1354
ELEMENTS OF MATERIA MEDICA.
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The animals usually deposit their ova (in their own native waters) in holes ° r , ‘ e ni
places on the shore, usually from May to 11 art >Fig. 245. of September. When first expelled, tj*® J e a
somewhat cylindrical in their form, and ||| )er esbrownish appearance. The frothy layer a ^ 3very slightly; but after lying in the w!lt , er c0 iiie squarter of an hour, the outer surface “f j e 0 tsomewhat hardened, forming a kind of p e .''frothyfine skin. After some days a portion of this ^
covering is converted into a spongy tissue (1 t | |( >_ t _i _• _ oi ,,
coat of the cocoon ), covering the caps
the
Diagram illustrative of the internalanatomy of S. medicinulis.
b, Last ganglion.
Between these will he ob-served the chain of gangliaof whicli they form portions.
c, Lateral or branchial vessels.
d, Folded mucous glands;
is connected by a duct to anair vesicle.
e, Penis, the rounded enlarged
base of which is supposed tocontain the prostate gland.
/, Vesiculte seminales.
h, Testicles.
of the diseases of leeches,as common to this animal:
ova ( cocoon ) wholly or partially. In this st ^; [U ila''cocoon has a brownish, fibrous appearance,; an dto fine sponge, and varies somewhat in its siweight; its longest diameter being fr° ,n j jtstwelve lines, its shortest from five to eight,weight from twenty-four to twenty-eight t,
(See figures of the cocoon in Dr. J. R.d° nFurth. Observ. on the Med. Leech , 1825).
The ova or germs, which have a lenticular ^enlarge, and evince vital movements ; a "j tu bCisoon we perceive on each a funnel-shape ^i,extending from their surface inwards, aimappears to absorb the albumen of the cocoon- ^ovum goes on enlarging, and becomes s<» , |, e -elongatcd, and subsequently the young * ee y fijegins to be developed on the exterior par g p U tovum, the aperture of the funnel being 1 ^ e( ),
where the mouth of the young animal is 0 t |]t!
The abdominal surface is the first, the “° r5 ‘ 0l u>!flast, to become developed. When the : ^yleeches have attained a considerable siZ epierce their cocoon.
Diseases of Leeches. — The na ^jjyduration of the life of leeches is not ^ egSdetermined; but judging from the slo' eof their growth, and the length 0 e j,full-grown leeches have been P r £ s a rcwe may necessarily infer that tn . . ^long-lived animals. Dr. Johnson c;l p
that in their native waters, if tn J 0 te a ch always meet with an abundant sU D "aU-food, they may live at least twenty ) gg>But they are subject to several dis ^ ;1some of which are epidemic, an jyvery destructive kind. Although theof the pathology of this animal nd e ' el *siderable interest in a commercial a ^. ca ]iyscientific point of view, yet no P ra . e( Jid,useful results have hitherto been arrlin regard to the prevention and tr?
Dr. J. R. Johnson mentions three di^ g {
fife h 1 a
It destroys
1 st. An ulcer, seated in various P‘
the body, but more generally affecting the side. It destroys tJJ ..few days. 2dly. A rigidity and narrowing of one part, whils ^ Aportion is studded with • tumors of putrid coagulated blood. ^ j, a rd’flaccid appearance of the whole body, except the lips, which a - u i a rl/swollen, purple, and frequently bloody. These diseases are p ar