710 METABOLISM 



greater or a less expulsion of carbon dioxide from it. Thus, if acids 

 appear in the blood, they will dislodge carbon dioxide, and apparently 

 cause the respiratory quotient to rise. Alkalies, on the other hand, ap- 

 parently cause the quotient temporarily to fall, and unless the observa- 

 tions are done over a long period of time and with great care, faulty 

 conclusions are very apt to be drawn from the results. Starling and 

 Evans 65 have measured the respiratory exchange in the heart lung prep- 

 aration (see page 163) and have found that the heart uses an average of 

 3.2 c.c. of oxygen per gram an hour when doing moderate work, the 

 E.Q. being 0.85. This corresponds to 1.6 mg. glucose consumption per 

 gram per hour, thus corroborating the results obtained by direct estima- 

 tion of glucose. 



Diabetes and the Ductless Glands 



We are now in a position to consider the forms of experimental dia 

 betes produced by disturbances in the ductless glands. 



Relationship of the Pancreas to Sugar Metabolism. In no other of 

 the many causes of diabetes has greater interest been shown than in 

 that due to disturbance in the pancreatic function. Many of the earlier 

 clinicians who followed cases of diabetes mellitus into the postmortem 

 room, noted that definite morbid changes in the pancreas were a fre- 

 quent accompaniment of the disease. Prompted by these observations, 

 several investigators attempted experimental extirpation of the gland, 

 but did not succeed in producing glycosuria in the few animals that 

 survived the operation. Their failure, no doubt, was due to incom- 

 plete extirpation. To reduce the severity of the operation, Claude Ber- 

 nard injected oil into the pancreatic duct, and tied it; but he succeeded 

 in keeping only two dogs alive for any length of time, and these did 

 not exhibit glycosuria. Neither were other investigators that adopted 

 similar methods any more successful. It looked as if the pancreas had 

 no relationship to carbohydrate metabolism. In the year 1889 Minkowski 

 and von Mering in Germany, and de Dominicis in Italy, by thorough 

 extirpation of the gland, succeeded in producing in dogs a marked and 

 persistent glycosuria, accompanied by many of the other symptoms of 

 diabetes. The first two authors attributed the condition to removal of 

 an internal secretion. 



The course of the diabetes produced by complete pancreatectonry is, 

 however, somewhat different from that usually observed in man. It is 

 extremely acute from the start, the G:N ratio being 3.6:1 (see page 

 696), and it is unaccompanied by any of the classical symptoms seen in 

 the clinical condition. Experimental pancreatic diabetes can, however, 

 be made to simulate very closely the disease in man. This was first of 



