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436                                               MEDICAL [JURISPRUDENCE :

5.    By introduction within the spinal membranes.

6.    By injection into a blood vessel.

7.   By introduction into an open wound.

8.    By introduction into the natural orifices, such, as the rectum, vagina,
urethra, ears, etc.   The dose to act as poison through the rectum is probably
double that required by the mouth.

The Channels of Elimination.  The channels of elimination by which
poisons are excreted from the body are the urine, bile, milk, saliva, mucous
and serous secretions and perspiration.


The action of poisons on the animal system is 

1.    Local.

2.    Remote.

3.    Both, i.e. Combined.

1   Local. The local action of a poison by coming into direct contact

with the part may consist in                             '    r

(a)  Chemical  destruction  by   corrosives,   such   as   strong   acids  and

(b)   Congestion  and inflammation by  irritants,   such  as  weak  acids,
/   '         arsenic, tartar emetic, or cantharides.

(c)  Effects on the nerves of sensation or motion, e.g. tingling of the skin
and tongue by aconite, and dilatation of the pupils by belladonna or



2.    Remote.  Remote action is produced either by shock acting reflexly
through severe pain caused by corrosives, or by poisons being first absorbed
into the system through the blood and then exerting a specific action on
certain organs, and tissues.   Fror instance, cantharides acting on the kidneys
produces nephritis, mix vomica acting on the spinal cord causes tetanic con-
vulsions, opium acting on the brain produces narcosis, and potassium chlorate
acting on the blood converts oxyhsemoglobin into methsemoglobin.

3.    Both, i.e. Combined.  Certain drugs, such as carbolic acid, oxalic
?tcid,' phosphorus, etc. act locally by producing irritation, "and inflammation of
the parts with which they come into contact, and then produce remotely
setious symptoms, after they have been absorbed through circulation.


* j,      -             *

-' -. The causes which nnodify the action of poisons, are four in number 

1.   Quantity.

2.    Form.

3.    Mode of administration.

4.    Condition of the body.

j    L   Quantity. The natural pr^mB^tiw is that a large dose of^a poison
will produce death. more, rapidly fe^cE^^ng severe symptoms >
one but, in some cases, the evil effects are mitigated by vomitipg
a large dose of a poison, such as copper sulphate.   Mbr'eoV<ir,
a poison varies with the quantity1 bf ife dose.   For -instanefef a ^
of arsenic may.;paaoefoce death Jby shock, without
^a; smaller- dose 4han a tetlbal one
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