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604                                               MEDICAL JUKISPRUDENCE

moves along. The ridge in the middle of each scale is dented like a saw ;
hence it is called a saw-scaled viper. The broad belly plates, ^ small scales
on the head and entire shields beneath the tail are the distinguishing points
of this snake.

These poisonous snakes possess two grooved or tubular fangs or poison
teeth, communicating by means of a duct with the racemose glands secret-
ing venom. These glands are the homologues of the parotid glands and
situated below and behind the eyes, one on each side The whole mechanism
is so arranged, that all the venom secreted by the glands is discharged with-
out any leakage at the moment the fangs penetrate the skin. The colubrines
have very short and fine fangs, hence they cannot bite through the clothes ;
while the vipers have long and strong fangs, so that they can easily bite
through the clothes. The colubrines must close the lower jaw before they
can inject the venom, whereas the vipers can do so without closing the
lower jaw.

Characteristics of Snake Venom.-— When fresh, snake venom is a clear,
transparent fluid, but loses 50 to 70 per cent of water and is converted into
a yellowish granular mass which can be powdered when dried under a boll
jar in the sun or over concentrated sulphuric acid. The dried venom retains
its toxic properties for an indefinite period. It dissolves rapidly in water.
Cobra venom loses its poisonous property to a slight extent only, if heated
to 73 °C. for half an hour, but daboia verxom loses it altogether, if treated

Snake venom is not a simple solution of one poisonous substance, but is
a mixture of one or more of the following 7 : — •

1.    A powerful fibrin ferment. — This is separated at 75f'C», because it is
destroyed causing coagulation of the blood,

2.    An anti-fibrin ferment. — This is not important.   It causes permanent
fluidity of the blood after death.

3.   A proteolytic ferment.

4.    Cytolysins. — These   are  present   in   a   greater  proportion   in   the
viperine poison.   They are capable of acting upon the red blood cells, leuco-
cytes, endothelial cells of the vessels, nerve cells, and th© cells of various
other tissues.   Hence in bites "by viperines there is much haemorrhage and

5.    Agglutinin. — This is for the red blood cells,

6.    Neurotoxins. — These attach themselves to all the nerve cells and
especially the cells of the respiratory centre.   Those are the chief consti-
tuents of the colubrine venom.   Hence paralysis, especially of respiration, is
a marked symptom.   These substances vary greatly in different specimens,

7.    A substance, which acts directly on the heart muscle, stimulating it
and increasing its tone.   This is also more marked in the colubrine venom,

Non-Poisonous Snakes. — There are several species of non-poisonous
snakes inhabiting India. Their tails are not markedly compressed, and in
most of the varieties their belly is covered with transverse plates, which,
however, do not extend completely across it, They possess several small
teeth attached to a short maxillary bone, and have BO long and grooved
tangs like the poisonous variety.

Symptoms of Snake Poisoning (Ophitoxaemia)*— These vary according
to the variety of the snake. In the case of a bite from a colubrlna snake,
such as a cobra or krait, the immediate local effects are a bur$yta^0t tingling

MaL G°™\P^CUTMV^e 5P articl? on Snake Ven°™ «ri Anti-vtnomous Sera by
Major George Lamb, I.M.S., m Transactions of the Bom, Hed C0i*gr,» 1000, p, 242,