Physiological and pathological researches / being a reprint of the principal scientific writings of the late T. R. Lewis ... Arranged and edited by Sir William Aitken ... G. E. Dobson ... and A. E. Brown.
- Lewis, T. R. (Timothy Richards), 1841-1886.
- Date:
- 1888
Licence: Public Domain Mark
Credit: Physiological and pathological researches / being a reprint of the principal scientific writings of the late T. R. Lewis ... Arranged and edited by Sir William Aitken ... G. E. Dobson ... and A. E. Brown. Source: Wellcome Collection.
Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.
824/920 (page 642)
![derived from the vegetable kingdom, seeing that, more or less directly, herbivorous animals constitute the prey of the carnivora. As organised food substances usually contain the requisite proportion of the unorganised, it seems unnecessary, in a note of this kind, to give in detail the amount of the inorganic constituents of individual diet scales. 3. It will, therefore, be necessary to consider specially the leading characteristics of organised food stuffs. These may be classified under two principal headings —those which contain nitrogen and those which do not. The nitrogenous group of compounds is very commonly referred to as albuminates [also proteids] from the circumstance that albumen forms the most important alimentary constituent of the group—a sub- stance which is directly derivable both from animals and plants. The non-nitrogenous group is ordinarily sub-divided into (a) carbo-hydrates, the most important compounds of which are starch and sugar ; (6) fats. 4. In the present memorandum the sum of the ingredients in all the principal scales of diet given in the text will be found resolved into these three great alimen- tary principles; but for the sake of conciseness, and as tending to simplicity of arrangement, the nutritive value of the individual ingredients given in the series of the appended dietary tables has been expressed in terms of nitrogen and carbon only. This does not imply that these two elements are assimilated when in an uncombined condition, but that the quantities of the special ingredients cited in any particular diet may, in the laboratory, be resolved into so many grains of nitrogen and carbon. Computations of the amount of these two elements in the different alimentary sub- stances furnish a convenient and simple index of the approximate nutritive value of a combination of food stuffs, seeing that, as the late Dr. Parkes expressed it, the phenomena of nutrition are chiefly owing to the various chemical interchanges of nitrogen and carbon (and in some instances of hydrogen with oxygen). 5. Speaking generally, the chief functions of the nitrogenous principles of food seem to be the development and renovation of the tissues, and the acceleration of the chemical changes which take place in them; whilst the non-nitrogenous, or carbon- aceous, material furnishes the principal source of mechanical force ; or, as Pavy has it, the former may be spoken of as holding the position of the instrument of action, while the other supplies the motive power. The quantity and the proportions of these proximate alimentary substances which are required to maintain individuals in health, the particular part which each proximate aliment plays in the animal economy, and the relative proportions in which they should be given during periods of rest and of activity, are questions regarding which there is still far too much uncertainty to admit of any definite statement being made. Until recently, the view, advocated by Liebig, was generally held that physical exertion involved a positive waste of muscular tissue, and that, consequently, an increase of the flesh-formers, as the albuminate constituents of the food were described, was required in proportion to the amount of mechanical labour which the body was called upon to lindergo. As a result of this](https://iiif.wellcomecollection.org/image/b21296996_0828.jp2/full/800%2C/0/default.jpg)
