-
.
THE FOOD QUESTION
‘
315
tion of the plankton is by no…means uniform, which is a
necessary condition for the successful estimate of the
quantities over a large area. The plant organismsourish .
best under certain conditions of light,
chemical composition of the water. They alone have the
‘
power of reconverting the end-products of
,
animal meta—
bolism,carbonie acid and ammoniacompounds,into useful
food for animals. 1 Consequently they are more abundant
in the littoral waters and the currerits of the sea distribute
_
them unevenly, in “streaks ”,;over a wide area. -»Lastly,
it has been found that even the .nest nets do not capture
the smallest- kinds Of
_
plankton (nannoplankton), which may
perhaps. be considered as the basis of allthe rest. And, if
'
we take Pütter’è theory into account, we must go still further
'
backarid estimate the dissolved organic
in the
water, phosphates and carbohydrates, which are not at all
represented in the plankton nets, or the ltrates obtained
by means of a centrifugal pump. -
.
'
:
.
These
_
It'ï may;_gappear to ;——some, therefore,
Ÿ that = Hensen
…the}Wrîongend, :th“àt the rst thing "to do -was"to
=;eXac‘tlybthe dieret forms of plankton life and
.
the limits of accuracy in his
But it has to be
remembered that knowledge on these points Would probably
not—have been obtained but for the necessitÿ of critically
examining every point in the—practical application of the
method.
-
‘
.
"
In one respect, however, it is possible that Hensen’s
‘
conception. might be put to good use. An absolute determi—
'
nation of the plankton may be beyond reach, and even the
relativevalue—that is, comparison of one area or zone with
another—jmay be n1isleading; but if we take the larger
"
,
objects, such as the sh eggs and early larvæ of shes,
a
'
rough measure is obtainable of the sh wealth of.the_ sea——- ‘
-
‘
for : example, in a*restricted region like the Kattegat or
Southern North Sea. ; Here again, however,-the method,
has IO?ïb6 used , With care;
Fish
“Spawn?— uniformly
over
area, nor do they geta‘i—d “of their egg5' all ”at one time, ‘
.
.
THE FOOD QUESTION
‘
315
tion of the plankton is by no…means uniform, which is a
necessary condition for the successful estimate of the
quantities over a large area. The plant organismsourish .
best under certain conditions of light,
chemical composition of the water. They alone have the
‘
power of reconverting the end-products of
,
animal meta—
bolism,carbonie acid and ammoniacompounds,into useful
food for animals. 1 Consequently they are more abundant
in the littoral waters and the currerits of the sea distribute
_
them unevenly, in “streaks ”,;over a wide area. -»Lastly,
it has been found that even the .nest nets do not capture
the smallest- kinds Of
_
plankton (nannoplankton), which may
perhaps. be considered as the basis of allthe rest. And, if
'
we take Pütter’è theory into account, we must go still further
'
backarid estimate the dissolved organic
in the
water, phosphates and carbohydrates, which are not at all
represented in the plankton nets, or the ltrates obtained
by means of a centrifugal pump. -
.
'
:
.
These
_
It'ï may;_gappear to ;——some, therefore,
Ÿ that = Hensen
…the}Wrîongend, :th“àt the rst thing "to do -was"to
=;eXac‘tlybthe dieret forms of plankton life and
.
the limits of accuracy in his
But it has to be
remembered that knowledge on these points Would probably
not—have been obtained but for the necessitÿ of critically
examining every point in the—practical application of the
method.
-
‘
.
"
In one respect, however, it is possible that Hensen’s
‘
conception. might be put to good use. An absolute determi—
'
nation of the plankton may be beyond reach, and even the
relativevalue—that is, comparison of one area or zone with
another—jmay be n1isleading; but if we take the larger
"
,
objects, such as the sh eggs and early larvæ of shes,
a
'
rough measure is obtainable of the sh wealth of.the_ sea——- ‘
-
‘
for : example, in a*restricted region like the Kattegat or
Southern North Sea. ; Here again, however,-the method,
has IO?ïb6 used , With care;
Fish
“Spawn?— uniformly
over
area, nor do they geta‘i—d “of their egg5' all ”at one time, ‘
.