[ 439 ] 



LXI. On the Sources of the Fat of the Animal Body, By J. B. 

 Lawes, F.R.S., F.C.S., and J. H. Gilbert, Ph.D., F.R.S., 



F.C.S.* 



N 1842, Baron Liebigf maintained that the fat of Herbivora 

 must be derived in great part from the carbo-hydrates of their 

 food, but considered that it might also be produced from nitro- 

 genous compounds. MM. Dumas and Boussingault J at first 

 called in question this view ; but subsequently the experiments 

 of Dumas and Milne-Edwards § with bees, of Persoz || with geese, 

 of Boussingault \ with pigs and ducks, and of ourselves with 

 pigs**, w^ere held to be quite confirmatory of Liebig's view, at 

 any rate so far as the formation of fat in the animal body from 

 carbo-hydrates was concerned. 



In 1864, however, at the Bath Meeting of the British Asso- 

 ciation for the Advancement of Science, Dr. Hayden, of Dublin, 

 read a paper before the Physiological Section, in which, basing 

 his conclusions upon certain physiological considerations of a 

 purely qualitative kind, he argued that fat was not producible 

 in the body from sugar and allied substances, but that both 

 eventually served for the production of carbonic acid and water ; 

 and sugar being the most readily oxidized, so saved the com- 

 bustion, and favoured the storing of fat. 



Again, in August 1865, at a Meeting of the Congress of 

 Agricultural Chemists, held in Munich (at which one of the 

 authors was present), Professor Voitff, from the results of ex- 

 periments with dogs fed on flesh, maintained that fat must have 

 been produced from the nitrogenous constituents of the food, 

 and that these were probably the chief if not the only source of 

 the fat, even of Herbivora. In favour of the probability of this 

 view, Professor Voit refers to the formation of adipocere from 

 nitrogenous substance; but he mainly relies upon the fact that, 

 in experiments by Pettenkofer and himself in which large quan- 

 tities of flesh were given to a dog, the whole of the nitrogen re- 

 appeared in the form of urea and in the faeces, whilst only a 

 portion of the carbon was recovered in the urine, fseces, and the 

 products of respiration and perspiration, from which it was con- 

 cluded that some had been retained in the body, and had con- 



* Communicated by the Authors. 



t Organic Chemistry of Physiology and Pathology, p. 81 et seq. 



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



§ Comptes Hendus de VAcademie des Sciences, vol. xvii. p. 731. 



|| Ann. de CMm. et de Phys. vol. xiv. p. 408 et seq. 



ifi Ann. de CMm. et de Phys. vol. xiv. p. 419 et seq. ; xviii. p. 444 et seq. 



** " On the Composition of Foods in relation to Respiration and the 

 Feeding of Animals," Report of the British Association for the Advance- 

 ment of Science for 1852. 



tf Versuchs-Stationen Organ, vol. viii. No. 1, 1866, p. 23. 



