One of the most essential characteristics of living material—indeed, according to many, its most essential characteristic—is the fact that it is irritable. A living cell responds to sudden environmental changes (which we call stimuli), and typically a cell of a given sort responds in a definite and particular way no matter what the nature of the stimulation. Thus when a muscle cell is exposed to sudden heat, to sudden cold, to a sharp mechanical impact, to ultraviolet radiation, or to an electric current, it shortens. Similarly, a nerve fiber responds in its own characteristic way, and this response is independent of the nature of the stimulation. In general, mechanical impacts, ultraviolet radiation, electric shocks, and certain types of chemical substances are stimulating agents for many diverse types of protoplasm and they serve to arouse it to activity. The response of protoplasm to stimulation may be prevented by anesthetics. These are substances (or agents) which nullify the effect of a stimulus without killing or seriously injuring the protoplasm. The remarkable fact is that there are general anesthetics, substances which in much the same concentration can prevent protoplasmic activity in widely different protoplasmic systems. Many fat solvents, such as ether, are general anesthetics. Magnesium salts also behave as anesthetics for many different types of cells.

A kinetic theory of permeability is developed both for the case where the cell membrane is a distinct phase and where it is simply the interface between cell and environment. A general expression for the diffusion current of a substance across the membrane is derived, which depends on two “coefficients of permeability” rather than one. Solubility and adsorption theories of permeability are shown to be special cases of the formulas. The permeability coefficients are expressed in terms of the difference of potential energy of the diffusing substance in the two phases; for a membrane of finite thickness they also involve the thickness, and the diffusion coefficient of the solute in the membrane.

The claim of this communication is to present an outline of a program of research and development of thermodynamics. The scope of this and subsequent discussions will be “materialistic,” by which the author means a combination of both formal and experimental aspects.

We wish here to consider the theory of a population or system made up of individuals whose number and size change with time. As usual, the description of these changes will be referred to as the kinetics, whereas the description of the special circumstances under which unchanging (equilibrium) conditions subsist will be called the statics of the population. A third category, the conditions for a steady state, i.e., when the variables inside the system do not change, but linked variables outside (or at the boundary) do, will be described by what we shall call the rheostatics of the system. All three, statics, rheostatics, and kinetics are subdivisions of the general dynamics of the system.

The present paper deals with the determination of the size and charge of a single submicroscopic particle, measured in a small horizontal condenser of a diameter of approximately 8 mm., using the author's method first stated April 1910. To obtain the highest sensitivity, author used solid particles (spheres) of an order of magnitude under 3 × 10–5 cm. and found charges less than that of the electron. Various objections were raised against his findings, namely that the particles investigated were not spheres, and that their density was not that of the macroscopic substance, so that his findings of charges less than the electronic charge were merely imaginary. The author has succeeded in precipitating and measuring a particle after having observed it in the condenser under normal and also very high gas pressures. The particles were shown to be perfect spheres. A new method is indicated whereby it is possible to determine the size of sub-microscopic spheres by pushing together two equal spheres with a micromanipulator; the two diffraction disks overlap and render it very easy to determine the actual size. It is also possible to show that the density of each individual sphere is that of the macroscopic substance, since it can be computed easily from the velocity of fall at high gas pressures (according to Stokes' law). These two data being accurately determined, the author still found charges considerably less than the electronic charge, and the deviations are too great to be accounted for by errors of observation. The reason that the author has used a solid substance (red amorphous Se) and not oil, which is a liquid, was in the first place, that liquids evaporate, and therefore do not yield correct results, and secondly, because liquid spheres are not certain to preserve their sphericity when precipitated. Thus charges less than that of the electron are to be considered as actually existing.

According to generally accepted views every material body has always just as much North as South magnetism, meaning that the total value of the North and South magnetism is always zero (div H = 0). One says therefore that there is no “true magnetism”. A body directs itself in the direction of the magnetic lines of force like a compass needle but it does not move from its place. On the other hand, it is known that there are electrically charged bodies (positive or negative electric ions) which move in homogeneous electric fields along the lines of force. There is thus a preponderance of positive or negative electricity on ions. One says also that there exists “true electricity”. A movement of charged matter in a homogeneous field is called a current. Consequently until now electric currents were known to exist, but no magnetic currents.