358 THE METABOLISM OF THE CARBOHYDRATES 



produced in dogs by the administration of phloridzin. This drug is 

 a glucoside containing 38' 1 per cent, of dextrose which can be split 

 off from it by boiling with acids. The substance which remains 

 after splitting of! the dextrose is called phloretin. 



If phloridzin be given by mouth to an animal (dog, rabbit, 

 goose, &c.) in the dosage of 1 grm. per kilogr. body weight, glycosuria 

 becomes established in a few hours, the percentage of sugar in the 

 urine sometimes rising as high as 19-1. The glycosuria lasts for 

 a few hours and then passes off, unless the drug be re administered. 

 The drug may also be injected subcutaneously (O3-0'5 g:m. per 

 kilo body weight dissolved in warm water or in water made 

 faintly alkaline with carbonate of soda), and this method is the 

 more convenient when rabbits are under investigation. 



In well-fed animals the amount of sugar excreted varies con- 

 siderably, and the D : N ratio is very inconstant. During starva- 

 tion, on the other hand, the sugar excretion becomes less but at 

 the same time more constant, and there is a rise in the nitrogen ex- 

 cretion so that the D : N ratio comes to be the same as that found 

 in pancreatic diabetes when no food or only flesh food is given. 

 To obtain this constant D : N ratio certain points must, however, 

 be borne in mind. The ratio obtained on the first day after 

 the administration of the drug must be discarded, for it is always 

 above the average which is subsequently obtained. The explana- 

 tion given by Lusk and others of this higher initial quotient is 

 that the first effect of the drug is to cause an excretion of a la:ge 

 part of the free sugar of the blood. Even when several days' 

 starvation has preceded the administration of the phloridzin the 

 same thing is seen. The following table, adapted from Lusk ( 24 ), will 

 demonstrate this : 



TABLE VI 



The amount of sugar excreted does not depend, within wide limits, 

 on the dose of phloridzin injected, provided enough of the drug be 



