388 FAT METABOLISM. OBESITY 



reverse takes place when oil-bearing seeds come to sprout, 20 

 the oil being converted in greater part into carbohydate, 

 going directly as it disappears from the reserve stock into the 

 formation of material from which the cell walls of the young 

 plants are constructed. Many bulbs and, too, ever-green 

 leaves, and even wood, may contain reserve fats. In many 

 trees starch disappears from the wood in winter, consider- 

 able amounts of fat taking its place ; in the spring there is a 

 return of the fat into carbohydrate, and the process may 

 be to a certain degree reversed by artificial chilling. 



Characteristics of Fat which is Formed de novo from 

 Carbohydrates. The fat formed de novo in the animal body 

 from carbohydrate is characterized by its low proportion of 

 oleic acid and its peculiar firmness. Gr. Eosenfeld found 

 that nine-tenths of the fat of fasting geese consisted of oil, 

 with only a trace of solid fat in it; the fat of geese which 

 had been fed freely on potatoes was, however, of a distinctly 

 firmer consistence (very like lard), which did not become 

 soft at full summer heat and when tried out consisted for 

 the most part of crystals of palmitic acid and stearic acid 

 glyce rides, with which only a small amount of fluid fat was 

 mixed. In mirror carp, too, which were freely fed on seeds 

 in a bowl, the engorgement with carbohydrate led to a fat 

 poor in oleic acid. 21 If the same conditions obtain in man, 

 there ought to be a distinct difference observable between 

 the adipose layer of Esquimaux, who assimilate the fluid 

 fat of the north polar animals, and that of a negro or China- 

 man in whom free rice diet has helped to produce a well 

 developed panniculus adiposus; and this may well have 

 some physiological significance. For instance, it may be 

 readily thought that an individual with fat containing con- 

 siderable oleic acid would be in position to more rapidly 

 mobilize his fat supply than one in whom the firm fats pre- 

 vail. Perhaps there is some difference whether a child as- 



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

 21 G. Rosenfeld, Ergebn. d. Physiol., 1', 670, 1902. 



