Although the details of the classification proposed here are plausible, our knowledge of molecular biology, even in one cell-let alone for all the organism in nature is still far too incomplete to allow us to assert dogmatically that it is correct. (There is, for example, the problem of the chemical nature of the agent of the disease scrapie : see the articles by Gibbons and Hunter and Griffith. Nevertheless we know enough to say that a non-vial) example showing that the classification was wrong could be an important discovery.