ECONOMY OF THE
161
salinity of water, food, oxygen, carbonic acid, water pressure,
currents, or sound.
They are only stimulated by, that is
the sh responds to, gentlè vibrations in‘the water of low
-
frequency, ‘six persecond. Hence we…can understand how
the blind shes in the caves, of Kentucky canavoid Obstacles.
The reex waves set up by, their own movements inform
them'when they approach too near the sides. Theoctinal
bats seem to have a similar
,
_
'
sense.
,
,
,
.
.
_-_se
,
…
Fishes living in a tank in
,
,
'
de
,,
'
.
an aquarium are guided by
'
'
,
the same means.
But if the
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.,
:' :
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'
water is violentlÿ disturbed,
, - '
they lose all Sense of dis—
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,f'
"
Ct”
tance and clash themselves
dû
.,‘—="' -".""
against the sides. In
_
…î_i
'
,
turbed waters, therefore, the
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'
ap
,.
lateral line, orgaris are of 110
"
‘
,
'uSe to the shes,,,'_butgthe
.
,
,
statœsrst:
hnggn
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.
_Ires'ponds to Stronger blpw's}.
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Çthan=the—1äterllinéÇ.ëai :
25} FIG?! 4O%Stamcystf
“heating !
î1—:
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Sorgan.zs., ”sacculus contammg
'
Î"Ï=‘ ThC lateral» llIl—Ç',
îo‘tolith Ïand,
;;aaÇ, qe;, ,
’
'
seem also to be of*som€ use: ap., .amrullæ;
.
.
.
'
'
Cells) ;“Éça., anterior semi—circular
,_
both 1n orientation, accord—
canal;
ing to the differentstrengths
°Èaf
Canal ; CP53'POËŒÏÏOÏ semi.
…
mrcular canal (sem1—d1agrammatœ,
of currents on the two s1des
from
of the body, and in balancing. Lee found that when the pectoral and ventral ns
were,
removed, the sh (Opsanus) showed
lack Of
equilibrium so long as the lateral line was left intact.
'
But the balancing of the body seems to'be the main : .: ,
function of "the senscä—organSinthe labyfinth_ of
‘
cyst (Fig. 40), towhich the impressions—are conveÿed d‘irèèftlÿ ' ' _
"
f:
means of the_air-bladder… The Îlatteri$Çexùë
thé
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The stätdcys:$e‘l£ censiëts 6fia: number0f iPhtmb*ä
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