.
]
'
=
“162
THE BIOLOGY- OF FISHES
‘
embedded in the cartilage and bone on the side of the skull. -
The Whole is lled With a uid, endolymph, and surrounded
by a similar uid, the perilymph. Disturbances in the
’
external medium set up waves in the
Which beat
Ï_
upon the numerous groups of sense—cells and thus convey
impressions of the strength and direction of external
: >
to
the central organ.
In the Elasmobranchs the
Î
lymphatic duct (de and se) is open to the ‘exterior; but in ÉË‘_»}
the Teleosts the organ is cômpletely enclosed. In some
forms a continuation from the air-bladder is indirectlÿ
connected With the endolymph, as Will be described later.
,
5.'EYES OF FISHES
.
Asvvi1h
and hearing organs, an
_Lhe-Ïreceptionfbf light stimuli is only present
’
Ï
—
"
jf
m0ve;.
may say—thatit has arisenf—
Ÿ
—
in consequence of the movement, and
m
?
the latter
is probably a factor in 1ts
'
,
i
1
_
C5
formation.
it is
_
,—
?
@ ;;
the regulation_of the
—
'
'
'
The eyes Of _shes have also
from
-—
1
J—_
-
,
have sunk
FIG.4I.—-—bye of Trent
'
.
.—
—
::
.
'
a direct
t.;
r01d.Çoat;cg—,Chorold
__
;
€
Ï
::.16113 is Of.
: Bll(Fmaxdszandsthus … adaptable 3;
,
_,
_
_
_
ndHaswell)tewswnat varymgî distances How
this regulati0n» is …made, is, Still not
î
can
be moved backwards‘
;
and: from the retina, the image
_
“latter cannotgbe'
or distinct
to
1n
cannot be'foeuSsed onÿanëobject
=
-
atthe ”same
;_=—_Î Imperfect ÿarid =WÇ=fse_èÿzthat
shes