TRANSACTIONS OF THE SECTIONS. 41 



On the Sources of tlie Fat of the Animal Body. Bi/ J. B. Laaves, F.B.S., 

 F.G.S., and J/H. Gilbekt, Ph.D., F.B'.S., F.C.S.* 



In 1842, Baron Liebig liad concluded that the fat of Herbivora must be derived 

 in great part from the carbo-hydrates of their food, but that it might also be pro- 

 duced from nitrogenous compounds. MM. Dumas and Boussiugault at first called 

 in question this view; but subsequentl}' the experiments of Dumas and Milne- 

 Edwards with bees, of Persoz with geese, of Boussingault with pigs and ducks, and 

 of the authors with pigs, had been held to be quite coniirmatory of Liebig's view ; 

 at any rate so far as the formation of fat from the carbo-hydrates was concerned. 

 In 1864, however, at the Bath Meeting of the British Association, Dr. Ilayden, of 

 Dublin, read a paper before the Physiological Section, in which, basing his conclu- 

 sions upon certain physiological considerations .of a purely qualitative kind, he ex- 

 pressed doubt on the point. In August 1865, again, at a meeting of the Congress of 

 Aoricultural Chemists, held at Mimich, Professor Voit, from the results of experi- 

 ments with dogs fed on llesh, maintained that fat must have been produced from 

 the nitrogenous constituents of the food, and that these were probably the chief, if 

 not the onlv source, of the fat even of Herbivora. In the course of the discussion 

 which followed. Baron Liebig disputed this conclusion ; and his son, Hermann von 

 Liebig, has since written a paper on the subject, in which, illustrating his views by 

 reference to experiments with cows, he admits the probability that fat may be 

 formed from nitrogenous substance, but nevertheless concludes that this is neither 

 the onlv nor even the chief source of fat, in the ordinary feeding of Herbivora. 



The authors agi-eed with the conclusions of these latter authorities. The data 

 cited by Hermann von Liebig did not, however, afford conclusive evidence on the 

 point ; and they considered that the results of experiments with cows were, in 

 several respects, less appropriate for the purposes of tho inquiry than those with some 

 other animals. They showed, illustrating the various points by reference to expe- 

 riments of their own, that, compared with either cows, oxen, or sheep, the pig had 

 a much less proportion of alimentary organs and contents, consumed food of a much 

 hio'her character, produced a much larger amount of fat both in relation to a given 

 weight of animal within a given time and to the amount of food consumed, voided 

 a much less proportion of tlae solid matter of its food in its solid and liquid excre- 

 tions, and, finally, its increase contained a larger proportion of fat. For these rea- 

 sons results obtained with pigs must be much more conclusive as to the sources in 

 the food of the fat which they yield than those with either cows, oxen, or sheep. 



Tables were exhibited shomng the results which had been obtained by the authors 

 in numerous experiments with pigs ; and from these the following main conclusions 

 were drawn : — 



1. That certainly a large proportion of the fat of the Herbivora fattened for human 

 food must be derived from other substances than fatty matter in the food. 



2. That when fattening animals are fed upon their most appropriate food, much 

 of their stored-up fat must be produced from the carbo-hydrates it supplies. 



■3. That nitrogenous substance may also serve as a source of fat, more especially 

 when it is in excess, and the supply of available non-nitrogenous constituents is 

 relatively defective. 



On the Poisonous Nature of Crude Paraffin OU, and the Products of its Becti- 

 fication itj)on Fish. By Steat;nsox Macadam, Ph.D., F.B.S.K, F.C.S., 

 Lecturer on Chemistry, Surgeons' Hall, Edinburgh. 



The gi'eat extension of paraifin oil-works, both crude and refined, during the last 

 few years, has led to attention being directed to the nature of the discharges which 

 emanate from such, more especially to those matters which find their way into 

 rivers which form the natm-al drainage of the district. The deleterious nature of 

 these dischai'ges has manifested itself already in the total destruction of all fish in 

 more than one of oiu' Scottish streams, and to the impregnation of the water with 

 paraffin oil, and the products of its rectification, to such an extent as to impart the 

 characteristic taste and odour of paraffin to the water, and render it unsuitable for 

 domestic purposes. 



* For fi.dler report, see the Philosophical Magazine for December 1866. 



