122 THE EIDDLE OF THE UNIVERSE. 



The evolutionary scale of memory is closely 

 connected with that of presentation ; this extremely 

 important function of the psychoplasm — the condition 

 of all further psychic development — consists essen- 

 tially in the reproduction of presentations. The 

 impressions in the bioplasm, which the stimulus 

 produced as sensations, and which became presenta- 

 tions in remaining, are revived by memory; they 

 pass from potentiality to actuality. The latent 

 potential energy of the psychoplasm is transformed 

 into kinetic energy. We may distinguish four stages 

 in the upward development of memory, corresponding 

 to the four stages of presentation. 



I. Cellular memory. — Thirty years ago Ewald 

 Hering, in a thoughtful work, showed " memory to 

 be a general property of organised matter," and 

 indicated the great significance of this function, " to 

 which we owe almost all that we are and have." Six 

 years later, in my work on The Perigenesis of the 

 Plastidule, or the Undulatory Origin of the Parts of 

 Life, I developed these ideas, and endeavoured to base 

 them on the principles of evolution. I have attempted 

 to show in that work that unconscious memory is a uni- 

 versal and very important function of all plastidules ; 

 that is, of those hypothetical molecules, or groups of 

 molecules, which Naegeli has called micella, others 

 bioplasts, and so forth. Only living plastidules, as 

 individual molecules of the active protoplasm, are 

 reproductive, and so gifted with memory ; that is the 

 chief difference between the organic and inorganic 

 worlds. It might be stated thus : "Heredity is the 

 memory of the plastidule, while variability is its compre- 

 hension." The elementary memory of the unicellular 

 protist is made up of the molecular memory of the 



