CARBOHYDRATES. 79 



urine also comes from other organs. The experiments of Moos 1 and of Moritz 

 Schiff 2 have proved that only the sugar formation in the liver is affected. 

 If the vessels of the liver are all tied, the diabetic puncture becomes 

 inoperative. This is particularly well shown by the experiments of Schiff, 

 who took eight frogs of the same size, and produced glucosuria in all of 

 them. At the end of from two to four and three-quarters hours sugar 

 could be detected in the urine. The livers of all the animals experimented 

 upon were then exposed, drawn out through the abdominal wound, and 

 all the vessels and bile ducts encircled with a slip-knot of thread. In 

 four cases the knots were drawn tight, while in the other four they were 

 not. In the latter case the glucosuria continued, while in the former it 

 gradually diminished, so that at the end of three hours the urine was free 

 from sugar. 



It is not yet clear how this increased sugar formation is brought about. 

 There are several conceivable possibilities. The fact that the glycogen 

 stored up in the liver is suddenly converted into glucose, would make it 

 seem probable that the diastatic action has been considerably increased 

 above the normal. It is also conceivable that there is an increased pro- 

 duction of diastase, or, on the other hand, it is possible that under 

 normal conditions the glycogen is not, as ordinaly assumed, deposited in 

 the cells as a foreign body, but rather in the form of a loose chemical 

 combination, and that the diastase begins to act upon glycogen as soon 

 as it is set free. By exerting certain influences upon the liver cells, - 

 whether by the diabetic puncture, or whether by some other excitement 

 of the sugar center, all of the glycogen is perhaps set free from its 

 loose chemical combination, and subjected to the action of diastase, which 

 found no point of attack as long as the glycogen was in a combined 

 state. Claude Bernard believed that the increased formation of glucose 

 was due to an increased blood flow, which was probably caused by the 

 fact that the diabetic puncture had an effect upon the vaso-motor center. 

 He had in mind the increased blood flow which accompanies the increased 

 secretion of saliva by the submaxillary 3 gland on stimulating the fibers 

 in the chorda tympani. R. Heidenhain, however, has shown that an 

 increased secretion of saliva may take place without an increase in the 

 blood flow, and that the chorda tympani evidently possesses certain specific 

 secretory fibers. Analogously, it is possible that the splanchnic nerves 

 contain fibers which exert an influence upon the formation of glucose in 

 the liver. 



Closely connected with the so-called " diabetic puncture " we have 

 another observation to consider. If a one per cent, solution of common 



1 Arch, wissenschaftl. Heilkunde, 4, 37. 



J Untersuchungen liber die Zuckerbildung in der Leber, p. 76, Wiirzburg, 1859. 



3 Pfliiger's Arch. 6, 309 (1872); 9, 335 (1874). 



