A manual of elementary zoology / by L.A. Borradaile.

  • Lancelot Alexander Borradaile
Date:
1930
Catalogue details

Licence: In copyright

Credit: A manual of elementary zoology / by L.A. Borradaile. Source: Wellcome Collection.

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    Life, like all other processes that go on in material bodies, requires energy. It differs from some IfhLiteergy such processes in the way in which its energy is obtained, and from all of them in the way in which its energy is directed. The energy of the process which goes on in a boiling kettle is imparted to it con- tinually from without by the fire. The energy of the process which goes on in a clock is stored in it, but has been imparted to it by mechanical action from without, in the winding of the spring. The energy of the processes which go on in a mass of radium, or in a cartridge which explodes, is derived from the disintegration of part of the substance of the radium or the cartridge itself. The energy of the life of a living being is likewise derived from the disintegration of substances in itself. But life differs from the other processes, and from all processes that go on in lifeless things, in that its energy is liberated in such a way as to tend to the preservation and increase of the thing in which it goes on—that is, of the living being. It is spent, for instance, in removing from danger, infighting enemies, in seeking and taking food, in producing young. The mode in which the living body avails itself of energy contained in its own substance depends upon the following facts. Whenever atoms unite to form molecules, energy is set free, and the stabler the molecules formed,' the greater, almost invariably, is the amount of energy liberated at their formation. The same amount of energy must be used to break up a molecule as was set free when it was formed. 1 he molecules that compose the sub- stances from which the body obtains its energy contain carbon, hydrogen, oxygen, and sometimes nitrogen and other elements, and are complex and relatively unstable and rich in energy. The body breaks down these mole- cules, uniting the carbon and hydrogen atoms with oxygen so as to form smaller and more stable molecules of carbon dioxide and water. The energy which is freed in the formation of the stabler molecules is so much greater than that which is required to break down those that are less stable that a large balance of energy is set free, and becomes available for the work of life. Sometimes the oxygen used in this process is entirely derived from that
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