it gives for the application of the law of mass action (and other physicochemical laws) to phenomena which usually form the material for psychological speculation. To make possible a better understanding of my lecture, let me mention briefly how I came to hold the views set forth here.
The writings of the metaphysicians on the will in nature led me to an experimental analysis of the nature of will. When in my first years at the university Munk's investigations on the cerebral cortex fell into my hands I believed that here was a starting point toward my goal. Munk stated that he had succeeded in proving that every memory image in a dog's brain is localized in a particular cell or group of cells and that any one of these memory images can be extirpated at will. Five years of experiments later with extirpations in the cerebral cortex proved to me without doubt that Munk had become the victim of an error and that the method of cerebral operations can really give only data concerning the nerve connections in the central nervous system but teach practically nothing about the dynamics of brain processes.
A better way seemed to lie in the comparative psychology of the lower animals in which the memory apparatus is developed but slightly or not at all. It seemed to me that some day it must become possible to trace the apparently random movements of animals back to general laws, just as definitely as it has been done for the movements of the planets, and that the word "animal will" is only the expression of our ignorance of the forces which prescribe for animals the direction of their apparently spontaneous movements just as unequivocally as gravity prescribes the movements of the planets. For if a savage could directly observe the movement of the planets and should begin to ponder over it, he would probably come to the conclusion that a "will action" guides the movements of the planets, just as a chance observer is inclined to assume that "will" causes animals to move in a given direction.
The scientific solution of the problem of will seemed to consist in finding the forces which unequivocally determine the movements of animals, and in discovering the laws according to which these forces act. Experimentally, the solution of the problem of will must take the form of forcing, by external means, any number of individuals of a given kind of animal to move in a definite direction by means of their locomotor apparatus. Only if this succeeds have we the right to assume that we know the force which under certain conditions seems to a layman to be the will of the animal. But if only a part of the number moves in this definite direction and another does not, then we have not succeeded in finding the force which in a given case determines unequivocally the direction of movement.
One other point should be observed. If a sparrow flies down from
