If, as chemists and biologists then believe, protoplasm is a compound which stands at the head of the organic series, and if, as is the fact, chemists are each year succeeding in making higher and higher members of the series, it is an easy assumption that some day they will be able to make the highest member of the series.  Further, it is a well-known fact that simple chemical compounds have simple physical properties, while the higher ones have more varied properties.  Water has the property of being liquid at certain temperatures and solid at others, and of dividing into small particles (i.e., dissolving) certain bodies brought in contact with it.  The higher compound albumen has, however, a great number of properties and possibilities of combination far beyond those of water.  Now if the properties increase in complexity with the complexity of the compound, it is again an easy assumption that when we reach a compound as complex as protoplasm, it will have properties as complex as those of the simple life substance.  Nor was this such a very wild hypothesis.  After all, the fundamental life activities may all be traced to the simple oxidation of food, for this results in movement, assimilation, and growth, and the result of growth is reproduction.  It was therefore only necessary for our biological chemists to suppose that their chemical compound protoplasm possessed the power of causing certain kinds of oxidation to take place, just as water itself induces a simpler kind of oxidation, and they would have a mechanical explanation of the life activities.  It was certainly not a very absurd assumption to make, that this substance protoplasm could have this power, and from this the other vital activities are easily derived.

In other words, the formulation of the doctrine of protoplasm made it possible to assume that life is not a distinct force, but simply a name given to the properties possessed by that highly complex chemical compound protoplasm.  Just as we might give the name aquacity to the properties possessed by water, so we have actually given the name vitality to the properties possessed by protoplasm.  To be sure, vitality is more marvelous than aquacity, but so is protoplasm a more complex compound than water.  This compound was a very unstable compound, just as is a mass of gunpowder, and hence it is highly irritable, also like gunpowder, and any disturbance of its condition produces motion, just as a spark will do in a mass of gunpowder.  It is capable of inducing oxidation in foods, something as water induces oxidation in a bit of iron.  The oxidation is, however, of a different kind, and results in the formation of different chemical combinations; but it is the basis of assimilation.  Since now assimilation is the foundation of growth and reproduction, this mechanical theory of life thus succeeded in tracing to the simple properties of the chemical compound protoplasm, all the fundamental properties of life.  Since further, as we have seen in our first chapter, the more complex properties of higher organisms are easily deduced from these simple ones by the application of the laws of mechanics, we have here in this mechanical theory of life the complete reduction of the body to a machine.