extremely fine threads, like the electric wires at a large telegraphic
centre, cross and recross in the delicate protoplasm of the nerve
cell, and pass out in the branching processes which proceed from it
and put it in communication with other nerve-cells or nerve-fibres (a,
b). We can only partly follow their intricate paths in the fine matter
of the body of the cell.

Here we have a most elaborate apparatus, the delicate structure of
which we are just beginning to appreciate through our most powerful
microscopes, but whose significance is rather a matter of conjecture
than knowledge. Its intricate structure corresponds to the very
complicated functions of the mind. Nevertheless, this elementary organ
of psychic activity--of which there are thousands in our brain--is
nothing but a single cell. Our whole mental life is only the joint
result of the combined activity of all these nerve-cells, or
soul-cells. In the centre of each cell there is a large transparent
nucleus, containing a small and dark nuclear body. Here, as elsewhere,
it is the nucleus that determines the individuality of the cell; it
proves that the whole structure, in spite of its intricate
composition, amounts to only a single cell.

(FIGURE 1.8. Unfertilised ovum of an echinoderm (from Hertwig). The
vesicular nucleus (or "germinal vesicle") is globular, half the size
of the round ovum, and encloses a nuclear framework, in the central
knot of which there is a dark nucleolus (the "germinal spot").

FIGURE 1.9. A large branching nerve-cell, or "soul-cell," from the
brain of an electric fish (Torpedo), magnified 600 times. In the
middle of the cell is the large transparent round nucleus, one
nucleolus, and, within the latter again, a nucleolinus. The protoplasm