A Treatise on Sheep:: The Best Means for their Improvement, General Management, and the Treatment of their Diseases.Blacklock, Ambrose
Science
A Treatise on Sheep:: The Best Means for their Improvement, General Management, and the Treatment of their Diseases.
Blacklock, Ambrose
Sheep
3. The eggs may be voided by the sheep, may fall upon the
herbage, and there remain till they are eaten. Such is the
supposition published by Mr King of Hammersmith, in the
_Quarterly Journal of Agriculture_, No. XXXI. p. 331, in which,
after showing the vast number of eggs which must fall upon the
grass, he says, "We must cease to wonder that so many sheep die
of rot; the miracle is, that every sheep does not die of it."! I
cannot, however, for my part, see a miracle in the matter, for
the simple reason, that the eggs of the entozoa are not capable
of retaining their vitality when absent even for a very short
time from the place of their nativity, and therefore may be eaten
with impunity.
II. Supposing the eggs to have reached the sheep's stomach in a
condition to allow of their being hatched, they, according to
popular voice, find their way into the gall bladder by one of two
routes.
1. Mr King, the gentleman above spoken of, conjectures, in the
same paper, that the fluke, after leaving the egg in the stomach
of the sheep, _makes its way up the gall vessels_. This is, I am
sorry to say, a very idle conjecture, as, from the valvular
nature of the opening of the gall duct into the duodenum, an
entrance from that intestine to the gall bladder is perfectly
impracticable to any of the entozoa.[36]
[36] The notion that rot is occasioned by animalcules getting
into the liver is not confined to this country. Leake, in his
travels in the Morea, alludes to an opinion prevalent there,
that the _vidhéla_ (rot) is caused by the sheep feeding in
marshy places in August and September, when it is imagined that
an insect from the plants finds its way into the biliary
vessels.
2. The eggs are believed by a writer in the _Letters of the Bath
Society of Agriculture_, for 1781, to be taken into the blood
along with the chyle from the small intestines, and to be
arrested in the liver by the secretory ducts. This, it must be
clear to every one, is the most absurd of all the notions; for if
a globule of blood, which we must suppose to be the largest body
capable of being absorbed from the intestine, is only about
1/3000 of an inch in diameter, how can the egg of a fluke worm
pass through the same channel, when Mr King has, by careful
observation, shown it to be 1/300 an inch in its shortest
measurement. Again, allowing that they are taken into the blood,
would they not frequently be hatched there, and would they not
also be found in other quarters besides the liver. But do we ever
find them in the blood? Do we ever see them in other organs?
Certainly not.
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