CHEMICAL COMPONENTS OF THE HUMAN BODY. 



cated, though never in perfect health nor its detection in the urine or in va- 

 rious fluids exuded from the blood, affords the least evidence that it was pre- 

 formed there ; any more, indeed, than does the accumulation of the coloring 

 matter which makes its presence so obvious in jaundice. Of that evidence 

 which is furnished in the case of the urine, by the detection of some of its cha- 

 racteristic components in the tissues which undergo most rapid disintegration, 

 we have here a most complete deficiency ; for no trace of the biliary acids has 

 yet been found in the tissues, except under circumstances which justify the 

 belief that these substances were deposited there. The only distinct indication 

 yet obtained, that the characteristic components of bile are preformed in the 

 blood (Cholesterine being scarcely to be reckoned as such), is afforded by the 

 experiments of Kunde, one of the pupils of Lehmann ; who demonstrated, by 

 Pettenkofer's test, the presence of biliary matters in the blood of frogs whose 

 livers had been extirpated. On the other hand, there is much that indicates, if 

 it does not prove, that the function of the liver is not the mere selection and 

 elimination of the elements of bile from the blood ; but that it exercises a most 

 important transforming power, both over the constituents of the blood, and 

 over those of the bile. Of the evidence which has been lately adduced in proof 

 of the first of these positions, some notice has already been taken ( 40, 46) ; 

 and that of the second will be more appropriately considered hereafter (CHAP. 

 xn. SECT. 2). At present it will be sufficient to remark, that, whilst a chemi- 

 cal comparison of the elements of the Bile and Urine shows that each of these 

 excretions is (so to speak) the complement of the other, and that the mass of 

 the blood or of the solid tissues might resolve itself into these two sets of com- 

 pounds ( 91), various physiological and pathological phenomena seem to indi- 

 cate, that the products of the metamorphosis of the tissues which afterwards 

 become the components of bile, do not take the form of those components until 

 they have been acted on by the liver, and reduced to a state comparatively innox- 

 ious. For whilst there is abundant evidence that the constituents of bile, both its 

 resinous acids, and its coloring matter, may be reabsorbed without serious injury; 

 and whilst there is strong reason to believe that, as regards the resinous acids, such 

 reabsorption is habitual; there is adequate proof, on the other hand, that the reten- 

 tion within the circulating current of the matters from which bile is formed, owing 

 to structural disease or functional inactivity of the liver, is attended with the most 

 serious consequences, and will, if prolonged, induce a fatal result. It is surmised 

 by Lehmann, in consequence of the resemblance already pointed out between the 

 cholic and oleic acids, that bile is partly formed from the fatty matters of the 

 system ; but there is no adequate proof of this ; and as we have seen that fatty 

 matters may themselves be formed by the metamorphosis of albuminous sub- 

 stances ( 40), there seems no reason to dissent from the usually received opin- 

 ion, that the chief source of biliary matter is ultimately to be found in the dis- 

 integration of the azotized tissues. 



6. Inorganic Substances forming part of the Living Body, and contained in its 



Excretions. 



72. Although it might have been supposed that the Chemist would have had 

 comparatively little difficulty in determining what are to be regarded as the In- 

 organic or Mineral constituents of the body, yet the attainment of a precise 

 knowledge of them is attended with peculiar difficulties, arising out of the mode 

 in which these constituents are blended with Organic compounds. The usual 

 method of determining their presence, nature, and amount, has been to incine- 

 rate the dried tissue or the solid residue of the fluid, and to analyze the ash 

 which remains ; but this process, as Prof. Lehmann justly remarks, gives us no 

 information with regard to the combinations in which the constituents of that 



