88 LECTURE V. 



of sugar. Their necessary supply of carbohydrates is regulated by the 

 liver. It would seem possible, therefore, that the function of the liver 

 might be disturbed in some way by the removal of the pancreas. The 

 liver stores up the resorbed sugar in the form of glycogen. It might seem 

 possible that the liver in an animal deprived of the pancreas is no longer 

 able to retain the resorbed sugar, i.e., withdraw it from the general metab- 

 olism, so that in this way the blood is flooded with sugar. Now Pfliiger, as 

 we have seen, showed that the liver, even after long-continued glucosuria, is 

 still capable of forming glycogen. At least the ability is not entirely want- 

 ing. Furthermore, this assumption does not explain the fact that starving 

 animals also exhibit glucohemia. This latter fact suggests to us another 

 way in which the liver-function may be disturbed, namely, with regard to 

 the decomposition of glycogen. Hand in hand with the consumption of 

 sugar in the muscles, there takes place the transformation of the stored- 

 up glycogen into sugar. An extremely fine regulating mechanism pre- 

 vents large amounts of glycogen being suddenly decomposed in such a 

 way that the blood would be flooded with sugar. We have already met 

 with this regulation in discussing the glucosuria produced by the " diabetic 

 puncture," and the elimination of sugar in the urine caused by the injection 

 of salt solution into the circulation. We saw at that time how evident it 

 was that nervous influences had a great deal to do with keeping the glycogen 

 condition of the liver along definite paths. What is unexplained is merely how 

 the breaking down of the glycogen takes place. It is a result of diastatic 

 action. It is inexplicable why the diastase, which is evidently present in 

 the liver, at one time attacks the glycogen and at another leaves it alone, 

 unless we assume that either the glycogen is present in a condition such 

 that it cannot be acted upon by the ferment, i.e., is in some form of loose 

 chemical combination, or that the diastase becomes active only at the 

 time it is required. 1 We are acquainted with many ferments, as we shall 

 eventually see, which are secreted by the cells in an inactive condition. 

 In such cases the presence of another substance usually formed by 

 an entirely different kind of cells is necessary in order to make the 

 ferment " active." Such processes have not been sufficiently studied 

 in the case of diastase. We may assume, however, that by union with 

 some sort of substance, perhaps the protoplasm of the cells, the diastase 

 is inactive and becomes free only at such a time when it is needed. At 



1 The assumption that the breaking down and building up of glycogen takes place 

 in the same way that, for example, a hydrolysis or a synthesis may be brought about 

 artificially by the action of one and the same ferment according to the concentration 

 ratio (cf. p. 38) is not well established at present, for the products formed artificially 

 are not those expected, but their isomers ; and furthermore, it is not known that the living 

 cell contains the condition established in chemical experiments. Cf. Hofmeister's Die 

 Chemische Organisation des Zelle. Viewig and Sohn, Braunschweig, 1901. 



