Page:Defensive Ferments of the Animal Organism (3rd edition).djvu/28

cated substance of its specific properties. The disharmonious product is decomposed into indifferent by-products which are harmless to the cell. More energetic means are often employed, and the material is oxidized or reduced according to the special needs of the cell. Even in these simple forms of life it is probable that many substances are rendered harmless by combining to form fresh compounds, just as, in the metabolism of a more complicated organism, rearrangements of different kinds are undergone which alter such materials as are undesirable, so that they may be excreted in this form out of the body. Very often a given substance is incapable of combination, in which case it must first be so transformed by special processes as to be susceptible to combination. We thus see how the cells of the body oxidize, reduce, or decompose, until a product is reached that is capable of combination. There is no reason to doubt that unicellular organisms have similar means of defence at their disposal, but they are not so easily traced, owing to the fact that it is more difficult to add certain substances to a single cell, without damaging it, than it is in the case of a more complicated organism. The latter are able to modify profoundly the action of substances introduced by the mouth, owing to the fact that they are gradually absorbed. Further, these substances are considerably diluted in the lymph