_BREATHING AND HISSING OF SNAKES._
FOLLOWING on the subject of the last chapter comes that of respiration;
and in connection with breathing is the ‘voice,’ so far as this class
of animals can be said to possess a voice.
As already seen in the description of the glottis, serpents do not
breathe in the ordinary way, with short and regular inspirations, but
when they do respire, they take in a supply of air to last them for
some time. Their lungs, instead of occupying one particular portion of
the body corresponding with the chest of the higher animals, are less
developed. One lung—or what Professor Owen calls the long pulmonary
bag—of snakes extends along more than half of their body; in some
species nearly to the anus. Only one lung is normal, the other is
rudimentary. The circulation is so arranged that on each contraction
of the heart only a part of the blood is exposed to the influence of
the air and becomes oxygenated, the rest returning to the parts without
having undergone the action of respiration at all. The blood is, in
consequence, poor in red corpuscles, its circulation is comparatively
languid, the reptile becomes easily torpid, and its temperature is
influenced by the surrounding atmosphere more than by the vigour of its
own functions. This is why, when not excited to activity by external
warmth, reptiles can pass a long time without food. Having no fixed
temperature to maintain, one important source of demand for food is
withdrawn.
The air enters their lungs chiefly in a direct course from the
nostrils, only by the mouth when open. If you observe the flatness of
the head, and the very short space that can exist between the nose and
the mouth of snakes, you will readily trace the communication between
the entrance to the trachea and the outer air through the nostrils
when the glottis is not closed. Professor Owen, in his _Anatomy of
the Vertebrates_, vol. i. p. 528, describes this process fully. In
the foregoing description I have borrowed from him, as well as from
Dr. Carpenter, Todd, and others; but as there is nothing like ‘seeing
for oneself,’ I would persuade my readers to watch a snake for a few
minutes. An inspiration at intervals will be easily discerned by the
expansion of the body. You will also perceive partial or slighter
breathings, and the trunk dilating and expanding gently through a sort
of internal respiration which is going on; every now and then comes the
deeper, fuller breath.
You may perceive that sometimes one short portion of the body expands,
as if the lung in that part only were at work. This is more easily seen
in the larger snakes. I have watched these for a quarter of an hour or
more at a time, during which period only a comparatively short portion
of the body showed any signs of breathing. Schlegel, who carefully
studied this action, observed sometimes as many as thirty such partial
dilatations of the trunk and lung between two full inspirations.
In the large reticulated python I once saw that about two feet of the
body, viz. four to six feet from the head, dilated with occasional and
irregular inspirations, and no other part. By and by slight indications
of breathing were observable much lower down, many feet apart from
the previous action, while during the whole time I was watching I saw
not one full and entire inflation of the lungs. This was on a rather
chilly September afternoon, and the python had partaken of a couple of
ducks for dinner the previous day, and it was a time when inactivity is
usual. In a rattlesnake, on the same day, similar partial and irregular
respirations were observable, this serpent having caused four rats to
disappear at his last night’s supper.
Sometimes you can discern no indication whatever of breathing for a
very long time. When the reptiles are not in health, when they are
about to cast their skin, or when in a half-torpid condition, you may
observe this.
When a snake yawns—a long and leisurely proceeding—the lungs are
doubtless greatly refreshed; otherwise these reptiles do not rest with
their mouths open, and the only possible access of outer air by the
lips being through the chink appropriated to the service of the tongue
(and which is as exactly opposite the opening of the tongue-sheath as
the nostrils are opposite to the glottis), they must breathe almost
entirely through the nose, _except when yawning_.
From the elongated form of the pulmonary bag, and the large volume
of air which it contains, we can understand not only how a temporary
suspension of respiration can be supported, but we comprehend how it is
that these reptiles can remain under water for long periods, as they
often do,—not because they breathe _in_ the water, but because they
can for a while do without breathing.
Snakes have been seen to remain perfectly quiet at the bottom of a
clear stream for half an hour or more. Sometimes in this totally
quiescent state one has been supposed to be dead, until, on a stone
being thrown, it has darted away like a fish. None of the aquatic birds
or the cetaceous mammalia can remain so long under water without coming
to the surface to breathe as serpents can.
At the Zoological Gardens they remain for hours at a time in their
tanks. Often you will see a head peeping out—which, unfortunately, is
all we _can_ see—while the bath is being enjoyed, but as often the
head is also immersed, though, of course, for a shorter interval, the
snake lifting it to breathe occasionally.
We can imagine also the great assistance in swimming which this long
air-receptacle must be, these reptiles deriving from it the same
advantage, says Professor Owen, ‘as an eel from its swim-bladder.’ In
chap. XII. is described the almost swimming motion of the more active
snakes when gliding through long grass, or effecting progress over
a very smooth surface. In the water the action is similar—that is,
the progression is by lateral undulations, the tail being the chief
propelling power. Whether through the resisting medium of water, or
beating the air, so to speak, when skimming over smooth or unresisting
surfaces, this swimming motion is ever easy and graceful. In the
chapter on Tails, we shall see what an important agent in progression
is this limb, whether by pressure, as in the burrowing snakes, or by
its oar-like or paddle-like use in rapid motion.
To recapitulate the above in a few words—first, respiration warms the
blood; snakes are cold-blooded because only a portion of the blood
passes through the lungs to become oxygenated, and in proportion to the
diminution of the quantity of blood transmitted to the lungs, so does
respiration become weaker; therefore reptiles are less dependent on
breathing.
Regarding the ‘voice’ of serpents, so surprising are the qualities
attributed to it, that one would imagine the existence of varieties of
snakes of widely differing organizations, if we were to believe all we
read of the sounds they produce. ‘Hissing loudly,’ or ‘whistling,’ is
the rule. No ordinary writer or traveller who says a word about a snake
ever heard it hiss anything but ‘loudly,’ a statement traceable to
the same sentiment which causes persons to talk of the ‘horrid forked
tongue.’ A benevolently-disposed snake who would warn you away with
that terrible tongue would also strengthen his argument by a prolonged
hiss, and the louder the better.
But let us turn to the hard, cold, unpoetical, unimaginative language
of science, and see what a snake can really do in the vocal expression
of its feelings.
Says Dr. Carpenter: ‘In all air-breathing vertebrata the production
of sound depends upon the passage of air through a certain portion
of the respiratory tube, which is so constructed as to set the air
in vibration. In reptiles and mammals it is at the point where the
windpipe opens into the front of the pharynx, that this vibrating
apparatus is situated. Few of the animals of the former class, however,
can produce any other sound than a _hiss_, occasioned by the passage of
air through the narrow chink by which the trachea communicates with the
pharynx; but this sound, owing to the great capacity of their lungs, is
often very much prolonged’ (_Animal Physiology_),—prolonged, but not
powerful, be it observed.
Says Professor Owen: ‘The true “_chordæ vocales_” are absent in
serpents, and the voice is reduced to a hissing sound, produced by the
action of the expired air upon the margins of the glottis’ (_Anatomy of
the Vertebrates_).
Speaking of the escape of air from the lungs, Dumeril says: ‘Lorsqu’il
est passé plus vivement il laisse entendre une sorte de vibration, qui
le plus souvent, ne consiste que dans le bruit d’un soufflement.’[40]
Sometimes, according to the position of a snake, or when the passage is
well open and uninterrupted, the hiss partakes somewhat of a whistling
sound, like the blowing through a quill. I observed this particularly
in a ‘tree boa’ (_Epicratis cenchris_), which hissed at me angrily one
day because I took the liberty of touching it when the keeper opened
its cage to arrange its blanket. The ‘hiss,’ not loud, or by any means
musical, differed from the ordinary blowing only as a current of
air passing through a round tube would differ from the same current
passing through a narrow slit. A true ‘hiss,’ such as we produce
with closed teeth in prolonging the sound of _s_, a serpent can never
express. The nearest approach to it in the human voice is when the
tongue is in the position as if we are about to say _ye_ or _he_, and
then prolong the breath; that is to say, breathe out while the tongue
is so placed before the word is uttered.
Naturally the larger the snake the stronger the ‘hiss;’ the more rapid
the expiration, the more powerful will be the volume of air with its
attendant _soufflement_.
The sound and action, as well as degree, are easily seen in the ‘puff
adder’ (_Clotho_, or _Vipera arietans_). When angry or alarmed, it
draws in a full breath, and its body swells perceptibly; then you hear
the escaping air like a prolonged sigh or blowing till the lungs are
empty. This process is repeated as long as the provocation lasts.
These alternate inspirations and expirations, with their accompanying
movements, the swelling and then diminishing of the trunk and the
regular _soufflants_, are so precisely like those of a pair of bellows,
that excepting in shape, we require no more complete comparison. The
_degree_ or strength of hiss is in this reptile very perceptible. When
recently imported and easily excited, its violent ‘puffing’ corresponds
with a very large pair of bellows; but in time it grows less alarmed
at the appearance of the human beings who unceremoniously stare at it;
and at length the puffing is very slight, ceasing altogether after
the snake becomes accustomed to its surroundings. But if molested and
alarmed, you then see the full play of the lungs, and the whole body
alternately expanding and contracting as before.
We may almost compare this pulmonary action to the panting or full
breathings of ourselves under alarm or agitation. Only, in comparison
as the lung of snakes is elongated, and there is so much of it to fill
with air, so is the sound prolonged, and the breathing a slower process.
There is another viper, the small Cape adder (_Vipera atropos_), a most
deadly little reptile, in which a similar sound to that of the ‘puff
adder’ may be heard. When this creature is disturbed, it draws in a
long breath which expands its whole body in the same manner, and then
in expelling the air, a long sort of wheeze or blowing is audible.
Even in drawing the breath in, a slight sound is heard (as it also is
in our native viper and some others); but instead of the prolonged
hiss by which most snakes display their agitation, this little adder
expresses itself in long successive blowings, like its larger relative
_arietans_, only a little less regularly. In the present instance, I
saw the lung inflated with an agitated undulating motion, as if the
fluid air were entering in little waves. I do not state positively that
this is invariably the case from having witnessed it in one specimen.
This might be the normal process, or this viper’s lungs and health may
have been impaired. I am thus precise because it is unsafe to establish
as an invariable fact in natural history what may have been seen only
occasionally, a habit which has so often led to the promulgation of
erroneous impressions.
The prolonged sound of the hiss in snakes is due to the size of the
lung, they having a large supply of air to draw upon. Some serpents
expand their bodies under excitement without any perceptible hiss:
the cobra both hisses and expands, so do some others; but all these
movements are, no doubt, connected with respiration in some way, just
as in human beings, sighing, sobbing, panting, etc., in which the
ribs take part, are only modifications of the ordinary movements of
respiration, and chiefly emotional.
Very similar also to the manner of the puff adder is that of _Vipera
rhinosceros_, one of the largest African poisonous serpents, known as
the ‘River Jack,’ being fond of water. One of these was in the London
collection for several years, and I observed that whenever disturbed,
its body swelled considerably, while the ‘hissing,’ or expulsion of
breath, alternated with this expansion.
Snakes, like other animals, probably differ in temper or in
nervousness; for while some are noted hissers, others hiss only on
great provocation, and others, again, not at all. One remarkable
example of a non-hissing snake, though from no amiability of temper,
is the little carpet viper of India (_Echis carinata_). Unless you
were positively assured by learned authorities that this exceedingly
irritable little viper never hisses, you would scarcely believe your
ears, so sibilant is the sound it causes by rustling its scales
together.
Sir Joseph Fayrer, in the _Thanatophidia_, describes this as a very
fierce and aggressive little viper, always ready to attack and be on
the defensive. It throws itself into a double coil, and its agitated
motion causes the rough, carinated scales to rub against each other,
and make a sound like hissing, but ‘_it does not hiss_.’
This rustling is very much like the sound of the crotalus rattle, and
the dry scales must be raised in a sort of way, or ruffled, as an
alarmed hen ruffles her feathers. ‘The outer scales are prominent,
and at a different angle to the rest,’ says Fayrer. It generally lies
coiled in a compact form, often like a ‘w,’ as may be seen in the
frontispiece, with its head in the centre, but always towards the point
of supposed danger, which in a cage is facing the spectator.
Curious and wonderful is the agitation into which this carpet snake
throws itself when disturbed, every inch of it, excepting the head, in
motion. The head retains its fixed position, the eyes intently keeping
guard, while the body moves in every conceivable curve, like wheels
within wheels, yet retaining the same outline, or occupying the same
place and space, though every muscle must be in activity.
One can liken this behaviour only to what is seen in the blending
of liquids of different densities. As you look down into a glass
containing one fluid while drop after drop of another is falling, you
perceive fresh currents and curves in every direction. Watching one
of these, it has changed places with another, you lose trace of it,
each drop is lost in the commingling of the whole. So it is with this
wonderful little echis. It is almost impossible to follow with the eye
any one portion or coil of its moving length; but each inch changes
places and mingles with the rest, like blending fluids.
Speaking of an American snake (_Pituophis melanoleucus_), in which a
similar excitement is observable, Mr. Samuel Lockwood[41] likens it
to a ‘mystic wheel.’ ‘The movement consists of numberless units of
individual activities,’ he says, ‘and all regulated by and under the
perfect control of one will that is felt in every curved line.’ There
is some likeness to the ‘thousand personal activities of a regiment of
soldiers on their winding way.’ He has watched the creature ‘melting
into movements so intricate and delicate that the lithe and limbless
thing looks like gossamer incarnate.’
This Pine snake is very smooth, and in the excited actions thus
graphically described, it makes no noise like the little Indian viper;
but Mr. Lockwood’s words are so appropriate to both snakes that
the reader has only to add in imagination the rustling noise that
accompanies the quivering echis.
Among other of the ophidians remarkable for their hissing is _Psamophis
sibilans_, the ‘hissing sand snake,’ a very slender little creature.
Several mentioned by the earlier naturalists as ‘the hissing snake,’
are evidently _Heterodons_. Catesby, Lawson, and others mention one as
the ‘blowing viper;’ _Blauser_ of the Dutch, also the ‘chequered’ or
‘spreading-adder,’ which leaves no difficulty in identifying _Heterodon
platyrhinos_. An American writer indulges in a figure of speech while
describing this little Coluber by saying, ‘It emits a succession
of hisses, “sibilant sounds,” similar to letting off steam from a
small steam engine.’ He at the same time admits that it is harmless
and inoffensive in spite of its threatening aspect when flattening
its head.’ This is the ‘spread head’ alluded to in chap. xxii., an
unfortunate demonstration of alarm which has gained for it its venomous
titles. Several of this species have from time to time been added to
the collection at the Zoological Gardens, and the chief drawback to
their anticipated attractions is that they so soon become tame and
peaceful that you can scarcely provoke them to exhibit their reputed
power. I have seen one flatten its head so slightly as to be barely
noticeable, but I never heard it ‘hiss.’
‘Its spots become visibly brighter through rage,’ wrote Carver in 1796,
‘and at the same time it blows from its mouth with great force a subtle
wind that is reported to be of a nauseous smell.’ Chateaubriand, of
course, had something to say of ‘the hissing snake,’ frequent in the
warmer States of America. ‘When approached it becomes flat, appears
of different colours, and opens its mouth hissing. Great caution is
necessary not to enter the atmosphere which surrounds it. It decomposes
the air, which, imprudently inhaled, induces languor. The person wastes
away, the lungs are affected, and in the course of four months he dies
of consumption!’ Of another snake this author says, ‘He hisses like a
mountain eagle, he bellows like a bull!’
It may be objected, ‘Why occupy space by quoting such old wives’
fables?’ I reply, because they have already been so abundantly quoted;
and to such fables are in great part due the erroneous impressions
which exist to the present day. Several members of the _Heterodon_
family have from time to time been in our London collection. Friends
of mine have had _Heterodons_ in their keeping as pets; I have often
handled them, and found them gentle and inoffensive in every way. They
are indeed so popularly and peculiarly interesting that they will claim
a page presently, the present chapter being devoted exclusively to
ophidian lungs, not human lungs, supposed to be destroyed by them!
While admitting various degrees and qualities of hissing, we may give
a passing mention to Du Chaillu’s snakes, all of which appear to be of
the whistling, as well as of the ‘springing’ kind. He saw ‘an enormous
black shining snake, loathsome and horrid.’ ... ‘Then the fellow gave a
spring, and whistled in a most horrid manner.’ And when he was wounded,
he again ‘gave a sharp whistle.’ On another occasion, while a Goree man
was playing with a large Naja, ‘the air around seemed to be filled with
the whistling sound of the creature,’ and so on.
Another African snake, the ‘Green Mamba,’ has such very bad manners
that it not only hisses, but spits and darts at you. In this instance
my informant was a young lady, who had ‘seen it!’
Somewhat more perplexing, because more deserving of notice, is what
Livingstone tells us of a serpent called _Nega-put-sane_, or ‘serpent
of a kid,’ which ‘utters a cry by night exactly like the bleating of
that animal,’ and that he had ‘heard one at a spot where no kid could
possibly have been.’[42]
‘_Il canta como un gallo_,’ said Albert Seba of an astonishing snake in
Hayti and St. Domingo once.
‘Beyond a hissing and often a peculiar drumming noise, snakes emit
no sound,’ says Krefft, one of our very able authorities.[43] This
experienced writer does not positively affirm that the ‘drumming’
is produced by the voice, and it is more likely to proceed from
the beating of an agitated tail, an action which may be frequently
witnessed in excited snakes.
Dr. Otto Wucherer saw this in a South American snake, _Xenodon
colubrinus_. ‘It has the habit of striking the ground rapidly with the
tail when irritated’ (_Zoo. Soc. Proc._ 1861).
So do _Spilotes variabilis_, and some others. So also does the Pine
snake, whose tail ends in a horny tip, ‘like a four-sided spike,’ and
which vibrates like a crotalus in rudiment, or strikes the ground.
Several American naturalists have contributed interesting accounts
of this last species, known as the ‘Bull’ or ‘Pine snake,’ or ‘Pilot
snake,’ the largest of the N. American Colubers. It was this species
(_Pituophis melanoleucus_) whose actions Mr. Sam. Lockwood described as
mystic circles, and its activity as almost equal to that of the ‘Racer’
(_American Naturalist_, vol. ix. 1875). But it is called the Bull snake
because it ‘roars like a bull.’ Bartram went so far as to say like
thunder! ‘Said to hiss like thunder,’ or ‘resembling distant thunder,’
is the cautious testimony of Holbrooke, who adds, ‘but I never heard
it, though well acquainted with it.’
Mr. Lockwood minutely described one in his possession. In reading
his account we can but notice the similarity of action between this
‘Bull snake’ and the African vipers in ‘puffing,’ though regarding
the nature of the sound, the writer positively affirms that ‘there is
nothing sibilant in this blowing, not the slightest hiss about it.’
Mr. Lockwood records his experience of several that he had seen and
heard, and of a fight between one and a rat. ‘Now began that fearful
blowing. The snake slowly fills its lungs with air, and then expels it
with a bellowing sound that is really formidable.’ And again, in the
same volume, in reference to the former account, he says: ‘As there
noted, the _Pituophis_, when alarmed or enraged, slowly inflates itself
with air, thus nearly doubling its normal size along its entire length,
except the tail. It then slowly expels the air with its own peculiar
sound.’ He recalls his boyish terror on once hearing this sound, which
came upon him suddenly in a field, ‘like the restrained roaring of a
bull.’ This was in New Jersey; but the _Pituophis_ family extends to
the Western States, and to the Rocky Mountains, where ‘Bull snakes’
are frequently seen. In the reports of the United States Exploring
Expeditions, mention has been made of the prairie Bull snake, and of
others in Nebraska and as far west as California.
Some attain to seven feet in length; Holbrooke mentions one of nine
feet, and ‘as thick as your arm,’ in common parlance. An angry snake of
this size could, of course, blow with considerable force, and the term
‘bellowing’ might not unreasonably be applied to the sound; as it is
also applied to the croaking of the ‘bull frog’ (_Rana mugiens_), the
sound of which is really so like the lowing of cattle, that, on hearing
one for the first time in the woods of Virginia, I looked round, quite
expecting to see a young heifer in close proximity.[44] Probably, had
the bovine lungs sounded at the same moment, the reptilian ‘bellow’
would have proved but a feeble imitation. A sound out of place, so
to speak, or unanticipated, strikes upon the ear more forcibly than
when expected. But if one reptile, and that a very small one, can so
well imitate a bull as it is universally known the bull frog does,
why may not another do the same?—an argument which I venture to use
notwithstanding many herpetologists accept doubtfully the possibility
of a snake producing such a sound. ‘Il est difficile à concevoir
comment les serpents auraient la faculté de siffler, comme on pretend
que peuvent le faire certaines espèces de couleuvres, et comme les
poëtes se plaisent à nous les representer. Jamais nous n’avons pu
entendre qu’un soufflement très sourd, provenant de l’air qui sortait
avec plus ou moins de rapidité de l’interieur de leur poumon que l’on
voyait s’affaisser en trouvant une issue par la glotte, à travers
les trous des narines ou directement par la bouche dont la mâchoire
superieure est naturellement echanchrée. Alors la bruit était seulement
comparable à celui qui resulterait du passage rapide et continue de
l’air dans un tube ou par un tuyau sec et etroit, comme serait celui
d’une plume.’[45]
This no doubt answers to the ordinary ‘hissing’ of the majority of
snakes; but that the sound varies under certain conditions, and in the
same serpent, cannot be denied. A. R. Wallace relates an incident which
may well be introduced here, as affording both a proof of the length
of time snakes can sustain a sort of half suffocation, and also the
expression or power of ‘voice’ in breathing. A young boa was caught,
and in order to prevent its escape, its captors, while preparing a box
in which to convey it away, tied it tightly round the neck to a thick
stick, which not only fettered its movements, but appeared to nearly
stop its respiration. It lay writhing in much discomfort, sometimes
opening its mouth with a suspicious yawn, as if trying hard to
breathe. By and by, when relieved from its clog and safely consigned
to a box with bars on the top, it began to make up for loss of time by
breathing violently, ‘the expirations sounding like high-pressure steam
escaping from a locomotive. This continued for some hours, of four and
a half respirations a minute,’ when the breathing—in this case we may
say panting—gradually subsided, and then the poor thing settled down
into silence.[46]
The expression of feelings by the tail in so many snakes, producing a
sibilant sound in rustling dead leaves, and in some which are supposed
never to hiss, is a subject well worth the attention of scientific
naturalists. It would be interesting to ascertain if any peculiarity of
trachea or of glottis exist in these.
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