Page:Popular Science Monthly Volume 61.djvu/422

416 phenomena which are like all others bound to a definite material substratum called the psychoplasm. In this sense our view is materialistic. The processes in the lower forms of soul life, excitability, reflex movement, sensibility (Empfindlichkeit) and the impulse of self-preservation are directly conditioned by physiological processes in the plasm of their cells, by physical and chemical changes, which may be explained partly by heredity, partly by adaptation. The same may be said of the higher forms of soul life, for they have developed from the lower forms.

A study of comparative psychology and folk psychology, of ontogenetic and phylogenetic psychology, will show that organic life, in all its gradations, develops from the same forces of nature, from the physiological functions of sensation and movement. The plasm is the indispensable bearer of the psyche. The psyche, or soul, is not a separate being; the term psyche or soul is a collective term for the sum-total of the psychic functions of the plasm. In this sense the soul is a physiological abstraction, like the concept metabolism or generation. The 'soul' can not function without a certain chemical and physical composition of the psychoplasm.

All living organisms are sensitive (empfindlich); they distinguish the states of the surrounding world and react upon the same by certain changes within themselves. Light, heat, mechanical and chemical processes in the environment, act as stimuli upon the sensitive psychoplasm and cause changes in its molecular composition. There is an ascending scale of soul life, from the simplest forms of organic life where the entire protoplasm is sensitive and reacts, down to the most developed form, where we have a centralized nervous system and conscious sensation, the highest psychic function. We have cellular ideas, histonal ideas, unconscious ideas of the ganglionic cells, conscious ideas in brain cells, all of them being physiological functions of their psychoplasm. Only on the highest stages of animal organism does consciousness develop as a special function of a particular central organ of the nervous system. When the ideas become conscious, and when certain brain centers become highly developed, making possible an extensive association of conscious ideas, the organism becomes fitted to perform the highest functions which we characterize as thinking and deliberation, understanding and reason. We have the same stages in the development of memory and the association of ideas. There are many psychic products of this association of ideas, among them the unity of consciousness. Reason, the instincts, the emotions and the will are explained similarly. All these phases of psychic life are at first unconscious, all are functions of more or less complicated forms of organic matter, and all are subject to physical laws. The great riddle