,
THE— DEÿELOPMENT
FISHES
81
nerveelement. This is,:the condition found in the Elasnio—
branchs—but only in the caudäl- region, Which emphasises
the fact that the segmentation of the *Vertebral column is
eected by the muscular action. _The same coÏi1dition is
found in
of
(Fig. 17) as Well as
soi‘e other important case‘s”ä=f@ be
mentioned later. It is possible that
of the
vertebræ, especially the caudal, in the
BlennieS
and other elongated Telecéts, has beenbroughtaboutmthe _;
same way.
But in the Specialised Teleosts(Percmds,Scom— -
_
Ïho‘tôchofd
Ï. “Cellular
structure? of
in. & Clupeid .: (From
z. 3 Precaudal
°Euryéôñüs; ”*
VèÏtäa‘b‘ræ of
'
”4…
Càudalœrœbfæof ÀmiaΑ. ri
Zitrelï.) - '
"
bfoids, etc.) the notochordal substance Ïhas_ besoins fnore
concentrated and multicellular.
ï
.
‘
For a long time after the young Teleost is hatched, the
notôchordal tube is straight and its walls become slightly
ossied in the same way as the small bones. Then the move—
mentsÈof the muscles lead to its__:b,reaking up into,segmenŒ—äj
of centra, each between
of muscles.
OssiC‘atio
'
,
.
ceases in the partsbetween the cent—ra where they are Working
_
on each othef;_-and thus the Whole’aXiS cernes-to ‘Âhaye the _Ï
*
appearance of a “long series‘of small
'
clearly Seen in any poStlàrVal
Thenumber : of
‘
these cylinders ing any
is not determ1nedùiïtilïthê
i,
little sh has
THE— DEÿELOPMENT
FISHES
81
nerveelement. This is,:the condition found in the Elasnio—
branchs—but only in the caudäl- region, Which emphasises
the fact that the segmentation of the *Vertebral column is
eected by the muscular action. _The same coÏi1dition is
found in
of
(Fig. 17) as Well as
soi‘e other important case‘s”ä=f@ be
mentioned later. It is possible that
of the
vertebræ, especially the caudal, in the
BlennieS
and other elongated Telecéts, has beenbroughtaboutmthe _;
same way.
But in the Specialised Teleosts(Percmds,Scom— -
_
Ïho‘tôchofd
Ï. “Cellular
structure? of
in. & Clupeid .: (From
z. 3 Precaudal
°Euryéôñüs; ”*
VèÏtäa‘b‘ræ of
'
”4…
Càudalœrœbfæof ÀmiaΑ. ri
Zitrelï.) - '
"
bfoids, etc.) the notochordal substance Ïhas_ besoins fnore
concentrated and multicellular.
ï
.
‘
For a long time after the young Teleost is hatched, the
notôchordal tube is straight and its walls become slightly
ossied in the same way as the small bones. Then the move—
mentsÈof the muscles lead to its__:b,reaking up into,segmenŒ—äj
of centra, each between
of muscles.
OssiC‘atio
'
,
.
ceases in the partsbetween the cent—ra where they are Working
_
on each othef;_-and thus the Whole’aXiS cernes-to ‘Âhaye the _Ï
*
appearance of a “long series‘of small
'
clearly Seen in any poStlàrVal
Thenumber : of
‘
these cylinders ing any
is not determ1nedùiïtilïthê
i,
little sh has