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Scientific Memoirs by
between the venom-duct and the canal of the fang and the more or less erectile
nature of the fang—especially in vipers.1 The "difficulty in making the
viper ( Daboia ) insert its long slender fangs into the tough skin of the cobra'
i s n o t e d . 2 T h e v e n o m m a y i n p a r t b e w a s h e d o u t w i t h t h e b l o o d e s c a p i n g f r o m
the wounded part.3 The snake may have recently shed its venom and have
little more available.4 Snakes are also credited with being able to control the
flow of their venom, expelling a larger quantity when irritated and rendered
furious than in ordinary biting.5
A generally recognised difficulty in interpreting the results of such experi-
ments is the frequent mortality of captive snakes.
In Fayrer's experiments the majority of the snakes
operated upon may have been fresh, but the fact is only noted in regard to one
of the bitten snakes. Mitchell's experiments appear to have been made upon
snakes which had been in confinement for a considerable time.6
The necessity for prolonged observation of the envenomed snake is
strongly insisted upon by Mitchell7 and Claude
Bernard8 on the plea that cold-blooded animals are
very much less rapidly affected by venom than the warm-blooded, and hence
the necessity, in their opinion, for the snake being kept under observation during
a period of several consecutive days.9
It is also desirable that the venom experimented with be of ascertained
activity. This precaution had been very seldom
observed.
In the present series of experiments the above-noted sources of error were
to a considerable, extent avoided or minimized by
the employment of freshly-caught uninjured snakes,
by introducing without loss a measured quantity of the venom by the more
precise mode of hypodermic injection,10 by prolonged observation, and by resort-
ing to numerous control experiments to test the activity of the venom.
1Dr. MITCHELL notes ( loc. cit., p. 25),"I have seen the Rattlesnake strike with great apparent ferocity
a number of times, when I have been unable to discover any fang wound whatsoever." Again, "in some
cases it is quite possible that the relations of the fang and the duct are so disturbed that the venom never
enters the tooth at all." And "It sometimes happens that the blow is given, the fang enters, and from the
quick starting of the animal injured, or from some other interrupting cause, it is withdrawn so soon that the
larger portion of the poison is thrown harmless upon the surface near the wound."
2 FAYRER, loc. cit., p. 92.
3 FONTANA, loc. cit., p. 139.
4 idem, p. 140.
5 idem, p. 139. 6 loc. cit., p. 61.
7 loc. cit., p. 63.
8 "Leçons sur les Effets des Substances Toxigues, etc." 1857, p. 291—quoted by Mitchell, who affords a
very full bibliography of serpent-venom literature.
9 In a fourth of Fayrer's experiments the observations were continued for only one day, and in another
fourth for two days only.
10 FAYRER, loc. cit., p. 75 et seq., records seven cases in which cobra-venom was introduced hypoder-
mically into cobras, but in only two was the observation extended till the sixth day, and in none beyond the
sixth day, and no control observations were made.
Mortality of captive snakes.
Necessity for prolonged observ-
ation.
Using venom of unascertained
activity.
General precautions taken.