246 FORMATION OF SUGAR FROM FAT 



doubtless there may be much said for it) that the body can 

 execute its manifestations of energy (in a certain sense, 

 render its cash payments) only on a carbohydrate stand- 

 ard, the assumption of sugar formation from fat is still 

 asserted even if not in so many words ; for it can scarcely 

 be questioned that in the starving animal the performance 

 of work must draw upon its supplies of fat, or that a human 

 being in a long continued fever, or a hibernating marmot, 

 undoubtedly sustains the output of energy for the most part 

 at expense of its body fat. If in such examples the direct 

 source of mechanical and thermic energy were to be refer- 

 able to the combustion of sugar alone, the conclusion must 

 be that a great part of this sugar must come from fat. The 

 problem of sugar formation from fat therefore falls in a 

 certain sense in the same class with that of the sources of 

 energy of the living body, and any one who adheres to 

 Zuntz's belief (v. Vol. I of this series, p. 159, Chemistry of 

 the Tissues) in the dynamic equivalence of the three main 

 classes of foods, will necessarily refuse to acquiesce in the 

 last mentioned argument. 



There is no doubt that in the plant in the germination of 

 its oily seed (where the reserve substances in the cotyledons 

 and in the endosperm furnish the material for the growth of 

 the embryonal plant) there takes place a transformation of 

 fat into carbohydrate to a very great degree. The fat that 

 is disappearing from the reservoirs of reserve substance 

 actually forms the material from which the cell-walls of the 

 young plants are built up. But it is perhaps not apposite to 

 apply facts which have been discovered in plant physiology 

 to animal metabolism. 67 



67 Literature upon the Behavior of the Fat in Germination of Oil-bearing 

 Seeds : O. v. Fiirth, Hofmeister's Beitr., 4, 430, 1903. 



