’
ADAPTATION
265
\
of the organism to use and adapt, its structures according to
'
the conditions, a great deal of ' the difculty disappears'.
Some of the following examples will perhaps make the
distinction more evident.
,
,
'»
,
'
.
—
,
ADAPTATIONS CONNECTED WITH THE MODE .ÔF,
'
—
'
The mouth of sheS is a grasping organ, the only organ
of the kind they possess, and it —is used for several diererit
purposes and in several dier-eht ways .,‘for the,same purpose.
'
It has to obtain food—, thoùgh all is not food that enters the
mouth, and it has to supply water and 0X‘ygen to the-gilla
_
But its power as a-graspingorgan depends upon the rate of '
swimming and the kind of animals pursued. Fast swimmers
have a large gape, sharp teeth, and a wide gill—opening;
slow swimmers have all sorts of mouths, even very large
ones, but broad and not pointed. Most shes are carnivorous, and in the predatory kind the teeth are not only
'
pointed, they are very numerous and on other bones
as: well
as the jaws, vomer, palatine, tongue, etc., as in: the-Salmon
,'._'.
"
—.
-,
,
*
ÎIt is
the mOuth and-teeth are adapted '
'
to
because'they are used in this
'
or:thatmanher‘, but “a"general.-Comparison of many cases
often reduces the value of
Eor example,
\
it- has beenthought that the loose front :teeth:of the}Anglen
,
Which fold into themouth and are
When the préy
tries to escape, simply by the action of the latter; is an
adaptation of special merit. But if the xed teeth of a Hake
'
cria Conger get hold of anything, there —is not much chance
'
,
Ï.O_f theprey escaping. Tomake the looseteeth an adaptation,
[we—. Should: have to imagine that the prey on entenng
_
_
mouth hâd:rsît of all loosened the teeth, for that is thepecuh- ,
‘
: '_
.We might».in
this Ras
sOme ”fault in ':the'» 'dçäve‘l_ÿpl.<ît
'
and
that the, shdoeS very,
'
=:'jl
'
:
,
=
—.
'
'
'
'
Ingeeral, indéed, the jaWs andteethare
'
elementary condition among the -shes, that is} t901
much
'