We find the highest development of the animal cell-soul in the class of ciliata, or ciliated infusoria. When we compare their activity with the corresponding psychic life of the higher, multicellular animals, we find scarcely any psychological difference; the sensitive and motor _organella_ of these protozoa seem to accomplish the same as the sense-organs, nerves, and muscles of the metazoa. Indeed, we have found in the great cell-nucleus (_meganucleus_) of the infusoria a central organ of psychic activity, which plays much the same part in their unicellular organism as the brain does in the psychic life of higher animals. However, it is very difficult to determine how far this comparison is justified; the views of experts diverge considerably over the matter. Some take all spontaneous bodily movement in them to be automatic, or impulsive, and all stimulated movement to be reflex; others are convinced that such movements are partly voluntary and intentional. The latter would attribute to the infusoria a certain degree of consciousness, and even self-consciousness; but this is rejected by the others. However that very difficult question may be settled, it does not alter the fact that these unicellular protozoa give proof of the possession of a highly developed "cell-soul," which is of great interest for a correct decision as to the _psyche_ of our earliest unicellular ancestors. II. _The communal or cenobitic soul_ (_coenopsyche_): second stage of phyletic psychogenesis.--Individual development begins, in man and in all other multicellular animals, with the repeated segmentation of one simple cell. This _stem-cell_, the impregnated ovum, divides first into two daughter cells, by a process of ordinary indirect segmentation; as the process is repeated there arise (by equal division of the egg) successively four, eight, sixteen, thirty-two, sixty-four such new cells, or "blastomeres." Usually (that is, in the case of the majority of animals) an irregular enlargement sooner or later takes the place of this original regular division of cells. But the result is the same in all cases--the formation of a (generally spherical) cluster of heterogeneous (originally homogeneous) cells. This stage is called the _morula_ ("mulberry," which it somewhat resembles in shape). Then, as a rule, a fluid gathers in the interior of this aggregate of cells; it changes into a spherical vesicle; all the cells go to its surface, and arrange themselves in one simple layer--the _blastoderm_. The hollow sphere which is thus formed is the important stage of the "germinal vesicle," the _blastula_, or blastosphere.