THE METABOLISM OF THE CARBOHYDRATES 



699 



TWENTY GKAMS OF THE VARIOUS AMINO BODIES WERE GIVEN TO 

 PHLORHIZIN-DIABETIC DOGS 



Glutamic acid 

 COOH 



13.31 



CH 2 



CH a CHNH 2 

 COOH 



to glucose 



Three of the five 

 C atoms converted 

 to glucose 



12.24 



that the total yield of glucose from them could be 26.3 grams; thus 

 accounting for nearly one half of the 66 grams which a diabetic animal 

 produces from 100 grams of flesh. 



Gluconeogenesis in Normal Animals. Although it has been clearly 

 shown by the indirect method that not only protein but its decomposi- 

 tion products as well, can be readily converted into glucose, yet this does 

 not necessarily indicate that a similar conversion occurs in the nondia- 

 betic animal. That such is the case, however, can be shown in various 

 ways. Thus, at the end of a period of long starvation considerable 

 quantities of glycogen are quite commonly found in the body, and the 

 blood sugar, although lower than normal, never entirely disappears. 

 Now, since no carbohydrate is being ingested, and the body stores of this 

 foodstuff become exhausted early during starvation (cf. page 695), it 

 is evident that the carbohydrate must be produced from the protein of 

 the animal's body. A still more convincing experiment can be con- 

 ducted by producing strychnine convulsions in a starving animal. If 

 the animal is killed after the convulsions have lasted for a certain time, 

 the tissues will be found almost if not entirely free of glycogen, 

 but if the convulsions are made to disappear by giving chloral and the 

 animal allowed to sleep for some time before killing it, glycogen again 

 accumulates in the body. This glycogen must have been manufactured 

 out of noncarbohydrate material. 



Corroborative evidence of a somewhat different nature is furnished by 

 an examination of the respiratory quotient, which, it will be remem- 

 bered (page 582), varies according to the nature of the foodstuff or body 



