Habit and intelligence: a series of essays on the laws of life and mind / by Joseph John Murphy.

  • Joseph John Murphy
Date:
1879
Catalogue details

Licence: Public Domain Mark

Credit: Habit and intelligence: a series of essays on the laws of life and mind / by Joseph John Murphy. Source: Wellcome Collection.

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    [chap. by melting away below, and gaining material in the snow that descends from above. Tbe word accretion sutficiently describes the deposit of new material to which is due the increase of a glacier, or a crystal, or any other inorganic growth. But there is this remarkable difference between organic and in- organic growth, that the accretion by which an inorganic mass grows is superficial: in the case of an organism, on the contrary, it is interstitial. And this is connected with a still profounder difference; namely, that new substance, in the act of becoming part of the substance of an organism, has a change wrought upon it by the agency of the organism itself, which makes it similar to the rest of the substance of the organism in chemical and mole- cular constitution. This process is what is called assimilation. The power of growth by assimilation appears essential to life : and the parallel process of waste is general, if not absolutely universal, among living beings.^ Everyone knows that waste is constantly going on from animalsi and it has been ascertained that vegetables, as well as animals, are constantly giving off carbonic acid, which can only come from the waste of their substance. We thus conclude that a living organism is con- stantly losing substance by waste; and if, among the lowest organisms, there are any exceptions to this law, there are cer- tainly no exceptions whatever to the law that a living organism acquires new substance which it transforms into its own substance by assimilation. This relation between life and matter has been usually regarded as the most important if not the only essential character of * If th(sre are any exceptions to the univer.sality of the process of waste, they can be only among the lowest organisms. “In the process of putrefaction, the researches of Pasteur have shown that so far from oxygen being necessary to the life of the simple living beings concerned, tliere are certain forms of infusoria which not only pass their lives without oxygen, but are killed by its presence. ”— (Beale’s edition of Todd and Bowman’s Physiology, p. 19.) What Pasteur here regards as infusoria must, I think, bo rather vegetable than animal. But whether this is so or not, it is not easy to see how waste can go on in organisms that never come in contact with ox3’gcn, and where, consequently, oxidation is impossible.
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