142
OF. FISHES
great.
When the'sh is out of condition, however, or dies,
the membranes gradually cease to have this control and the -
tissues become permeable (Summer, 1906). In this way we
can understand why shes do not taste salt although they
Ï,
live in salt water, a puzzle to many people. N evertheless,
*
they can take in this and other ingredients when preserved.
) {,
Freshwater shes like the Carp have a much greater
_
îÏ
pressure Within the blood than that externally ; by increasing
'
_ÂÎ J
the amount of salt in the water to 10 grm. pro mille Portier
and Duval were able to obtain equilibrium within and
without; but with still further increase in the salinity the
gill membrane seemed to be _forced and the sh died. As
the pressure of the blood‘also increased, though slightly, in
‘
_
theseexperiments, it would seer_n that a small amount of '
able
through the
_mçmbrane; But :, thlSISby
means certain, and Other
.
—'think “that only
pass through
(Sumner,j
It- is? possibleç_thata
able to
Withdraw water and
its exchanges; The Salmon, for
its osmotic pressure all at once on entering
the Eel, When,transferred from fresh to salt water, does not
'
«osmotic pressure of the latter.
On the whole,
therefore, the Condition of the blood is determined by the
inner metabolism and regulatin—g system.
_
_
,
-
;
'
;
_
Dierent species of Telecstsÿary considerably,gand;even
"
Ï
-
the
species ;may yar'y .at:
*
.
-*à@tdia ”f0;ïe
of the
reproductweorgansAsmd1catedm a previous Chapter, î -
of the— >
blood,W1ththeaccompanymgchanges _. in, the tissues, that = Ç
TheElasmobranchs,Sharks…and- Rays, are
—
tof their ,,relatibnsæwith:
?
_
açlarge;
g_:,_urates_in the
thee_fofmerêis but Â.Î;
:Î
the,— salt ,.w3ter.:
great Ï;,ÎË:Ëj
d1erence 1.i1.1_:g Constitution and soàly.;çtäiiäa_riiig,g and the j: