CHAPTER IX. 

 THE PHYLOGENY OF THE SOUL. 



Gradual historical evolution of the human soul from the animal 

 soul. Methods of phylogenetic psychology. Four chief stages in 

 the phylogeny of the soul. I. The cell-soul (cytopsyche) of the 

 protist (infusoria, ova, etc.) : cellular psychology. II. The soul 

 of a colony of cells, or the cenobitic soul (coenopsyche) : psychology 

 of the morula and blastula. III. The soul of the tissue 

 (histopsyche) : its twofold nature. The soul of the plant. The 

 soul of the lower, nerveless animal. Double soul of the 

 siphonophora (personal and kormal soul). IV. The nerve-soul 

 (neuro-psyche) of the higher animal. Three sections of its psychic 

 apparatus : sense-organs, muscles, and nerves. Typical formation 

 of the nerve-centre in the various groups of animals. Psychic 

 organ of the vertebrate : the brain and the spinal cord. Phylo- 

 geny of the mammal soul. 



The theory of descent, combined with anthropological 

 research, has convinced us of the descent of our human 

 organism from a long series of animal ancestors by a 

 slow and gradual transformation occupying many 

 millions of years. Since, then, we cannot dissever 

 man's psychic life from the rest of his vital functions 

 — we are rather forced to a conviction of the natural 

 evolution of our whole body and mind — it becomes 

 one of the main tasks of the modern monistic psycho- 

 logy to trace the stages of the historical development 

 of the soul of man from the soul of the brute. Our 

 " phylogeny of the soul " seeks to attain this object; 

 it may also, as a branch of general psychology, be 



151 



