This mathematical discrimination between classes, types, dimensions is of the utmost importance in the natural sciences, because of the transmutation of species. To adjust the Darwin theory to dimensionality is a somewhat more difficult problem; it involves the concept of the “continuum”; but with the modern theory of de Vries, these things are self evident. If animals really progress, which is doubtful because they are an older form of life than humans and they have not shown any noticeable progress to the knowledge of man, their progress is so small in comparison with man’s that it may be said, in mathematical terms, to be _negligible_ as an infinitesimal of higher order. 10 It must be remembered here that our world is, first of all, a dynamic conglomeration of matter and energy, which to-day, as well as in the first period of primitive organic life, took and takes different known and unknown forms. One of these forms of energy is the chemical energy, with its tendency to combinations and exchanges. Different elements act in different ways. The history of the earth and its life is simply the history of different chemical periods, with different transformations of energy. A strange fact is to be noticed about nitrogen. Nitrogen chemically has an exceptional inertness toward most other substances, but once it is a component part of a substance, almost all of these combinations are a very powerful source of energy, and all of them have a very strong effect upon organic life. Nitric acid acts through oxidation, the substances are burned up by the oxygen given off from the acid. Nitric acid occurs in nature, in a combination called nitrates. From the soil the nitrates pass into the plant. Nitrite of amyl acts upon our organs in a most violent and spasmodic way. Nitrous oxide is the so-called laughing gas.