
3 Compt. rend. Acad. d. sc, Paris, tome xli. p. 461. 
4 There seems to be little doubt that this sugar is mainly if not entirely dextrose 
(Seegen and Kratschmer, Arch. f. d. gcs. Physiol., Bonn, 1880, Bd. xxii. S. 214), but 
according to Chittenden and Lambert {Stud. Lab. Physiol. Chcm., New Haven, 1S85) 
there is some maltose. Kiilz and Yogel also found a certain amount of both maltose 
and isomaltose in the fresh liver {C'cntralbl. f. d. vied. Wisscnsch., Berlin, 1894, S. 769). 
The remark that has been already made regarding the sugar found in blood applies to all 
these determinations of liver sugar, namely, that what is actually determined is the 
amount of reduction of cupric oxide, and that there may be, and undoubtedly are, other 
substances present besides sugar which effect this reduction. 
5 Arch, de physiol. norm, ct path., Paris, 1892, p. 651. 
6 Arch./, d. gcs. Physiol., Bonn, 1893, Bd. lv. S. 434. 
7 See article "Blood," p. 160. 
8 "Lecons sur la physiol. et la pathol. du systeme nerveux," Paris, 1858, tome i. p. 
401. See also Eckhard, Bcitr. z. Anat. u. Physiol. {Eckhard), Giessen, 1869, Bd. iv. S. i. 
Kiihne found the same thing to happen in frogs (Inaug. Diss., Gottingen, 1856). 
9 Luch singer, loc. cit. 
