FATS. 257 



attribute to fat, namely, whether we derive it from albuminous, 

 and therefore nitrogenous substances, or from starch, sugar, and 

 other non-nitrogenous matters. Liebig's authority has given 

 currency to the latter view, although it is opposed by many physio- 

 logical facts. For if fat were formed in the primes vice from the 

 starch of vegetables, the chyle would contain more fat after a 

 vegetable than a fatty animal diet ; but the contrary has invariably 

 been noticed in all the observations made on this subject since the 

 experiments of Tiedemann and Gmelin. Boussingault* moreover did 

 not observe any instance in his recent experiments on ducks, in 

 which the fat contained in the intestinal contents, was increased 

 by feeding the birds on starch or sugar, although such must have 

 been the case if a metamorphosis of these substances into fat 

 occurred in this part of the system. Thomsonf was also led by 

 his experiments on the influence of different kinds of food on 

 the production of milk and sugar, to adopt the opinion that sugar 

 had no part in the formation of fat. The occurrence of hydroge- 

 nous gases in the intestines, and the well-known fact of the 

 reduction of alkaline sulphates into sulphides during the process 

 of digestion in the intestinal canal, might indeed seem to afford 

 some grounds for the possible reduction of the substances con- 

 taining carbon and the elements of water, to which we apply the 

 term carbo-hydrates, viz., starch, sugar, &c. ; but until supported 

 by some conclusive evidence, this view must be regarded as 

 scarcely tenable in opposition to the facts referred to. H. MeckelJ 

 was indeed led to believe, from some experiments made on the 

 subject, that sugar was thrown into a sort of fermentation by the 

 bile, and was thus converted into fat ; but it had escaped the 

 attention of Meckel, who regarded every substance that dissolved 

 in ether as a fat, that his etherial extract contained not only fat, 

 but all the products of decomposed bile soluble in ether; and the 

 reason of his obtaining a larger quantity of ether-extract when the 

 bile was decomposed by sugar, than when digested without sugar, 

 was simply in consequence of the presence of the sugar, which very 

 much promotes the decomposition of the bile, and the formation 

 of products easily soluble in ether (namely free biliary acids.) 

 It does not, therefore, appear from the facts already established, 

 that fat is generated in the intestinal canal from sugar and starch, 

 more especially as these substances would appear from Bous- 



* Compt. rend. T. 20, p. 1726. 



t Ann. d. Ch. u. Pharm. Bd. 61, S. 228-243. 



t De genesi adipis in animalibus. Diss. inaug. Hal. 1845 C 



