_
,
LOCOMÔTION IN GASTÈOPODS ‘
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“
_Ç
‘
the same type of movement as has been described for the specks
‘ '
.
,
in the foot of Helix.
In Limax the waves, however, 'are» light in ;
color, instead of being dark as in
and their surfaces,
‘
,
,
seen in the air, are marked with ne wrinkles transverse to the
_
,
longitudinal axis of the animal.
These wrinkles show that the
waves are regions of longidudinalcontraction, as has been main—
f
tained by most recent writers on this subject.
j
,
The chief error in most previous accounts of thelocomotion Of
,
the gastropod foot is found in the physical conguration as‘cribed
_
to the underside of this organ. 'Biedermann (’05, pp. 10,17)
‘
_
states that the waves are convexities onthe surface of the foot
and that they press more rmly against the substrate than does
_
.
the rest of the foot.
This view was adopted by von Uexkül‘l‘
'
’
(’O9, p. 187) in his discussion of gastropod locomotion.» In Helix
‘pomatia it is by no means easy to determine whether‘ the waves
,
_
,
are convexities or not, for the reason that they are at most Only
,
very slightly different in level from the general surface of the
‘
,
foot;
On inspecting by reflected light the free ventralsuace of
'
_
a part of a Helix foot over which waves
running, I was un—=
to tell with certainty whether the surfaCes of the Waves were
convex, concave, or at. If, however, the creepin‘g foot be closely
studied through
evidence of a ConcluSive.kind can be found;
If“, under these circumstances, a very. min—utevair bubble
‘
,
in the mucus under the snai—l is watchèd,itwill be seerito change
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.
its form and position slightly as-Ï-‘e‘ach Wave passes: o‘Ver= it; As
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'
‘
’
»
the wave approaches
it will
face
next the waVe and at times
_.
<
QÏ;‘
as the wave leaves it, it Wlll
in the opposite
'
dire‘ction and at tlmesfoowshgtlytheretieatmgwave The”
motions of the bubble areexactlythSethäfüSh©1dbeeXpe°ted
, ‘Pr0vided the:
“.
"
reve1seof whatwouideccmsupposmgthewaveplessedup0the
bubble
…
‘The