The
Commonwealth of Cells.
Some Popular Essays on Human Physiology.
Essay I.
Living Matter.
Physiology is the study of life, and the thing of all others which the physiologist would like to discover is what life really is. If this were fully known, all physiological processes could probably be deduced from it, and disease, which is an interference with one or other of them, could be scientifically treated. So far he has not got beyond describing the consequences of life, and his deductions carry him no further than this: life is a property of a substance, protoplasm, and protoplasm can only continue to exist in the form of a cell.
This definition may seem a little cryptic to some people, and very shocking to others. ‘Life,’ many people are accustomed to say, ‘means the presence of a soul, and is supernatural; and as to its being a question of chemical composition, that is absurd. My being made of cells, too, will not account for my thinking.’ But when people dogmatize thus about what they have not considered, they usually find themselves landed in difficulties. They go so fast: the most spiritual of men is so dependent upon matter and its properties that his soul will speedily quit his body if he is prevented from breathing. And the reason of this is, that if he cannot get air, the chemistry of the cells of which his body is made becomes altered; he no longer consists of protoplasm, therefore he no longer lives. Life, that it may exist in a material world, must
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