s; but, when it is ascertained to
be the first creature in the entire Animal Kingdom in which a true
nervous system is to be found, then it becomes doubly interesting.

This protozoan has been a favorite subject for study with microscopists,
but Professor Clark of Harvard was the first observer to note and call
attention to its nerve-supply. Says he in his note calling attention to
this discovery:--

"The digestive and circulatory systems are the only parts of the
organization essential to life that are known to investigators; but
recently I have been led to believe that I have discovered the _nervous
system_, or at least a part of it, and that too in the very region of
the body where there is the most activity, and therefore more likely
than elsewhere to have this system most strongly developed. Immediately
within the edge of the disk (_bell_) there runs all around a narrow
faint band, which lies so close to the surface that it is difficult to
determine precisely that it is not actually superficial. From this band
there arise, at nearly equal distances all round, about a dozen
excessively faint thin stripes, which converge in a general direction
toward the mouth."[30]

[30] Clark, _Mind in Nature_, pp. 64, 65.

This band Professor Clark very correctly, as I believe, assumes to be a
part of Stentor's nervous system; for, with a medium high-power lens
(x500) I have been able to make out ganglionic enlargements both in the
circular band and in the stripes. These ganglia are the brain of this
infusorian. When the animalcule is stained with eosin, the nervous
system can very readily be made out and followed throughout all of its
ramifications.

On one occasion, while I was studying the contractile vesicle (heart) of
one of these animalcules, I saw it evince what seemed to me to be
unquestionable evidences of conscious determination.

Just above the creature, which was resting in its tube (it builds a
gelatinous tube into which it shrinks when alarmed or disturbed in any
way), there was a bit of alga, from which ripened spores were being given
off. Some of these spores were ruptured (probably by my manipulations) and
starch grains were escaping therefrom.

The Stentor, from its location below the alga, could not reach the
starch grains without altering its position. I saw it elevate itself in
its tube until it touched the starch grains with its cilia. With these
it swept a grain into its mouth, and then sank down i