from the tail,
thus producing twins. The two sections came apart, however, in a very
few seconds after their departure from the colony. I am inclined to
believe that this deviation from the normal was due to accident;
probably to manipulation. This annelid is really "many in one" until the
very moment of division; the alimentary canal, nerves, blood-vessels,
etc., extend in unbroken continuity from the head of the parent worm to
the tail of the last section. In every fourth (sometimes fifth) ring two
round, dark-colored spots will be observed; these spots are ocelli, and
some of them eventually become the eyes of young worms. These organs
even in their embryonic state possess sight, for they have special
nerves and pigment-cells; they can differentiate between light and
darkness.

The snail carries its eyes in telescopic watch-towers. This animal is,
for the most part, nocturnal in its habits, and, since prominent and
commanding view points are assigned to its organs of sight, one would
naturally expect to find a comparatively high degree of development in
them; and this supposition is correct. The eyes of the creature are in
the extreme tips of its "horns," and consist of (1) a cornea, (2) a
lens, and (3) a retina. Lubbock is rather disposed to decry the visual
powers of the snail;[10] my conclusions, drawn from personal
observations, are, however, directly the opposite. The position of the
eyes at the extreme tips of the horns naturally indicates that they
subserve a very useful purpose; otherwise they would not have attained
such prominence and such a high degree of development. Actual
experimentation declares that the garden snail can see a moving white
object, such as a ball of cotton or twine, at a distance of two feet. In
my experiments I used a pole ten feet in length, from the tip of which a
white or dark ball was suspended by a string. The ball was made to
describe a pendulum-like movement to and fro in front of the snail on a
level with the tips of its horns. Time and again I have seen a snail
draw in its horns when it perceived the white ball, to it an unknown and
terror-inspiring object. I have likewise seen it change its line of
march, and proceed in another direction, in order to avoid the
mysterious white stranger dancing athwart its pathway. Dark-colored
objects are not so readily perceived; at least, snails do not give any
evidence of having seen them until they are brought within a foot of the
creatu