effort is its own tendency to produce a result other than
itself, and this conforms to our general definition of
conation and distinguishes it from reflex action, in which,
as in everything mechanical, the result is indifferent.

The simplest form of conation then seems to be action
directed vaguely to a change of conditions, persisted in or
varied until new and more suitable conditions are obtained.
Such action is not purpose because it does not clearly
foresee these conditions, but it is conation because it is
determined by the contrast between the existing state of
the organism and the relief which in fact it tends to bring
about. Conation at this stage is found to all appearance
among unicellular organisms. Thus Paramecium, in
normal conditions, swims gently forward, absorbing food
by whirling its cilia. If it encounters a solid body it backs
a little, then swings round through an angle of varying
magnitude and advances again. If again it strikes the
object, the process is repeated and various directions are
tried, so that in the end, if there is any egress, it is found.
The animal seems in a fashion to explore the object, but
the exploration is indirect and persists through the inhi-
bition of repeated errors. Paramecia will behave in the
same way to a drop of many chemical solutions. It swims
up to the edge of the drop if not too strong, and then
reacts in the way described, so that, seen through the
microscope, the drop remains empty, while the weaker
solution around is crowded with Paramecia. This occurs
when the reaction to the drop is what is called negative.
The converse case has a special interest. When a drop of
weaker solution is contained in one of a stronger the
Paramecia appear to be positively attracted to it, and
superficially it looks as though they swam deliberately to
the spot preferred, which is soon crowded with Paramecia,
while the rest of the liquid is empty. But in reality the
result is only reached by an indirect method and the
continued repetition of the negative reaction. The organ-
ism swims at random, but any individual which enters the
drop proceeds across it until it reaches the edge of the
stronger solution. There it gives the avoiding reaction
and starts off swimming in a new direction till it reaches

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