THE METABOLISM OF THE CABBOHTDSA1 681 



to the blood in the case of a completely diabetic animal, no chai 

 cms in the quotient. 



There are, therefore, two essential disturbances of carbohydrate 

 metabolism in pancreatic diabetes -overproduction ol r and aboli- 



tion of the ability of the tissues to ase it. It becomes important for us 

 to Bee whether the tissues exhibil this inability to us.- Bugar when t ; 

 are isolated from the animal; for if they Bhould, a much mo rching 



investigation of the essential cause of their inability would 1"' possible 

 than is the case when they are functioning along with the other organs 

 and tissues. The earlier experiments of L6pine and his pupils, which Beemed 

 to show thai diabetic blood did nol possess the glycolytic power of 

 normal blood; and those of Cohnheim, from which it was concluded that 

 mixtures of the expressed juices of muscle (liver) and pancreas, although 

 ordinarily destroying glucose, failed to do so when they were taken from 

 a diabetic animal, are now known to be erroneous. 



The failure to show a depression of glycolytic power by these methods 

 prompted Knowlton and Starling 24 to investigate the question whether 

 any difference is evident in the rate with which glucose disappears Prom 



a mixture <>f hi 1 and saline solution used to perfuse a heaii outside 



the body, according to whether the hear! was from a normal or a dia- 

 betic dog. In the first series of observations which these workers made. 



it was thoughl that the normal heart used glucose at the pate of ahout 

 i m<_ r . pei' gram of heart substance per hour: whereas that <<\ a dia- 

 betic (depancreatized) animal used less than 1 mg. If such Btriking 

 differences in the rate of sugar consumption could make themselves 



manifest \\>v SO relatively small a mass of muscular tissue as that of the 



heart, it is permissible to assume that a much more striking din* 

 could he demonstrated when the perfusion fluid is made to traverse all 

 oi- practically all of the skeletal muscles, as well ;is the heart. For this 

 purpose an eviscerated animal max- he employed that is, one in which 

 the abdominal viscera are removed after ligation of the celiac axis and 

 mesenteric arteries, and the liver is eliminated by mass ligation of its 

 lobes. rsim_ r such preparations, R »> Pearce and Macleod ' found that 



the rate at which glucose disappears from the blood, although \ 



irregular, is in no way differenl in completely diabetic 



with normal ihejs. They were thus unable to confirm any of Knowlton 



and Starling's earlier conclusions. Patterson and Starling subsequently 



pointed out that a serious error was involved in the earlier perfus 

 experiments, partly on accounl of a remarkable but irregular dis 

 pearance ^( glucose from the lungs, and partly because the diabetic 



heart may contain a considerable <\ f glycogen, from which its 



