TRANSFORMATION OF FAT INTO CARBOHYDRATE 387 



absolute proof was attained by forced feeding of varions 

 experiment animals, like pigs, sheep, dogs, and geese, on fat- 

 free food, poor in protein but rich in carbohydrates, after a 

 previous fasting. Careful equilibrium experiments showed 

 that large amounts of carbon are retained in the body. That 

 this was not retained in the form of protein carbon was 

 proved by calculating the retained nitrogen. Even granting 

 that a high proportion of glycogen could be accepted as 

 accumulated by the process, there still remained a large over- 

 plus of carbon which could not be accounted for save as 

 representing new-formed fat. 



The conversion of carbohydrate into fat is shown in 

 respiration experiments by a marked rise of the respiratory 

 quotient. Sugar being rich in oxygen and fat poor in oxygen, 

 transformation of the former into the latter will set free 

 considerable oxygen which may be used to burn carbon into 

 carbonic acid. This will lead to an increase in the numerator 

 of the ratio between the exhaled carbonic acid and the inhaled 



p*o 



oxygen, 2 the amount of C0 2 eliminated increases with- 

 out increase of the oxygen inhaled. Thus Bleibtreu noted, in 

 case of geese stuffed with carbohydrates, and Pembrey in 

 marmots, which were preparing for hibernation and taking 

 on a large supply of fat by gorging with carbohydrates, in 

 order to enable themselves to pass the winter a respiratory 

 coefficient which reached nearly 1.4. This amounts to almost 

 double the proportion to be met in a normally fed individual. 

 Transformation of Fat into Carbohydrate in the Vege- 

 table Economy. For the most part in these lectures it is 

 unfortunately impossible to bring forward the analogies 

 which exist between the metabolism of animals and plants. 

 In the present connection, however, attention should be called 

 to the fact that the plant economy is likewise able to change 

 carbohydrate into fat and vice versa. While, for example, 

 unripe oily seeds contain much starch and mannite, as they 

 ripen the carbohydrate is converted into oil. However, the 



