4 i 6 POPULAR SCIENCE MONTHLY. 



phenomena which are like all others bound to a definite material sub- 

 stratum called the psychoplasm.* In this sense our view is material- 

 istic. The processes in the lower forms of soul life, excitability, reflex 

 movement, sensibility (Empfindlichlceit) 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 gener- 

 ation. The 'soul' can not function without a certain chemical and 

 physical composition of the psy chop] asm. 



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 psycho- 

 plasm 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 con- 

 scious 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. Eeason, 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 



* See also ' Monismus,' p. 21. 



