152
THE,BIOLOGY OF FISHES
Lepidosteus (Ganoids). They
not
really suctorial ;
according to Bashford Dean they belong to the mysterious
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class of pit organe or mucus organs, sense buds in some cases,
.
-from which have arisen the lateral line sense organs, the
mouth in some cases perhaps, certainly the nasal organs and
the ear.
Lateral pores belong to the same class. We
nd them everywhere from the Hag-‘sh to the Eel, and on
all or'any parts of the body ; at rst a few cells or groups of
'
cells simply with a secretory or excretory function, then the
_
cells at the base become sensory 'and
'
a
sense
bud or taste organ develops. From these may
‘
come a light organ, an electric organ,
system
small sense buds ora more concehtrated organ, such as
,;the pineàl gland, perhaps even the eye.g As
reniatks, there isno limit
?
:ff' —,{%
'—
Some have
better '*to
clemental.
'
*
The“re is‘…à mysteri0us{
Which is difcult
'
to understand, and which” later Vertebrates have never
developed, at least not
It may be suggested—that
'
-
the—ÿ—end00rinal organs, thymüs and thyroid and pr0bably
Ÿj
.
the others, were originally of this nature.
Î
;
'The mucus secreted is of a peculiar nature and may
1
even be —poisonoùs, though we know nothing of its effect on
other shes.
The most interesting thing is, that when
'
cohned within the cells or glands it leads tothe production
<
of various forms of radiant energy, 1ike,the-müSÇIe
Similar conditions.
_
are
.
_WhiCh this
…
: thêÏradiant energy may come
from— themetabolismbfthe sh
it may come from the
Of foreign- bodies, which live in the mucus cells,
perhaps
their
and they alone giVe
rise ;to the emanations,fnotathe sh.
The former view has
,
:
been the one
until reCently, and
._
'
—
the phenomena—may be described from‘this point. of view
f
rstofall.,
_
,_
-
-
-
»
.
=
—
radiant- énergyis produced by the
‘
“
sloWf Oxidation of various organic substances, called
.