308
THE BIOLOGY OF FISHES
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mother—sh and emerge’ With all their structures
formed.
They have no organic connection with the
sh and must obtain their nourishment from the ovar1al
uid, which is rich in dissdlved organic stus.
distance between these and the broken—down ova or tissUe_
cells, on which they are supposed to live, is not very
Lastly, many Teleostean larvæ pass through a difcult
stage when the mouth is being formed (Chap. IV), and
not appear to feed during this period.
_
These examples indicate that Pütter’s theory
be
qùite correct, so far as the young post—larval stages of the
T eleosts are concerned. In the older stages, When
tissues haVe become more dierentiated, it is Open to dOubt
whether any. assimilati0n of food—stus can take place except [
through the digestive
far as experiments haVe;
,
gone, the living membranes-Of thelgills prevent the diffusion
of anything but water
ithàs. to be ôted
.
still few5inçnnmber and
to decide the question;
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Apart from the above possibility it may be
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said in general, that all esh is gràss. [The animals feed
upon one another, but when we go low enough or
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back, the smaller animals are
.b‘ef feeding on
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