360 THE METABOLISM OF THE CARBOHYDRATES 



By comparing these figures, it will be seen that far more sugar 

 had been formed in the phloridzin cats than could possibly have 

 come from the glycogen stored in their tissues, taking as an 

 estimate of this the amount found in the normal cats. 1 



To determine whether the cause of the appearance of sugar 

 in the urine in phloridzin diabetes is the same as in pancreatic 

 diabetes, let us further compare the two conditions. 



Although the obtaining of a similar D : N ratio suggests a 

 possible common cause for the glycosuria in the two conditions, 

 we shall see that such is far from being the case. At the same 

 time this constant ratio shows us that a maximal diabetic state 

 exists during which we can compare this form of diabetes with the 

 others. Let us, first of all, see whether the organism has lost the 

 power of destroying dextrose. We saw, in connection with pan- 

 creatic diabetes, that this question could be readily solved by ad- 

 ministering a measured quantity of dextrose, and seeing how 

 much of it reappeared in the urine. If 20 grm. of dextrose be 

 given to rabbits rendered diabetic to the maximal extent by 

 phloridzin, only a certain proportion of the dextrose will re- 

 appear in the urine, but, coincidentally, the nitrogen excretion will 

 fall, and the result on the D : N quotient will be a rise (to about 

 7). In dogs it is usually stated that the larger proportion of 

 the administered dextrose does reappear in the urine, but not 

 to the full extent. 



That only a proportion of the administered dextrose reappears 

 in the urine shows us that in phloridzin diabetes the organism 

 has not lost the power of utilising dextrose to the same extent 

 as in pancreatic diabetes or in Diabetes mellitus (see p. 367) ; it 

 shows us that the diabetes must be due to quite another cause. 

 The fall in the excretion of nitrogen is another indication that 

 the dextrose has been utilised by the tissues, and has so spared 

 the proteid metabolism. Similar results are obtained when the 

 other sugars are investigated in this way. 2 Lsevulose reappears 

 to a small extent partly as such and partly as dextrose, and the 

 nitrogen excretion falls slightly, but the greater proportion of the 



1 It will also be noticed that when alanin (amido-propionic acid) was given 

 to the phloridzin cats a larger amount of sugar than otherwise was excreted. 

 This important result we will return to later. 



2 To obtain the average sugar excretion for the days on which the sugar 

 in question is fed, the nitrogen excretion on these days should be multiplied 

 by 2-8. 



