pheral nerve-system, are developed from sense-organs
and muscles. But it is admitted that all these different soul-organs
with their characteristic properties have originated from single cells
through the division of labour (differentiation); and the nerves and
muscles especially have been developed by differentiation from the
neuro-muscular cells. The cells from which all these different
nerve-cells, muscle-cells, mind-cells, and so forth, are derived, are
originally the simple neutral cells of the epithelium of the ectoderm
or exterior germ-layer, and these cells, again, like all the cells of
many-celled animal bodies, originated in the repeated division of one
single original cell, the ovum-cell.

The individual development or ontogenesis of each of these many-celled
animal-forms, brings this histological process of development so
clearly and evidently before our eyes that we can but directly infer
from it the truth of the phylogenesis, or gradual historical evolution
of the soul-organs. The association of cells and the division of
labour among them are the modes by which, in the first instance, the
compound many-celled organism has originated, historically, from the
simple one-celled organism. And an impartial comparative consideration
teaches us in the clearest way that a functional-activity of the
soul-cells exists in the lowest one-celled animals as well as in the
highest and many-celled; in the infusoria as well as in man. Volition
and sensation, the universal and unmistakable signs of soul-life, may
be observed among the former as well as in the latter. Voluntary
motion and conscious sensation (of pressure, light, warmth, &c.) come
under our observation so undoubtedly in the commonest forms of
infusorial animals--for instance the Ciliata, that one of their most
persevering observers, Ehrenberg, asserted undeviatingly to the day of
his death that all Infusoria must possess nerves and muscles, organs
of sense and of soul, as well as the higher animals.

It is well known that the enormous advance which our science has lately
made in the natural history of these lowest organisms culminates in the
statement--clearly made by Siebold thirty years since, but only recently
"ascertained as proved"--that these minute creatures are _one-celled_,
and that in the case of these infusoria one single cell is capable of
all the various vital functions--including soul-functions--which in the
zoophytes (plant-animals), as the hyd