ells possess the power of uniting with or assimilating other
cells, or fragments of cells, as they drift by and come into contact
with them; and that they absorb into their own substance such portions
as may be suitable, while the insufficiently elaborated portions--the
grains of inorganic or over-simple material--are presently extruded.
They thus begin the act of "feeding."

Another remarkable property also can be observed; for a cell which thus
grows by feeding need not remain as one individual, but may split into
two, or into more than two, which may cohere for a time, but will
ultimately separate and continue existence on their own account. Thus
begins the act of "reproduction."

But a still more remarkable property can be observed in some of the
cells, though not in all; they can not only assimilate a fragment of
matter which comes into contact with them, but they can sense it,
apparently, while not yet in contact, and can protrude portions of
their substance or move their whole bodies towards the fragment, thus
beginning the act of "hunting"; and the incipient locomotory power can
be extended till light and air and moisture and many other things can
be sought and moved towards, until locomotion becomes so free that it
sometimes seems apparently objectless--mere restlessness, change for
the sake of change, like that of human beings.

The power of locomotion is liable, however, to introduce the cell to
new dangers, and to conditions hostile to its continued aggregate
existence. So, in addition to the sense of food and other desirable
things ahead, it seems to acquire, at any rate when still further
aggregated and more developed, a sense of shrinking from and avoidance
of the hostile and the dangerous,--a sense as it were of "pain."

And so it enters on its long career of progress, always liable to
disintegration or "death"; it begins to differentiate portions of
itself for the feeding process, other portions for the reproductive
process, other portions again for sensory processes, but retaining the
protective sense of pain almost everywhere; until the spots sensitive
to ethereal and aerial vibrations--which, arriving as they do from a
distance, carry with them so much valuable information, and when duly
appreciated render possible perception and prediction as to what is
ahead--until these sensitive spots have become developed into the
special organs which we now know as the "eye" and the "ear." Then,
presently,