714 METABOLISM 



carbohydrate." This conclusion, however, awaits confirmation by more 

 direct methods. 



In spite of the failure to show that the isolated tissues of diabetic 

 animals have a lower glucose-consuming power than those of normal 

 animals, it is important from a practical standpoint that we should 

 know something regarding the possible nature of the disturbance which 

 a removal of the pancreas entails. Even if we could not tell exactly 

 how this disturbance operates, it would be of value to know whether 

 it depends on the removal from the organism of some hormone that is 

 essential to carbohydrate utilization, for, if this were proved to be the 

 case, encouragement would be offered to seek for the chemical nature 

 of this hormone so that we might administer it with the object of re- 

 moving the diabetic state. The hope of a fruitful outcome of such an 

 investigation is encouraged by the success of researches on diseases of 

 other ductless glands, particularly the thyroid. 



The removal of some hormone necessary for proper sugar metab- 

 olism is, however, by no means the only way by which the results can 

 be explained, for we can assume that the pancreas owes its influence 

 over sugar metabolism to some change occurring in the composition of 

 the blood as this circulates through the gland a change which is de- 

 pendent on the integrity of the gland and not on any one enzyme or 

 hormone which it produces. It is obvious that the results of removal 

 of the gland could be explained in terms of either view, and indeed 

 there is but one experiment which would permit us to decide which of 

 them is correct. This consists in seeing whether the symptoms which 

 follow pancreatectomy are removed, and a normal condition reestab- 

 lished, when means are taken to supply the supposed missing internal 

 secretion to the organism; if they should be, conclusive evidence would 

 be furnished that it is by "internal secretion" and not by "local in- 

 fluence" that the gland functionates. 



The experiments have been of two types: in the one, variously pre- 

 pared extracts of the glands have been employed, and in the other, 

 blood which is presumably rich in the internal secretion. The most 

 recent work has shown that injection of pancreatic extracts into a de- 

 pancreatized animal produces no change in the respiratory quotient, 

 although injections of extracts of pancreas and duodenum may cause 

 a temporary fall in the excretion of glucose in the urine on account of the 

 alkalinity of the extract. Neither have experiments with blood transfusions 

 yielded results that are any more satisfactory. In undertaking these ex- 

 periments it is of course assumed that the internal secretion is present in 

 the blood, and that if this blood is supplied to an animal suffering from pan- 

 creatic diabetes carbohydrate metabolism will become normal. The general 



