284 the eothamsted experiments. 



Sources in the Food of the Fat produced in the 

 Animal Body. 



Source Prior to the publication of Liebig's work on Organic Chem- 



offat. istry in its Applications to Physiology and Pathology, in 1842, 

 it seems to have been assumed that the Herbivora derived 

 their fat from ready-formed fatty matters in their food ; and 

 that the Carnivora derived theirs from the ready-formed fat 

 Liebig's of the animals they consumed. Liebig argued that, as a rule, 

 the food consumed by the Herbivora did not contain suffi- 

 cient fatty matter for the purpose ; and he maintained that, 

 although fat might be formed from the nitrogenous substance 

 of the food, its main source was the starch, sugar, and other 

 carbohydrates, which the food supplied. 

 Opinion Dumas and Boussingault x at first called in question the 



auUand' yiQW that fat was produced in the animal body, and assumed 

 others. that the food of the Herbivora supplied sufficient fatty matter 

 to account for the whole of the fat stored up. Subsequently, 

 however, Dumas and Milne-Edwards, 2 from the results of ex- 

 periments with bees, Persoz 3 from experiments with geese, 

 and Boussingault 4 from those with pigs, geese, and ducks, 

 concluded that fat was formed from the carbohydrates of the 

 food. At the same time Boussingault considered that, in 

 normal feeding, the amount of albuminoids consumed would 

 generally supply sufficient carbon for the production of the 

 fat formed by the animal. 

 Rotham- Next came the evidence of the Eothamsted experiments, 



sted expert- ftiQ majority of which were conducted within the years 1848- 

 1853 inclusive; and they involved feeding experiments on 

 between 400 and 500 animals, with foods of known composi- 

 tion ; the slaughter, determination of the weights of the parts, 

 and noting on the character as to fatness, &c, of more than 

 300 animals ; and finally, the chemical analysis of ten animals. 

 Fat in ani- In the first place, it was clearly demonstrated that much 

 mats and more f a t was stored up in the bodies of the fattening animals 

 than could be derived from the ready-formed fatty matter in 

 their food. Secondly, from a careful study of the enormous 

 amount of experimental data obtained, as well as of the 

 known facts of practical experience in feeding, it was con- 

 sidered no doubt whatever could be entertained that much, 

 Fat derived if not the whole, of the fat formed in the bodies of the 

 fr°f c ^ bo ' herbivora fed for the production of meat was derived from 

 the carbohydrates of the food. 



1 Balance of Organic Nature, 1844, p. 116 et seq. 

 3 Compt. Rend., vol. xvii. p. 531. 



3 Ann. Chim. Phys., vol. xiv. p. 408 et seq. 



4 Ibid., vol. xiv. p. 419 et seq.; xviii. p. 444 et seq. 



