164
Ï
.
G. H PARKER .
.
it can be— seen with distinctŒss., If the anterior part of the
foot«of this slug be applied to' a glass surface, the pedal waves
appear quickly over the whole foot.
On inspecting the portion
'
of the foOt notyet in contact with
glass, the waves can be
_
’
identied as dark bands alternating— with light areas.
Qn examin—
_
ing.from the side the portion of the foot not yet in contact with
glass, it can be clearly seen that the waves are concavities
;
'
in the foot as compared with the areas between the waves. I
;
am, therefore, entirely convinced that, contrary to the opinion
expressed by Biedermann and others, the pedal wavesof the gas—
tropodsare concavities and not convexities on the foot. In these
.
,
concavities, which are probably lled with the more uid portiOn
-
Ï '
ofthe mucus, the foot
forward, the rest of this organ being
,
temporarin at a standstill.
'
—_
, —
.—
'
‘—
_
The mechanical advantage of this-arrangement must be obvious. ‘
_
sriailis attached to the substrate chiey by adhesion to the
denser:mucus.* This attractive force is- overcome by drawing
certain parts of the foot, the region of the waves, away fromthe
substrate: These parts are then in a positionÏto' move with re:—f duced; resistance and, are momentarily
while the. ‘
"
on the rest of its foOt_} . As this release from
”
,
adhesion is;propagated…asa wave overthe whole ofth;ä:foOt, this
t0_gethen withfthe rest of the shailf, is Jeventuà.llÿ
movedforwrd? At rst
a mghtseemthat sucha
WâV€ movement Couldmtmoduœ soumfarmamomnassnas
ShOWbut it mustbe 1"ermŒ@ered thattheumformüyafthæ
mtS@nth€b0dÿmreadTedŒt&ntfmmtheftarereadæd
adn“ïüadY‘3‘3dŒtwta1t“t‘S®furboäy11keîshehca
ShWat1nWb1@hmcmaSWl‘ûhthät@furfeetmalmœt
°mm“@“SÏYUrmÏnf&0taüamastrpWltha1ær
HatedlTectsmgï@W&vewnthæftwu1dalmstexactlyle
Ï
.
G. H PARKER .
.
it can be— seen with distinctŒss., If the anterior part of the
foot«of this slug be applied to' a glass surface, the pedal waves
appear quickly over the whole foot.
On inspecting the portion
'
of the foOt notyet in contact with
glass, the waves can be
_
’
identied as dark bands alternating— with light areas.
Qn examin—
_
ing.from the side the portion of the foot not yet in contact with
glass, it can be clearly seen that the waves are concavities
;
'
in the foot as compared with the areas between the waves. I
;
am, therefore, entirely convinced that, contrary to the opinion
expressed by Biedermann and others, the pedal wavesof the gas—
tropodsare concavities and not convexities on the foot. In these
.
,
concavities, which are probably lled with the more uid portiOn
-
Ï '
ofthe mucus, the foot
forward, the rest of this organ being
,
temporarin at a standstill.
'
—_
, —
.—
'
‘—
_
The mechanical advantage of this-arrangement must be obvious. ‘
_
sriailis attached to the substrate chiey by adhesion to the
denser:mucus.* This attractive force is- overcome by drawing
certain parts of the foot, the region of the waves, away fromthe
substrate: These parts are then in a positionÏto' move with re:—f duced; resistance and, are momentarily
while the. ‘
"
on the rest of its foOt_} . As this release from
”
,
adhesion is;propagated…asa wave overthe whole ofth;ä:foOt, this
t0_gethen withfthe rest of the shailf, is Jeventuà.llÿ
movedforwrd? At rst
a mghtseemthat sucha
WâV€ movement Couldmtmoduœ soumfarmamomnassnas
ShOWbut it mustbe 1"ermŒ@ered thattheumformüyafthæ
mtS@nth€b0dÿmreadTedŒt&ntfmmtheftarereadæd
adn“ïüadY‘3‘3dŒtwta1t“t‘S®furboäy11keîshehca
ShWat1nWb1@hmcmaSWl‘ûhthät@furfeetmalmœt
°mm“@“SÏYUrmÏnf&0taüamastrpWltha1ær
HatedlTectsmgï@W&vewnthæftwu1dalmstexactlyle