CHAPTER IX - THE PHYLOGENY OF THE SOUL

Summary

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 (cœnopsyche): 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. Phylogeny 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 psychology to trace the stages of the historical development of the soul of man from the soul of the brute.