On the proportion of nitrogen contained in alimentary substances taken from both the organic kingdoms as a comparative measure of their nutritive power.

  • Schlossberger, J., Dr.
Date:
[1845]
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Licence: Public Domain Mark

Credit: On the proportion of nitrogen contained in alimentary substances taken from both the organic kingdoms as a comparative measure of their nutritive power. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    LIII. On the PropoTtion of Nitroge7i contained, in Alimentary Substances taken from both the Organic Kingdoms as a com- parative measure of their Nutritive Power. By Dr. J. ScHLossBERGER and Alexander Kemp, Assistant Chemi- cal Teachers in the University of Edinburgh^. ^HE distinction between the elements of the reproductive and those of the respiratory functions, is probably one of the most fertile ideas for which physiology is indebted to modern chemistry; even if we do not admit that division in its full extent, nevertheless we must allow it to be a beautifully conceived idea, and one founded on a great amount of observa- tion. It may be assumed with safety that no other classifica- tion of the substances comprised under the vague designation of alimentary bodies, has in an equal degree represented the essential differences in their chemical composition and their physiological effects, or has presented to the eye of the mind the important part which these substances perform, as the above-mentioned distinction, which is also identical with that of azotised and non-azotised bodies. In order to give some indication of the state of confusion which existed, even in this most elementary proposition of dietetics, previous to that distinction being made, it may not be more than necessary to mention the idea of that classical author. Dr. Proutf, that the nutritive power is in direct pro- portion to the quantity of carbon. At the present day not a single fact is known which can support the idea of the animal body being able to form azotised from non-azotised substances, —possibly, under the influence of ammonia or of nitrogen from the atmosphere; on the contrary, all experiments, as well as daily observation, seem to prove the absolute neces- sity of azotised food for the preservation of the individual. Chemistry has likewise demonstrated the presence of a more or less high, but constant proportion of nitrogen in all the tissues and fluids of the animal body, while in all those sub- stances which, according to our modern ideas, are the most nutritive, namely, the pi'oteine compounds, the carbon is pre- sent in medium quantity. Those substances esteemed by Prout the most nourishing, because richest in carbon, as the fats and oils, must be altogether excluded from the list of re- productive bodies, except in so far as fatty matter is necessary to the formation of animal cells. The chemical physiologist could make use of the theory of Prout, in measuring the fitness of the bodies necessary to respiration, if along with * Coniinunicatcd by the Authors. t See Mayo’s Outlines of Human Physiology, p. 206, second edition. London, 1829. B