THE METABOLIS Id OP 1 HE I &RBOHYDBATE8 



the therapy of diabetes makes it advisable for us to go into the subject 

 a little more in detail here. 



Dogs are rendered diabetic by phlorhizin after a cold bath and 

 exposure in a cold room. When all of the original glycogen in the 

 body lias been go1 rid of, as evidenced by the constancy of the l > to N 

 ratio in the daily quantities of urine excreted, the Bubstance under in- 

 vestigation is fed. It' this substance contains no nitrogen and causes no 

 change in the nitrogen excretion, any increase in thai of glucose must 

 obviously represenl the extenl to which the substance has become con- 

 verted into this sugar. On the other hand, it' the Bubstance itself con- 

 tains nitrogen, or if it causes a change in the excretion of nitrogen, it 

 becomes necessary to calculate how much of the excreted glucose may 

 have been derived from the body protein, assuming that this can form 

 glucose, and how much from the administered substance.* 



Prom the results of this method it lias been an easy matter to show 

 that the following substances are converted in the animal body into 

 glucose: (1) Glycol aldehydi CH 2 OB CHO). By placing three mol- 

 ecules of this substance together, a hexose molecule results, a syntht 

 which can be accomplished in the chemical laboratory. The hexose formed 

 in the animal body is glucose. Glycol aldehyde may be formed in normal 

 metabolisi it of glycocoll <UI Nil COOB . 



(2) Glycerol (CH 2 0B CHOB < II "II may also readily he con- 

 verted into hexose in the laboratory, the -possible intermediary prod 

 being dioxyacetone (CH 2 0B < '< » CH 2 OB and glyceric aldehyde 

 CH a OB CHOB CHO). Two molecules of either of these may be 

 polymerized to form a hexose molecule, and when this process occurs 

 in the animal body, the hexose formed is glucosi 



3 Lactic acid (CB CHOB COOB is completely i verted to glu- 

 cose in the diabetic animal, and the pr ss must involve both a re- 



arrangemenl of the molecule and subsequent polymerization. The relat 

 substance, propyl alcohol (CB CH, CH 2 OB is also converted 

 glucose in the phlorhizinized d< g. As to the exacl nature of the chemical 

 changes which occur as intermediary steps iii the conversion of t ; 

 substances into glucose, we are nol as yel certain, hut a clue has 

 been afforded by the discover} that a sul>si;inee called methylglyoxal 



• II COCHO can I btained from lactic acid ami also from glucose, ami 



that this substance is converted into glucose when it is administered to phlor- 

 hizinizcd do>_ r s. We shall find later an importanl role for this substance 



riiis 



dedu the nit: lie differ . ;i of the 



body pro 

 which tin- sul 



niitiK fi then he ascert.v 



from the t>>- on. 



