.
160
G. H. PARKER
THE
GASTROPOD
FOOT
AS
A
LOCOMOTOR
ORGAN
Locomotion by the gastropod foot, is not dependent upon .
ciliary action but is a muscular operation as shown by Dubois
'
and Vlès (’07).
The precise way in which the movements of locomotion are accomplished can best be made out by examining good
examples of direct and retrograde movement.
The rst is well
in Helix pomatia and Limax maximus; the second in
Chiton tuberculatus and Dolabrifera virens.
'
In an expanded and actively creeping Helix pomatia, the foot
may measure as much as seven to eight centimeters in length
by two and a half in width.
Over this a succession of transverse,
_
_
dark—brownish waves run from posterior to anteriOr.
At any
*
instant there may
be as many as ten or a dozen such waves on the
_
foot.
Each wave is separated from its neighbor by a space equal
to about three—times its own thickness.
The waves travel over
theioot in about thirty seconds, or at a rate of a centimeter in
‘
Ï
-
seVen to eight seconds.
These records, taken from a normal in—
dividual, agree fairly well with.those given by Bohn (’02) and by
_Biedermann (’05).
'
As the snail creeps, "it spreads frOm the mucous gland at the an—
…Ï
,_
-
'
terior edge of its foot a broad path of shine over which it makes
its way.
An activé snail marks its course in this manner by a
long track of
,
A Somewhat exhausted snail, when placed
_‘_
"
upon an appropriate substrate, will almost alWays creep far enough
path that will subtend the Whole Ofits foot, after
.
'
WhiCh it
If it is removed to another position, .
-
1tw1ll usually repeat this Operation, but it will
creep' far—_
,
'!
connected with the effectu‘al
taChment of itsî_f‘oot to the Substrànte.
_
‘
__
'
' _
Lmtn Helix.hke that in other pulmonaté‘è“(Kükëh
inséparable from
WaVe mOVementoflts
its fôotâ, almost1mmed1aæïäf
160
G. H. PARKER
THE
GASTROPOD
FOOT
AS
A
LOCOMOTOR
ORGAN
Locomotion by the gastropod foot, is not dependent upon .
ciliary action but is a muscular operation as shown by Dubois
'
and Vlès (’07).
The precise way in which the movements of locomotion are accomplished can best be made out by examining good
examples of direct and retrograde movement.
The rst is well
in Helix pomatia and Limax maximus; the second in
Chiton tuberculatus and Dolabrifera virens.
'
In an expanded and actively creeping Helix pomatia, the foot
may measure as much as seven to eight centimeters in length
by two and a half in width.
Over this a succession of transverse,
_
_
dark—brownish waves run from posterior to anteriOr.
At any
*
instant there may
be as many as ten or a dozen such waves on the
_
foot.
Each wave is separated from its neighbor by a space equal
to about three—times its own thickness.
The waves travel over
theioot in about thirty seconds, or at a rate of a centimeter in
‘
Ï
-
seVen to eight seconds.
These records, taken from a normal in—
dividual, agree fairly well with.those given by Bohn (’02) and by
_Biedermann (’05).
'
As the snail creeps, "it spreads frOm the mucous gland at the an—
…Ï
,_
-
'
terior edge of its foot a broad path of shine over which it makes
its way.
An activé snail marks its course in this manner by a
long track of
,
A Somewhat exhausted snail, when placed
_‘_
"
upon an appropriate substrate, will almost alWays creep far enough
path that will subtend the Whole Ofits foot, after
.
'
WhiCh it
If it is removed to another position, .
-
1tw1ll usually repeat this Operation, but it will
creep' far—_
,
'!
connected with the effectu‘al
taChment of itsî_f‘oot to the Substrànte.
_
‘
__
'
' _
Lmtn Helix.hke that in other pulmonaté‘è“(Kükëh
inséparable from
WaVe mOVementoflts
its fôotâ, almost1mmed1aæïäf