Manual of physiology / By William Senhouse Kirkes, assisted by James Paget.

  • William Senhouse Kirkes
Date:
1849
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Licence: Public Domain Mark

Credit: Manual of physiology / By William Senhouse Kirkes, assisted by James Paget. Source: Wellcome Collection.

    26/574 (page 18)
    i. « ia CHEMICAL COMPOSITION OF _ of the original compound finally unite to form those substances - whose composition is, under the circumstances, most stable.* It is not known how far the process of decomposition which thus occurs in dead animal matter is imitated in the living body ; but the facility of decomposition which it indicates may be con- stantly effected during life tranquilly, and without the intervention of any such comparatively violent forces as are used in chemical] — art. The instability which organic compounds show when dead makes them amenable to the chemical forces exercised on them during life by the living tissues—forces inimitably gentle, so slight that their operation is not discernible by any effects besides those which they produce in the living body. What has been said respecting the mode in which the ele- ments are combined in the composition of animal matter refers only to the four essential elements. Little or nothing is known of the mode in which the incidental elements, or their compounds, are combined with the compounds formed of the essential ele- ments; only it is probable that they are combined chemically, and as necessary parts of the substances they contribute to form. Of the natural organic compounds existing in the human body, some occur almost exclusively in particular tissues or fluids; as the colouring matter of the blood and other fluids, the fatty matter of the nervous organs, &c. But many exist in several different parts, and may, therefore, be now described in general terms. They may be arranged in two classes, namely, the azotized or nitrogenous, and the non-azotized or non-nitrogenous principles. The non-azotized principles include the several fatty, oily, or oleaginous substances, of which, in the human body, the most abundant are named margarine, elaine or oleine, stearine, chole- stearine, and cerebrine. The fatty substances are, nearly all, compounds of carbon, hy- drogen, and oxygen. ‘They burn with a bright flame, the pro- portion of oxygen being less than would be sufficient to form * An interesting account of the nature of the so-called spontaneous decom- .position of dead organic matter is given by Dr. Helmholtz (Ixxx. 1843) : for an abstract of the paper see xxv. 1843-4, p.5, The experiments of Helm- holtz show, that although the results of spontaneous decomposition are RE fied by the presence of infusorial organisms, yet these are not, as has been supposed, essential to the occurrence of the process: their existence in large quantities in decomposing animal matters is due to the fact, that such de- composition furnishes the most favourable conditions to their development and life. Consult, also, on this subject, Liebig, in the last edition of his Animal Chemistry.