_VIPERINE FANGS._
THOUGH the ensuing chapter will be devoted more exclusively to the
_Crotalidæ_ or rattlesnakes, it were well to repeat here that the two
families _Viperidæ_ and _Crotalidæ_ comprise the sub-order of Ophidia
‘VIPERINA,’—those that have the isolated, moveable fangs, the term
_isolated_ having reference to the functional fang only. It may appear
incongruous to present the illustration of a viperine jaw with a whole
cluster of fangs, while affirming that there is the one pair only; but
the pair in use are ‘solitary,’ because the jaw bears no simple teeth,
as in those with fixed or permanently erect fangs.
The first observation of the mobility of the viperine fang and its
peculiar structure is ascribed to Felix Fontana,[99] an eminent
naturalist and Professor of Philosophy at Pisa, in the eighteenth
century. He formed the cabinet of Natural History at Florence, and died
1805, in his 75th year. But the _mobility_ or action of rattlesnake
fangs was known long prior to Fontana, and he probably borrowed the
expression ‘dog-teeth’ from the old Virginia writers who thus called
the fangs. Purchas (1614), quoted in chap. xvi., describes ‘venomous
Serpentes, one ten Spannes long, with great Tuskes, which they hide and
stretch out at pleasure.’[100] And again, in describing ‘foure kinds
of venomous Snakes. The first is greatest, Jararacucu, that is great
Jararaca, and they are ten Spannes long: they have great Tuskes hidden
in the Mouth along their Gummes, and when they bite they stretch them
like a Finger of the Hand; they have their Poyson in their Gummes,
their Teeth crooked, and a Stroake vpon them whereby the Poison
runneth. Others say they have it within the Tooth which is hollow
within. It hath so vehement a Poison that in foure-and-twentie Houres
and lesse it killeth a Man.’[101]
There can be no doubt but that viperine fangs are here described, those
belonging to the South American _Crotalidæ_, under their vernacular
but then their only names. Dr. Ed. Tyson, who dissected the first
rattlesnake that was handed over to science (p. 275), quite understood
the mobility of the fangs, and of the existence of supplementary teeth,
though not fully comprehending the nature of these latter; which ‘I
could not perceive were fastened to any Bone, but to Muscles or Tendons
there. These Fangs were not to be perceived upon first opening the
Mouth, they lying couched under a strong Membrane or Sheath, but so as
did make a large Riseing there on the Outside of the lesser Teeth of
the Maxilla’ (meaning the reserve fangs), ‘but at Pleasure when alive
they could raise them to do Execution with, not unlike as a Lyon or a
Cat does its Claws.’[102]
He found seven reserve fangs on each side; and though they were not, as
he tells us, ‘fastened to any bone,’ the illustration represents them
growing in regular order according to size in the jaw.
In another paper read before the Royal Society in 1726, also anterior
to Fontana, on the ‘Fangs of the Rattlesnake,’ the writer, Captain
Hall, describes the dissection, which was under the direction of Sir
Hans Sloane; and ‘then the Muscles that raise the poisonous Fangs
appear.’ This anatomist also found reserve fangs. ‘Putting by this
Membrane, the fatal Fangs appear, which on first View seemed only one
on each Side, till searching further there appeared four more. The
first and largest is fixed in a Bone;’ four others were loose in the
membrane.[103]
Several of the old authors quoted in the chapter on Rattlesnake History
of the Seventeenth Century were quite aware of the action of the
‘Springing Teeth,’ ‘Master Teeth,’ or ‘Canine Teeth,’ as the fangs were
variously called; and Lawson, 1707, describes ‘the Teeth which poison
are two on each side of the Upper Jaws. These are bent like a Sickle,
and hang loose as if by a Joint.’ Fontana’s observations were possibly
of greater scientific importance, otherwise it is singular that his
equally thoughtful predecessors, from whom he no doubt culled much
important information, should have been overlooked.
In these viperine fangs there is an analogy between the vipers and the
lophius, a fish with moveable teeth; only in the fish, as Owen tells
us, the action is not volitional,—the teeth bend back to admit food,
and then by elastic muscles spring up again to retain it.
The true nature of the reserve fangs was surmised by Mr. John Bartram,
who in 1734 wrote from German Town, in the American colonies, to a
F.R.S., ‘On a Cluster of Small Teeth at the Root of each Fang or Great
Tooth.’[104] He had a rattlesnake, ‘now a Rarity near our Settlements,’
and dissected it, when he ‘found in the Head what has not been observed
before by any that I can remember; _i.e._ a Cluster of Teeth on each
side of the Upper Jaw at the Root of the Great Fangs through which
the Poison is ejected. In the same Case that the two main Teeth were
sheathed in, lay four others at the Root of each Tooth in a Cluster of
the same Shape and Figure as the great ones, and I am apt to think for
the same Use and Purposes, if by an Accident the main Teeth happen to
be broken. May not these be placed to supply a Defect successively, for
the Support of this Creature?’
Mr. Bartram was singularly correct in his diffidently-offered surmises;
nor is it likely that in such a remote district as German Town then
was, he had ready access to foreign publications, or would have claimed
originality had he been cognisant of the work of M. Moyse Charas,
_New Experiments upon Vipers_, translated from the original French
in 1673. Charas, after describing the ‘_Great Teeth_,’ refers to the
‘smaller teeth’ (reserve fangs) ‘that are there in a Nursery, and are,
if we may say so, in expectation to serve instead of the many Teeth,
whether these come to fail of their force, or fall out of themselves.’
The author, to add weight to conclusions evidently originating from
personal investigations, tells us that he had ‘taken Pains to grovel
with a good deal of Patience in the Gums of innumerable Vipers.’
The Italian Redi, even prior to Charas, had also ‘grovelled’ in
the gums of Vipers, and observed the canal or slit in the fang,
‘_si fendono per lo lungo dalla radice alla punta_,’ and that these
canaliculated teeth in the moveable jaws (_ossi mobili_) were for the
conveyance of the venom.[105]
Thus, one hundred years prior to the work of Fontana, the structure of
the viperine jaw was understood and described by several—we may almost
say many—anatomists, to whom let due honour be rendered for their
individual and independent researches; from all of which Fontana had
doubtless benefited.
And so from numerous sources we might go on culling and quoting;
_Philosophical Transactions_ of France, Florence, Germany, and America,
as well as of England, showing us that little by little the scientific
workers examine, compare, correspond, till out of their life’s labours
a fact is established that may be printed and learned in six lines, but
which—as is well worth remembering—often represents the brain and
eyes and time of ages of scientists.
Next to engage attention was the _structure_ of the fang and the
‘involution’ described in the last chapter. A paper on this subject by
Thos. Smith, Esq., F.R.S., was read before the Royal Society in 1818.
Mr. Smith claims to have been the first to observe this involution as
being altogether different from the perforation of the pulp originally
supposed to be the case. He first noticed the slit in a cobra’s fang
(he being in India), and afterwards in a Hydrus (sea snake), and it
led him to further investigations. With a microscope the slit was
perceptible in a rattlesnake fang (which was also observed by the
present writer before reading this account).
One more paper in the _Philosophical Transactions_ on this subject
must be commended to the interested student. It is the one already
quoted (p. 363), ‘On the Succession of Poison Fangs,’ by Charles
Tombes, M.A., vol. clxvi. p. 470, 1876. In this paper is presented the
result of all the most recent investigations, enriched by still deeper
researches, but of too scientific a character to be introduced in this
simple narrative of the progress of ophiology. We may, however, say
that Mr. Tombes finds the character or function of succession differs
in the vipers from that of the venomous colubrines; and this, as the
construction of their fangs and maxillary jaw differs, is what we might
look for.
A few more words descriptive of the external aspect of the _Viperidæ_
may summarize what has already been said of them. Schlegel suggests
that their ‘noxious character is expressed in all their parts.’
With the exception of brilliant colouring, this may be accepted as
a rule. The broad, flat, angular head, rendering the ‘neck’ thin
and conspicuous, has gained for many of them the generic, sometimes
specific name of _Trigonocephalus_. From their deadly qualities,
_Clotho_, _Severa Atrox_, _Lachesis_, and _Atropos_ are among their
names; while _caudalis_ and _brachyura_ describe the short, thin tail
as opposed to the long and tapering tails of most colubrines. The true
vipers—those that have not the nasal fosse—belong particularly to
Africa, the _Crotalidæ_ proper to America, the chief distinction being
that the _Crotalidæ_ have and the _Viperidæ_ have _not_ the ‘pit’ (see
p. 277), of which more in the next chapter. The rigid, lanceolate
scales covering the head are another viperine characteristic; also
thick, heavy bodies, tapering at each end, and rough, carinated scales.
They inhabit for the most part dry, arid deserts and sandy uncultivated
places of the Old World, Africa being their most congenial habitat. The
coloured viper and young one convey a good idea of their general aspect.
Ophiologists do not agree in the arrangement of genera and species,
on account of the forms running so much into each other. Gray gives
nine genera and twenty species; Wallace, three genera and twenty-two
species; and Dumeril, six genera and seventeen species. The Death
adder of Australia (p. 172) is a heterogeneous species. Its aspect
is viperine, yet it has not viperine fangs, and does not therefore
belong to this chapter. Schlegel thinks it ought not to be separated
from the true vipers, but Krefft does not state positively that it is
viviparous, so it is altogether anomalous.
The researches of Dr. Weir Mitchel of Philadelphia have been of great
value to ophiologists. For two whole years he gave the best portion
of his time to the study of rattlesnakes, having a number of them
under constant observation. An exhaustive paper by him was published
in the _Smithsonian Contributions_, Washington, D.C., in 1860, giving
details of experiments with the venom and the treatments adopted. But
of especial interest here are his observations on the fangs and their
volitional action, it having previously been supposed that the mere
opening of the mouth brought the fangs into position, which is not the
case. As the _Crotalus_ can move each side of its mouth independently,
so it can use one or both fangs. ‘When the mouth is opened widely,
it still has perfect control over the fang, raising or depressing it
at will.’ Dr. Mitchel saw that though both fangs were present, both
were not always used. When a viperine snake yawns extensively, as it
so often does, you may sometimes perceive the fangs partially erected
or entirely so, or the ‘vibratile motion’ in them observed by Fayrer.
When the snake is angry, this vibratile action is much like that of
a cat gnashing the teeth; but when only in a yawn, the partial and
unequal erection of one or both fangs has the appearance of being
involuntary. In this I speak from observation. The effect is similar to
that seen about a person’s mouth in trying to suppress a yawn—a sort
of convulsive, nervous twitching. Whatever the cause, you perceive the
fangs moving, but _not_ moving always in accord.
The shedding or replacement of the fangs is, Dr. Mitchel thinks, a
regular process, as in the teeth of some fishes, though not regular
as to time. Sometimes, but not always, they are shed with the casting
of the cuticle. He ‘cannot suppose that the almost mature secondaries
are awaiting an accident;’ which agrees precisely with the opinions
of Dr. Edward Nicholson and other physiologists quoted in the last
chapter: ‘A crop of young teeth’ (or of fangs) ‘work their way into the
intervals of the old teeth, and gradually expel these latter.’ When
lost by accident or by violence, therefore, the process of replacement
is slower, as we can readily conceive, the ‘secondary’ next in turn not
being as yet ready for duty.
Though the American scientific journals devoted to zoology are rich
in ophidian literature, there are few available to English students;
and I regret I am unable to ascertain from across the Atlantic the
latest researches and conclusions regarding this and several other
correlative points. To Professor Martin Duncan I am indebted for the
loan of a volume which forms one of the ‘Bulletins’ of the United
States Geological Surveys, containing a valuable ‘Report’ on the
Crotalus by Dr. Elliot Coues, of the United States army, late surgeon
and naturalist to the United States Northern Boundary Commission, 1878.
It is these frequent Exploring Expeditions of America that have done so
much to enrich science in all its branches; as to them are appointed
efficient geologists, botanists, naturalists, and other scientists, who
send in their ‘Reports’ to Government, to be soon reproduced in the
form of large, handsomely-illustrated volumes. Copies of these (often
consisting of ten to eighteen thick quartos) are presented to the
members of Congress, governors of States, and to many others in office,
also to literary institutions. You may have access to them in almost
every large town in America; and there is no information connected
with the history and natural productions of the nation (including
the aborigines) that cannot be found in their pages. And as our
Transatlantic cousins are always exploring some new territory, and have
still untold square miles of mountain and valley to explore, their
scientific ‘Reports’ in huge quarto tomes can be more easily imagined
than counted.
This little digression from the viperine fangs is by way of introducing
Dr. Elliot Coues. The volume in question was not forthcoming at the
British Museum, therefore I ventured to trouble Professor Duncan with
some inquiries, which were kindly responded to by the sight of the work
itself.
There is in Dr. Coues’ paper a good deal of what has been here already
described; but there is also so much that is of additional interest,
that for the benefit of those students who are not within reach of the
British Museum (where, no doubt, the fast arriving quartos will get
catalogued in due time), I will transcribe from the text some of the
passages as relating to viperine fangs generally.
‘The active instruments are a pair of fangs.’ ... They are ‘somewhat
conical and scythe shaped, with an extremely fine point; the
convexity looks forward, the front downward and backward’ (referring
to the slight double curve in the Crotalus fang as shown in the
illustration, p. 360). They are hollow by folding, ‘till they meet,
converting an exterior surface first into a groove, finally into a
tube.’ ... The fang is ‘moveable, and was formerly supposed to be
hinged in its socket. But it is firmly socketed, and the maxillary
itself moves, which rocks to and fro by a singular contrivance. The
maxillary is a small, stout, triangular bone, moveably articulated
above with a smaller bone, the lachrymal, which is itself hinged upon
the frontal.... This forward impulse of the palatal and pterygoid
is communicated to the maxillary, against which they abut, causing
the latter to rotate upon the lachrymal. In this rocking forward of
the maxillary, the socket of the fang, and with it the tooth itself,
rotates in such a manner that the apex of the tooth describes the arc
of a circle, and finally points downward instead of backward. This
protrusion of the fang is not an automatic motion, consequent upon the
mere opening of the mouth, as formerly supposed, but a volitional act,
as the reverse motion, viz. the folding back of the fang, also is;
so that in simply feeding the fangs are not erected.’ (But I think I
may affirm positively that sometimes the vipers do use their fangs in
feeding. When they open their mouths—or rather the jaws alternately
very wide—I have seen first one and then the other fang occasionally
engaged in the food and again disengaged unsheathed. On other occasions
the fangs have been folded. In some large African vipers, the ‘River
Jack’ and others that were in the Society’s Gardens a few years ago, I
was able to observe this easily.)
The fang is folded back ‘with an action comparable to the shutting of
the blade of a pocket-knife; ... one set of muscles prepares the fangs
for action, the other set stows them away when not wanted.... The
fangs are further protected by a contrivance for sheathing them, like
a sword in its scabbard. A fold of mucous membrane envelops the tooth
like a hood.... The erection causes the sheath to slip, like the finger
of a glove, and gather in folds round its base.... It can be examined
without dissection.’ (And with the naked eye in a large viper, even
during life, you may sometimes perceive this sheath or hood half off.)
‘Each developing fang is enclosed in a separate capsule,’ says Dr.
Mitchel, which is just what I thought I saw in ‘grovelling’ up the poor
Bushmaster’s reserve fangs. There was an immense deal of loose skin to
remove, which under skilful manipulation would doubtless have presented
the form of sheaths of various sizes. At last I came to a great deep
cavity as big as a bean or a hazel nut, and this I left neat and
uninjured for some one else to explore. It might have been the poison
gland! The young Jararaca’s mouth is too small to reveal its mysteries.
But now we come to the most amazing of all the wondrous detail of
this living hypodermic syringe. Those who have seen a viper or a
rattlesnake strike its prey, are cognisant of the lightning-like
rapidity of the action. So swift is it that often a spectator is not
sure whether the snake touched the victim or not. A flicker, a flash,
and the bite has been given. Dr. Mitchel, describing the singular
inactivity of rattlesnakes in confinement, points out the striking
contrast between this repose and the perilous rapidity of their
stroke. Now let us look at the amount of business transacted in that
flash of time. Says Dr. Elliot Coues: ‘The train of action is first
reaching the object; secondly, the blow; thirdly, the penetration;
fourthly, the injection; and fifthly, the enlargement of the wound
(the latter by dragging upon it the whole weight of the body by the
contraction of certain muscles, which cause the fangs to be buried
deeper and thus enlarge the puncture); and all these five actions
accomplished in that instantaneous stroke!’ This is what Fayrer means
when explaining that ‘the real bite is when the snake seizes, retains
its hold, and thoroughly imbeds its fangs.’ ‘Sometimes the lower teeth
and the palatine become entangled (and sometimes a fang is left in the
wound).... The force of ejection may be seen when a serpent striking
violently misses its aim, and the stream has been seen to spirt five
or six feet. A blow given in anger is always accompanied by the spirt
of venom, even if the fangs fail to engage.’ ... Another curious piece
of mechanism, and one not previously described that I am aware of, is
a provision for the fangs when they fail to bite. ‘A serpent always
snaps his jaws together, and thoroughly _closes them_ when he strikes;
therefore, if the fangs failed to engage, they would penetrate the
lower jaw. But there is a certain movement among the loose bones of the
skull (perhaps not yet thoroughly made out), the result of which is
to spread the points of the fangs apart, so that they clear the inner
sides of the under jaw, instead of injuring them.’ Coues here describes
rattlesnakes particularly, but no doubt the same extends throughout the
viperines.... ‘In a large snake the entire gland may be an inch long
and one-fourth as wide, having the capacity of ten or fifteen drops
of fluid. There is no special reservoir for the venom other than the
central cavity of the gland. Formerly there was thought to be such a
storehouse; but when the tooth is folded back, certain muscles press
or compress the canal to prevent a wasteful flow: in other words, the
communication is shut off!’
In this wonderful exhibition of the ivory hypodermic syringe there
has not, I trust, been so much repetition as to render the subject
tedious. Presented in such graphic language and from such a source, it
must attract almost every intelligent reader, while the viperine fang
is absolutely acting before his eyes. On this subject, then, no more
need be said; though on the Crotalus family generally some interesting
matter still remains to be told.
[Illustration]