926 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 f?rment. 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 " Le9ons 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. ges. Physiol., Bonn, 1880, Bd. xxii. S. 214), but 

 according to Chittenden and Lambert (Stud. Lab. Physiol. Chem., New Haven, 1885) 

 there is some maltose. Kiilz arid Vogel also found a certain amount of both maltose 

 and isomaltose in the fresh liver (Centralbl. f. d. med. Wissensch., 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, etpath., Paris, 1892, p. 651. 



6 Arch.f. d. ges. Physiol., Bonn, 1893, Bd. Iv. S. 434. 



7 See article " Blood," p. 160. 



8 " Le9ons sur la physiol. et la pathol. du systeme nerveux," Paris, 1858, tome i. p. 

 401. See also Eckhard, Beitr. 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. 



