318 SCIENCE PROGRESS. 



be given. "Vital action," as distinguished from ferment 

 action, is generally a dehydration ; as examples one may 

 take the formation of albumin from peptone by the intesti- 

 nal epithelium, or the formation of glycogen from sugar by 

 the liver cells. In the present state of our knowledge, or 

 rather of our ienorance, it is unwise, however, to limit the 

 term " vital action " to processes of dehydration and to 

 assume that a hydration must of necessity be produced by 

 a ferment, and that the metabolic activity of cells cannot 

 bring about hydration as well as dehydration without the 

 intermediation of an enzyme. 



If we assume with Paton, Ransom and others that in 

 the liver cells vital action will explain the origin of sugar 

 from glycogen, the question next arises whether it is pos- 

 sible to give any other example where living cells produce 

 a hydrating action. There is one other example which 

 appears to be very similar, and that is the formation of glu- 

 cose from maltose in the intestine. The experiments of 

 Dr. Shore and Miss Tebb (u) indicate that this change 

 cannot be wholly explained as clue to the activity of the 

 inverting ferment of the intestinal juice, but that the vital 

 action of the absorptive epithelium forms a factor in the 

 phenomenon also. 



We have seen that the ordinary source of the liver 

 glycogen is the carbohydrate of the diet ; but that it may 

 originate from proteid under certain circumstances. We 

 have seen also that the ordinary source of the sugar of the 

 blood is the glycogen of the liver ; it is necessary in con- 

 clusion to point out that sugar may also originate from the 

 proteid of the liver cells ; and here it must certainly be pro- 

 duced by metabolic or vital activity. There are certain 

 forms of diabetes which are entirely uninfluenced by diet ; 

 the patient passes as much sugar when he takes no carbo- 

 hydrate as when he is on starchy food ; and this form of 

 diabetes can be produced artificially. If the drug phloridzin 

 is given to an animal it becomes intensely diabetic. The 

 sugar might under these circumstances have a threefold 

 origin. It might come from the drug given, for phloridzin is 

 a glucoside. But the sugar passed is far in excess of that 



