ECONOMY OF THE BODY—I
133
the more crystalloi_d substances; Other uses Will be apparent
from the context.
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7
,
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_
;
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In shes the blood Only amounts to about
cent. of
the Weight of the body, but that doés’n0tÇ-indùd6the lymph;
In addition to the red corpusdes and’leucocytes;the}blocf>d
contains small blood plates and
br
The
latter is of very great imp0rtance alSo,— for it carriesra'quantity ’_
of albuminoids and various inorganic salts, of calciumgfetc., as
'
well as small quantitiesof other
The dièer‘1t
albuminoidsare special or specic, so that theblood of_the
Eel, f0r example, is a poison to the rat and many Other
animals.
In this Way blood relationships have been eXperimentallyrdeternned.
'
Inthe ‘larval stages of the Teleosts, probably also in the
'embryonic
the lymph is of very great
'
importance, not only in the respiration, but also in the
'
formation of the _skeleton.
Above the head there is often
"
a large lymph—sac, indicating that the bones of the _skull are
.
not
being fOrmed without some friction and diiwlty;
,
Sometimes this Sac eXtends Well back over thepectoral
,.
and thefunction of the
‘
'
W€
head-and trunk of thé
ÂétcL) Were formed by
cf ”suchaiyiph organ—__:ÇInamany forms also the“slçin seems
to break away at many places from
"
and lymphoid tissue comes to ll theŸspaces, asin the Soles—,
_
Toad-shes, Pediculates, and Eels. The Eels especially
have an abundance of lymphoid tissue and even a lymph
,
heart in the tail.
As in the formation of the ventricle, it
is probable that some resistance to the circulation here has
led to the accumulation of muscle cells (mesoderm) which
the leucocyteshave arranged into the shape Of a tube. When
—
the lymph-collects there from the free spaces of the body,_
the heart propels it into the caudal vein, and it thus retu‘rns,
to the blOod circulation.
Many shes also hàve’ma‘sSés off;
_
lymphoid tissue in various parts of the body, -for
bn the. heart of the S_turgeon, in the digestive tract and-round
the kidneys of Protopterus, etc. We
Whether
_