64
_
-
THE BIOLOGY OF FISHES
either rolling on the ground, or among the vegetation,
or in nests ; most of the marine forms have_pelagic, oating
eggs, but many also x their eggsto the bottom, Herring,
Blennies, etc.
The constitutional element is clearly that
the eggs are heavier or lighter than water. And to emphasise
this we nd that the Gouramies, which live in fresh water,
have eggs that are lighter even than fresh water and oat to
the top.
-
The size of the egg varies a great deal.
Most of the
pelagic eggs are about 1 mm. in diameter, but some are
smaller, while those of _Halibuts may be 6 mm. or: more.
The demersäl eggs, those that stick fast to the bottom, are
in general larger than the average pelagic eggs, but the chief
_charaetéÿistics are the greater thickness of the shell or chorion
—
and—the larger amount ”of
The eggs of the
freshwate’r
are
much;
Thus, the
Bitterling,
about 470. mm.
of 3 mm., aridsome of the si1uroids have
eggs Of 17—18 mm.- The, largest
{;ïÎËE1ŒmeŒHChS> Sharks and Rays, WhiCh are; laid in iaahard» .. ‘
shell
-
«…:
.
,
.
l
.
—
_
f
.
,_The number. of eggs also varies in a .remarkable manner.
Forms with pelagic eggs usually have an extremely large
number.z Fulton estimated that a Ling contained from
t‘o: 60,ooo,ooo eggs, and Day gives no less than
160,ooo,ooo for a large specimen, [The God
content
aboùt 8,ooo,_oOo to
Until r€Cehtly Ï
_
these Were
Schmidt
—
*
_
has found thattheSun—sh has about ' 300 million eggs in its
usually have
Only—ê fèWäÏ—hundreds,ethe:viviparès shes still: fewen :But
-,——i t iS,Ïastonishing—
number— theyï can:
small
,
Blennyâis.zrecorded .ti0 havè…had
=
'
»
:Y9Héä. initsç Q:VäIY at ;.0î1© tileL,—{though .theùsualÏ: number:
7‘
less ,
,_
_
_
;
fdfê…}©ï5 fêg—igS-rhas—- aïconsiderable
;to
_
-
THE BIOLOGY OF FISHES
either rolling on the ground, or among the vegetation,
or in nests ; most of the marine forms have_pelagic, oating
eggs, but many also x their eggsto the bottom, Herring,
Blennies, etc.
The constitutional element is clearly that
the eggs are heavier or lighter than water. And to emphasise
this we nd that the Gouramies, which live in fresh water,
have eggs that are lighter even than fresh water and oat to
the top.
-
The size of the egg varies a great deal.
Most of the
pelagic eggs are about 1 mm. in diameter, but some are
smaller, while those of _Halibuts may be 6 mm. or: more.
The demersäl eggs, those that stick fast to the bottom, are
in general larger than the average pelagic eggs, but the chief
_charaetéÿistics are the greater thickness of the shell or chorion
—
and—the larger amount ”of
The eggs of the
freshwate’r
are
much;
Thus, the
Bitterling,
about 470. mm.
of 3 mm., aridsome of the si1uroids have
eggs Of 17—18 mm.- The, largest
{;ïÎËE1ŒmeŒHChS> Sharks and Rays, WhiCh are; laid in iaahard» .. ‘
shell
-
«…:
.
,
.
l
.
—
_
f
.
,_The number. of eggs also varies in a .remarkable manner.
Forms with pelagic eggs usually have an extremely large
number.z Fulton estimated that a Ling contained from
t‘o: 60,ooo,ooo eggs, and Day gives no less than
160,ooo,ooo for a large specimen, [The God
content
aboùt 8,ooo,_oOo to
Until r€Cehtly Ï
_
these Were
Schmidt
—
*
_
has found thattheSun—sh has about ' 300 million eggs in its
usually have
Only—ê fèWäÏ—hundreds,ethe:viviparès shes still: fewen :But
-,——i t iS,Ïastonishing—
number— theyï can:
small
,
Blennyâis.zrecorded .ti0 havè…had
=
'
»
:Y9Héä. initsç Q:VäIY at ;.0î1© tileL,—{though .theùsualÏ: number:
7‘
less ,
,_
_
_
;
fdfê…}©ï5 fêg—igS-rhas—- aïconsiderable
;to