82 
NATURE) STUDY. 
Much may be learned about these creatures with keen 
eyes alone—that in land snails the shells are usually flat¬ 
tened, but elongated in water snails ; that the eyes of land 
snails and slugs are at the tips of the “feelers,” while at 
their base in water snails; the breathing orifice may be 
found on the right side of the slugs and land snails, open¬ 
ing and closing slowly, and many water snails may be seen 
coming to the surface to breathe. But the most deeply in¬ 
teresting thing about them is the way they walk, or move 
along. If a slug or snail is placed on a piece of wet glass, 
we can turn the glass as we please, and watch the flowing, 
“creeping” movement of the foot, or “creeping disk.” If 
we have a magnifying glass, so much the better. The wa¬ 
ter snails can be studied as they creep along the side of the 
jar, and, best of all, as they move along the surface of the 
water, making use of the under side of the same surface 
film that the water strider walks upon. Here, with a mag¬ 
nifier, the peculiar creeping movement can be seen to the 
very best advantage. If we are not too squeamish—and 
we shall not be when we realize what we are learning^—-we 
may moisten the back of the hand, or better still, the bare 
arm, and placing the slug or snail there may feel the ‘ ‘creep¬ 
ing” as the creature moves along. The sensation will nev¬ 
er be forgotten, for in this experiment we have felt, as 
wrell as seen, the oldest way of walking in the world. 
Many tiny creatures, as amoebae, many bacteria and the 
single cells of some plants move about in water without 
feet, or fins, or any appendages whatever—merely by a 
‘ ‘ creeping ’ ’ motion which is known as the • ‘ amoeboid 
movement.” This mode of motion has become highly 
specialized in the ‘ ‘ foot ” or “ creeping disk ’ ’ of the great 
multitude of snails, clams and other molluscs that still re¬ 
tain this first method of locomotion. But this thought is 
rather for grown-up folks than for children. Tor them, it 
will be enough, at present, to watch the slug move along 
the under side of a piece of glass, or the snail “ walk ” by 
help of the surface film that covers the water in the jar, al¬ 
though at the same time it will do them no harm to tell 
them that they are studying in that way the most old-fash¬ 
ioned of all the queer ways of walking. 
