'
VARIATION —AND DIFFERENTIATION’ '195
of the year,and is apparently dierent in dierent
and localities.
These small differences
be of
importance in
Species constant ihtheir'dierenæs
from one another.
,,
,
,.
,
The movements of
'_
,
chor‘d breaking up intodenite centra otvertebræ,cannotbe
,
,
left out of account as a,:oaœebf
Thechaseoffood
=
is a necessitv of its
the littoral watèts,the larÿaïhas not to workso hagdëfbrf a living
,
as its brethren out Over{deeper waters of incolder climateSz,_
'
In the critical stage; When
_
the Îyoungîshïhas to travel fartherîand faster
a
'
what1tneeds(£fFzstulana,
,V ), so that, the biological
some inuence on the”vatiatiÔns. Ï
,
'
Ihrief, we my Say
the balance
,,
'
and movements of the yoùng sh, embryo, larva or post—,
"
_
larva, whetlîer physical, Chemical or biological, is a potential
:
_
'causef'of variation, With more experiments
‘f
]ohs.’
and
1tw1llmcourse of
,
f
'
'f
‘—
dngwmygdthpntndndnfm
.:
; paentwsamengtbeexemalmuencœ î5£1î‘r
,
f.
,
i; j It is hôWa‘mättëf ofcommoakrowldgeamongtmse
»
who have studied the strùCtùré and development of“ shes '
,
that
“
species
”
are not
6 from one
_
.
but show a merging of the characters in every group that has
_
'
or less well investigated. The following example,
showmg the number of
in various species of
f, ;“ Arnoglossus,Willillustrate what this means
: ;
;
,
35
'361 37
393 4°:
T'
24iGmhmanmn4 —— -—*—'
—
:"+1— ———————————_—— ,
_.
A;
——
,—,—,-, :——…
,'9,>62 539
2-——————
A>latèma_ra-ig—%Ï —Η— —.— :,2x 46
,
:
A";
—_—
"—
—————
,
,'
“
A—'Rüppelii .—r—: —— —— —— — —-———1 62 ' i