Essentials of human physiology for medical students / by D. Noël Paton.

  • Paton D. No︠︡l (Diarmid No︠︡l), 1859-1928.
Date:
1903
Catalogue details

Licence: In copyright

Credit: Essentials of human physiology for medical students / by D. Noël Paton. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    Such complex substauces as sugar very readily break down and liberate energ}\ For instance, formate of lime breaks into carbonate of lime, carbonic acid and hydrogen, under different conditions. First, under the influence of certain bacteria, minute living organisms resembling yeast in many particulars ; second, under the influence of some substance contained in the bacteria after they are killed ; and lastly, in the jjresence of finely divided iridium, rhodium, and ruthenium—i.e., the same change is brought about by a living organism, by a substance contained in it, and by a metal. Hence mere vibrations of molecules occurring in different ways and in different substances may be sufficient to bring about these changes, and however the change is brought about the result is to set free energy. Living yeast differs from these dead substances simply in the fact that it uses the energy liberated from the glucose. In virtue of this, the yeast has the power of repair and of growth. But protoplasm is also constantly breaking down, and if yeast be kept at a suitable temperature in water without any supply of material for construction, it gives off carbon dioxide and decreases in bulk on account of these disinte- grative changes. These are as essential a part of the life of living matter as the building-up changes, and it is only when they are in progress that the latter are possible. Protoplasm (living matter) is living only in virtue of its metabolism, constant chemical changes, and these changes are on the one hand destructive (katabolic), on the other constructive {anabolic). Living matter thus differs from dead simply in this respect, that side by side with destructive changes, constructive changes are always going on. Hence our conception of living matter is not of a definite chemical substance, but of a substance never two seconds the same, constantly undergoing internal changes. Hoppe-Seyler expresses this by saying, “ The life of all organisms depends upon, or one can almost say, is identical with a chain of chemical changes.” Foster puts the same idea in more fanciful language, “ We may speak of proto-