ARE FATS FORMED FROM PROTEIDS OF FOOD 1 933 



fatty series are formed. And although it is not easy at first sight to 

 understand, from a chemical point of view, how carbohydrate molecules are 

 transformed into fatty molecules, we are not obliged to assume direct trans- 

 formation, for it may well be that the carbohydrates are broken down into 

 comparatively simple compounds, and that these are built up again by the 

 organism into fat. 



The observations of Hanriot, with Richet, 1 furnish indirect evidence of the 

 transformation of carbohydrate into fat. These observers found that, with the 

 administration of carbohydrate food, there is a greatly increased output of 

 carbon dioxide without a corresponding increase of oxygen intake. This fact 

 may be explained, according to Hanriot, by a transformation of carbohydrate 

 into fat, 2 in conformity with such an equation as the following : 



13(0^,0,) = C 55 H 104 6 + 23(C0 2 ) + 26(H 2 0) 



(oleo-stearo- 

 palmitin) 



Are fats formed from the proteids of the food ? This is a question 

 which was for many years held to have been settled by the experiments 

 of Pettenkofer and Voit, and subsequently of Voit. 3 These observers 

 found that if a dog is kept in a respiration chamber, and fed entirely on 

 lean meat, all the ingesta and egesta of the body being carefully deter- 

 mined and analysed, a comparison of the results shows clearly that in 

 many cases carbon of the proteid is retained within the body, and is 

 presumably in the form of fat, the amount of fat and carbohydrate in 

 the food being altogether too small to suppose that the carbon laid by 

 could have been derived from anything but the proteids of the food. 

 Moreover, proteid food increases the amount of fat in the milk of 

 suckling animals, and a bitch fed upon lean meat may produce much 

 more fat in her milk than can be accounted for by the fat and carbo- 

 hydrates of the food produces, indeed, milk especially rich in fat, when 

 fed exclusively on lean meat. 4 



In confirmation of observations of this kind have been adduced the 

 statements that the milk of suckling animals and of nursing women 

 is richer in cream in proportion to the amount of proteid taken in the 

 diet ; that fat becomes formed in large amount by the larvae of blow- 

 flies, which are fed upon defibrinated blood, containing only very small 

 quantities of non-proteid organic material ; 5 that in the ripening of 

 cheese there is a diminishing amount of proteid, and an increasing 

 amount of fat ; 6 and that in the formation of adipocere from flesh, there 

 is found a diminished amount of. proteids, and an increased amount of 

 fatty acids. 7 The formation of fat in the liver and tissues of a starving 



1 Compt. rend. Acad. d. sc., Paris, 1892, tome cxiv. p. 371. 



2 Cf. also Gautier, ibid. , p. 374. 



3 Ann. d. Chem. u. Pharm., 1862, Suppl. Bd. S. 52 and 361; Ztschr. f. Biol, 

 Miinchen, 1869, Bd. v. ; also 1870 and 1871, Bde. vi. and vii. ; art. " Ernahrung, " in 

 Hermann's "Handbuch," Bd. vi. S. 249. 



4 Ssubotin, Virchow's Archiv, 1886, Bd. xxxv. S. 561 ; and Centralbl.f. d. med. Wiss- 

 ensch., Berlin, 1866, S. 337; Kemmerich, ibid., S. 467. Both Ssubotin and Kemmerich 

 worked with Pfliiger. See also Voit, Ztschr. f. BioL, Miinchen, 1869, Bd. v. S. 137. 



5 Fr. Hofmann, Ztschr. f. BioL, Miinchen, 1872, Bd. viii. S. 159. 



6 See on the changes accompanying the ripening of cheese, Sieber, Journ. f. prakt. 

 &hem., Leipzig, 1880, N. F., Bd. xxi. S. 203 : Jacobsthal, Arch. f. d. ges. PhysioL, Bonn, 

 1893, Bd. liv. S. 484. 



7 Lehmann (Sitzunysb. d. phys.-mcd. Gesellsch. zu Wiirzburg, 1885, S. 19) obtained an 

 increase of fatty acids to the extent of 3*7 per cent, in meat kept in running water for some 

 months. E. Voit (Miinchen. med. Wclmschr., 1888, S. 518) got an increase of 2 per cent, 

 when it was kept in milk of lime, thus excluding fungi. 



