448 PRACTICAL PHYSIOLOGY 



(2) By extirpation of the Pancreas. If the whole of the pancreas be 

 removed in dogs, glycosuria is at once established, and the blood will 

 be found to contain an excess of dextrose. So far, then, the cause of 

 the glycosuria is the same as in the previous condition, viz. an excess 

 of sugar in the blood. If, after the condition has existed several days, 

 the liver be examined it will be found to be glycogen-free, but, unlike 

 the previous condition, the glycosuria still continues, and in a few days 

 it will be noticed that the animal has become markedly emaciated. 

 The cause of the emaciation is that the protein tissues are undergoing 

 dissolution. That such is actually the case is proved by a determination 

 of the nitrogenous excretion, which will be found to be enormously 

 increased in amount. In the course of a few weeks the animal dies of 

 emaciation. 



These results show us that the pancreas must possess, besides its 

 digestive function, some controlling influence on the metabolism of 

 carbohydrates. 



(3) The administration of certain drugs, more especially of Phloridzin. 

 The administration of this drug is immediately followed by glycosuria, 

 which, however, ceases after a few hours. If the liver be examined at 

 this stage it will be found that a large proportion of its glycogen has 

 disappeared. If a second dose be administered the glycosuria will 

 reappear, and will persist so long as the drug is administered, and even 

 after all glycogen has been used up. After some time, however, the 

 animal becomes very emaciated, this being accompanied by an excessive 

 excretion of nitrogen. 



The percentage of sugar in the blood is normal, or even sub-normal. 

 On this account, it is supposed that phloridzin produces glycosuria by 

 disturbing the controlling mechanism of the kidney, whereby the latter 

 allows too much dextrose to escape into the urine, in consequence of 

 which the percentage tends to become sub-normal in the blood. 

 Increased demands are therefore made on the stored-up glycogen, 

 which at last becomes used up, and then the supply has to be 

 furnished by the proteins, and these break down. 



In both pancreatic and phloridzin diabetes, therefore, protein is an 

 important source of the excess of dextrose. It has been conclusively 

 shown now that it is from the amino acids, etc., that some of the 

 dextrose is derived. 1 



The other sugars which the urine may contain are lactose and 

 pentose. The former of these is sometimes found in the urine of 

 nursing mothers, and the latter appears in the urine whenever 

 pentoses (Wood Sugars, p. 294) are given in the food. 

 1 The conversion of fat into glucose is also possible. 



