prehend my meaning when discussing _conscious_
mind.

A brief investigation of the anatomy, physiology, and psychology of the
medusa, or jelly-fish, will serve to illustrate the operations of the
unconscious mind as it is to be noticed in its reflex and "vegetative"
phases. The higher and more evolved phases of the unconscious mind will
not be discussed in this work, except incidentally, perhaps, as they may
appear, from time to time, as my propositions are advanced, and the
scheme of mental development is elaborated.

The medusa (the specimen that I take for study is a very common
fresh-water individual) has a well-developed nervous system. Its
transparent, translucent nectocalyx, or swimming-bell, has a central
nervous system which is localized on the margin of the bell, and which
forms the so-called "nerve-ring" of Romanes.[3] This nerve-ring is
separated into an upper and lower nerve-ring by the "veil," an annular
sheet of tissue which forms the floor of the swimming-bell, or
"umbrella," and through a central opening in which the manubrium, or
"handle," of the umbrella passes down and hangs below the margin of the
bell.

[3] Romanes, _Jelly-Fish_, _Star-Fish_, _and Sea-Urchins_, p. 16.

The nerve-ring is well supplied with epithelial and ganglionic
nerve-cells; their function is wholly reflex and involuntary; they
preside over the pulsing or swimming movements of the nectocalyx. This
pulsing is excited by stimulation, and is analogous, so far as movement
is concerned, to the peristaltic action of the intestines. Situated on
the margin of the bell are a number of very minute, round bodies, the
so-called "eyes." These eyes are supplied with nerves, one of whose
functions is volitional, as I will endeavor to show in my chapter on
Conscious Determination.

The manubrium, or handle, is also the centre of a nerve-system. Nerves
proceed from it and are spread out on the inner surface of the bell.
These nerves preside over digestion, and are involuntary. Certain
ganglia in the manubrium appear to preside over volitional effort. I
have never been able, however, to locate their exact position, nor to
determine their precise action. They will be discussed more fully in the
next chapter.

The nervous system of the nectocalyx is exceedingly sensitive,
responding with remarkable quickness to stimulation. When two or three
minims of alcohol are dropped into a pint of water in which one of these
creatures is swimming, the