258 HALOIDS AND HALOID BASES. 



singault's experiments,, to be too rapidly absorbed from the 

 intestinal canal to allow of their being subjected to a fatty 

 fermentation. 



Liebig has advanced an hypothesis, that fat may also be formed 

 from nitrogenous elements of food; and this view would appear to 

 acquire support from the experiments made by Boussingault on 

 ducks. For the latter observer found that when these birds had 

 been fed on albumen and casein, containing little or no fat, there 

 was always more fat in their intestinal contents than when they 

 had fasted for any length of time, or been fed only on clay, starch, 

 or sugar. Unless, therefore, we would assume (which, indeed, we 

 have no authority for doing,) that fat is secreted in the intestinal 

 canal after the use of nitrogenous substances, we must admit, from 

 the above experiments, that a portion of fat may be generated in 

 the primce via from albumen containing no fat. It must, however, 

 be observed, on the one hand, that the increase of the fat in the 

 intestinal canal, after the use of albuminous food, is very incon- 

 siderable, and on the other, that the experiments are so few in 

 number, that we have not sufficient data for the satisfactory solu- 

 tion of so important a question. But it is very possible that the 

 digestion of nitrogenous food may be accompanied by a greater 

 secretion of bile than that of non-nitrogenous substances, and that 

 the fats and products of decomposition of the bile, may have 

 increased the ether-extract of the contents of the intestine, in the 

 above experiments, after the use of nitrogenous food. As has 

 been already observed, the solid excrements presented scarcely 

 any residua of the bile except those which are soluble in ether. 



Since the above facts do not, as yet, justify us in assuming that 

 the seat of the formation of fat must be sought in the prima via, 

 we must turn to the processes at work in the blood, unless, indeed, 

 we freely confess that nothing definite can, at present, be advanced 

 on this subject. 



The third question, as to how fat is formed from other sub- 

 stances, would next engage our attention, if the preceding consider- 

 ations did not show that we are entirely deficient in the materials 

 necessary for affording a satisfactory answer. For, so long as we 

 are ignorant of the grounds on which a process is based, although 

 we may be acquainted with its individual factors, we must 

 defer all idea of a scientific explanation ; there is, however, no 

 deficiency of imaginary schemes to explain the formation of fat 

 from sugar or protein. Support has been borrowed from the 

 somewhat irrelevant fact of the butyric fermentation of sugar 



