roots of trees, among the stubs of a coppice, under a brushwood pile or
fernstack, in order to pass the winter in sleep. As a rule, several or
many associate in hibernation, and when found they are usually twined
together in intricate knots. Here they remain until March or April, when
the Frogs, Toads, and Newts, emerging from a similar retirement, are
available for a good meal. About this time the males seize the females
in their jaws, and with their bodies entwined pairing takes place. Some
time between June and August the female seeks some convenient mass of
fermenting vegetable matter amidst which to burrow and deposit her
eggs. If a heap of fresh stable manure is available she will prefer
it, the heat hastening incubation. The eggs--which may number a dozen
or anything up to four dozen--are equal-ended ovals with a tough,
parchment-like shell, and all connected in a string. As soon as laid
they begin to absorb moisture from their surroundings, and increase in
size until they are about an inch and a quarter in length. They hatch
in from six to ten weeks, according to temperature, and the baby Grass
Snakes measure from six to eight inches. Before hatching they are
provided with a special egg-tooth projecting from the front of the jaws,
which enables them to pierce the egg-shell. It soon becomes loose and
drops off after its special function has been performed. The young Snake
sheds its skin before taking its first meal, and thereafter goes through
the same process four or five times in a year.
The Grass Snake appears to have a life comparatively long. The female is
about four years old, with a length of two feet, before she begins to
breed. Gadow mentions a fine female which he had alive for nine years,
and during this period her length increased from thirty-five to
forty-two inches.
Although the Grass Snake may be found frequently about ponds and ditches
where there are Frogs, Toads, and Newts to be caught, it is by no means
restricted to such resorts, but may be met with on chalk hills, sandy
heaths, and other places far removed from water. In addition to the
amphibians mentioned, it feeds occasionally on fish, mice, and small
birds. The young Snake takes worms, tadpoles, and the young of newts,
frogs, and toads. It swims well and often enters the water to obtain its
prey. Although an agile reptile, it may be caught without difficulty
where the ground is not too rich in mouse runs or too well covered with
furze. The undulations by which it progresses are always horizontal, not
vertical as sometimes represented by imaginative artists. When captured
it seldom makes any attempt at biting, though it will hiss freely and
snap its jaws. It usually seeks rather to disgust its captor by the
voiding of a fetid secretion with a strong odour of garlic among other
objectionable scents. It soon becomes gentle and tame.
The Grass Snake is widely distributed over England, Wales, and the
south-eastern parts of Scotland. It appears never to have reached
Ireland. Various attempts have been made to introduce it in the latter
country, but the prejudices of the people and their respect for the
legendary miracle of their patron saint have always prevented the Snakes
from establishing themselves.
*Smooth Snake* (_Coronella austriaca_, Lacepede).
Although in general appearance similar to the Grass Snake the Smooth
Snake in the hand exhibits a sufficient number of differences to make
its identification easy. The smoothness which gives it a name is at
once evident to our sense of touch, and is due to the fact that all its
scales lack the little keels or ridges that give a certain roughness to
the common species. It never attains to so large a size as the Grass
Snake, its maximum length being two feet.
The ground colour of this snake on the upper side is grey, brown, or
reddish, with small black, brown, or red spots, which are usually in
pairs; occasionally there are three lighter longitudinal stripes. The
upper part of the head is sometimes blackish; this is more frequently so
in young examples. A dark streak runs from the nostrils and through the
eye to the angle of the mouth. This streak may be prolonged, even to the
tail. On the underside the colouring is some tint of orange, red, brown,
grey, or black, with or without black spots or dots. The eye has a round
pupil like that of the Grass Snake, and this helps to give it a similar
gentle appearance.
Prior to the year 1853 British specimens had been regarded as mere
variations of the Grass Snake, but in that year it was captured by Mr.
F. Bond at Ringwood by the New Forest, though it was not recorded under
its proper name until six years later. It has been found since in other
parts of Hampshire, in Dorset, Surrey, and Berkshire; in some places
abundantly, especially those in which the Sand Lizard occurs, this being
the Smooth Snake's favourite prey. Its usual resorts are heaths, stony
wastes and wooded hillsides. Its food consists mainly of Lizards, but
it also takes young Snakes and Slow-worms; occasionally it consumes mice
and mice-like mammals including the Voles and Shrews. When these are
sufficiently large it is said to coil around them in Boa-constrictor
fashion.
Pairing takes place soon after emergence from hibernation in spring.
As in the case of the Slow-worm and the Common Lizard, the eggs are
retained until the young are ready to hatch out, and they are born about
the end of August. They vary in number from two to fifteen, but usually
there are about six to a birth. They are enveloped in a thin membrane
which is ruptured immediately, and the Snakes are seen to be about five
or six inches in length.
Like the Grass Snake this species emits an objectionable odour when
captured, and at first attempts to bite, but this unfriendly phase
passes quickly, and it becomes perfectly tame and exhibits a
considerable amount of intelligence.
It may be as well to add that, if we count the rows of small scales
on the back and sides of either of our non-venomous Snakes, we shall
find there are nineteen of them. In the Viper there are twenty-one
rows--rarely nineteen or twenty-three. Each one of these scales is
marked with a tiny pit which appears to coincide with the end of a nerve
fibre, so that one may say the sense of touch resides in every separate
scale. The head is less distinct from the body than is the case in the
Grass Snake; and the slender tail is one-fourth of the entire length in
the male and one-sixth in the female.
The Smooth Snake is found throughout the greater part of Europe.
*Viper or Adder* (_Vipera berus_, Linn.).
At a superficial glance the Viper is quite distinct from our other
Snakes. Instead of the long, gracefully tapered body of these, the
Viper is short and thick in the body with a short tail. So far as
the length is concerned, the average Viper is less than two feet. A few
exceptionally large females have been recorded measuring two feet eleven
inches; but the female is always slightly longer than the male--usually
about an inch more. Two feet three inches may be regarded as the
ordinary maximum for a female. The head is flatter above, and it
broadens behind the eyes, so that it is very distinct from the body;
further, the shields on the head are very much smaller than the
corresponding plates of the Grass Snake. The iris of the eye is
coppery-red, and the pupil is vertical--which usually denotes nocturnal
habits, but the Viper is active by day as well as by night, and is fond
of basking in the sunshine.
Respecting colour, there is a considerable range of variation, much of
it sexual; but, generally speaking, it may be said to be some tint of
brown, olive, or grey, and this ground colour may be so dark that the
darker markings are scarcely perceptible on a cursory view. Along the
sides there are whitish spots, sometimes reduced to mere dots. The
brown, red-brown, or olive males have black markings; the grey or
whitish males are marked with brown or black, and have the underside
black. The throat is black, or whitish with scales spotted or edged with
black.
The females if brown or brick-red have dark brown or red markings; olive
females have brick-red bands or spots. The yellowish-white chin and
throat are sometimes tinged with red. The eyes of the female are smaller
than those of the male.
The markings are subject to a good deal of variation as well as the
ground colour. The usual wavy or zigzag line down the centre of the
back, with a series of spots on either side, may be broken up into oval
spots; and the characteristic pair of dark bars on the head may form
either a */\* or an *X*. The broad shields which cover the lower surface
may be grey, brown, bluish, or black, or bluish with triangular spots of
black, sometimes with white dots along the margins. Below the end of the
tail the colour is yellow or orange. Specimens have been recorded almost
entirely of a rich black, the excepted portion being the whitish
underside of the head and throat.
The usual haunts of the Viper are sandy heaths, dry moors, the sunny
slopes of hills and hedgebanks, bramble clumps, nettle beds, heaps of
stones and sunny places in woods; but we have also found it in heathy
and grassy places that were distinctly and permanently wet. For food
they appear to prefer small mammals such as mice, shrews and voles,
young weasels; but also take birds, lizards, slow-worms, frogs, newts,
and large slugs. The young subsist for a time on insects and worms.
The Viper retires in autumn to a hollow under dry moss among the
heather, under faggot stacks or into the discarded and leaf-covered
ground nests of birds. They reappear about April, and may then be seen
coiled on a sunny bank, apparently more concerned to absorb heat than
to find food. They pair at this season, and the young (varying from
five to twenty) are born in August or September. In this species, again,
the eggs are retained until fully developed, and when the young see the
light they are coiled up tightly in a thin, transparent membrane, which
usually breaks during the process of birth. They measure from six to
eight inches, and are at once independent.
The hoary old legend about the mother Viper opening her jaws to afford
sanctuary to her young in time of danger has probably arisen from some
occasional acts of cannibalism. It presupposes what is not true of any
of our reptiles--that the young remain with their parent. They all begin
life equipped for independence, and act accordingly.
The Viper is not so amenable to a life of captivity as our other
Snakes. It is not amiable, indeed its temper may be described as short
and sulky, which it displays by refusing all offers of food; most
captive Vipers die of starvation, the "hunger strike" being their
effective protest against the deprivation of liberty. On being captured
they are always ready to bite; but in a state of freedom the Viper is
not the aggressive monster that is popularly supposed. It seems to
depend largely upon its inactivity for escaping observation, but when
it knows it has been discovered its immediate impulse is to seek cover.
Accidents from Viper bites are rare in this country, where people go
about well shod, and there are very few cases of authenticated death
from this cause. On the Continent, however, such cases are frequent;
and it is suggested that in the warmer parts of Europe, where bare feet
are more numerous, the Viper's venom may also be more active than it is
here. It is the toes or fingers that are most likely to be bitten, for
the Viper's mouth is not large enough to enable it to bite the larger
parts. The mechanism by which the poison is introduced into the blood of
its victim has been briefly described on page 146.
[Illustration: _Pl. 96._ _L 156._
*Viper or Adder.*
Vipera berus.]
[Illustration: _Pl. 97._ _L 157._
*Edible Frog.*
With vocal sacs inflated in "singing".]
It must not be supposed from the foregoing remarks that we deprecate
caution in dealings with the Viper; but we do desire, if possible, to
dispose of that senseless fear that is unworthy of man. If the victim
is in bad health the bite of the Viper may involve very unpleasant
consequences--even death, but this is much more likely to follow from
the sting of a gnat! In case of a bite from this species, the approved
treatment is to suck the wound thoroughly and apply oil to it. The
rustic remedy approved by quack doctors is an oil prepared from the
Viper's own fat--"a hair of the dog that bit you" sort of cure. A
ligament above the wound will prevent the poison spreading; and the
blood may be made alkaline by the internal administration of ammonia.
The popular idea in many parts is that the reddish coloured Vipers have
more virulent poison than the others, but there does not appear to be
any good grounds for this differentiation.
The Viper is found in all parts of Britain, but is not known in Ireland.
AMPHIBIOUS ANIMALS: FROGS, TOADS, AND NEWTS
*Frog* (_Rana temporaria_, Linn.).
With the Common Frog, popularly classed as a Reptile, we commence
acquaintance with the zoological class Batrachia, creatures that
begin life at a much lower stage of development and have to pass
through a fish-like larval form before attaining to any likeness
to their parents. The Reptiles get through these developmental stages
whilst they are still in the egg; they never have water-breathing
organs. The Batrachians or Amphibians are clothed with soft skin which
is not protected by armour plates or scales as seen in the Lizards and
Snakes, but through which they are able to oxygenate the blood. The
Frogs, Toads, and Newts constitute a class intermediate in structure
and development between the Fishes and the Reptiles. Our native
species represent the two orders--Ecaudata (tailless), including the
Frogs and Toads; and Caudata (tailed) comprising the Newts.
Everybody knows the Frog as well as they know any of the backboned
animals, and every youngster even is familiar with the main facts of its
development, from the jelly masses of eggs in the pond early in spring,
through the tadpole stage to the attainment of four legs and wonderful
leaping powers. It is common knowledge that he has a moist, smooth skin
(the supersensitive erroneously say "slimy") of yellowish ground colour
overlaid with streaks and spots of brown. There is a big patch of brown
behind each eye, and the long hind legs have cross-bars of the same
colour. The ground tint of the Frog varies in different individuals
according to the situation in which we may find them; for the pigment
cells of the skin expand and contract under the influence of varying
intensities of light reflected from the surroundings, causing colour
changes much after the manner of those of the Chameleon, though less
marked.
[Illustration: *Skeleton of Frog.*]
The Frog's forelimbs are very short compared with the hind pair,
and the four moderate-sized fingers are not connected by webs; whereas,
the hind limbs have their several bones lengthened, and the abnormal
lengthening of those of the ankle gives the legs the appearance of
having a supplementary joint. The leg is one and a half times the length
of head and body. The foot has five long toes connected for half their
length by a "web" of skin which constitutes a very efficient paddle when
the Frog is in the water. Of these hind toes the fourth is considerably
longer than the long third and fifth.
The Frog's head is as broad as it is long, the muzzle rounded, and the
horizontal gape of the mouth extends back beyond the eye. The prominent
eyes are perched up on the forehead, and have a fine golden iris and a
horizontal pupil. The Frog differs from the Snakes and agrees with the
Lizards in having eyelids; he has also, like the Birds, an additional
lid--the nictitating membrane. There is a row of delicate teeth along
the upper jaw, but none on the lower; there are others on the palate.
The deeply notched tongue is attached by its base to the front part
of the mouth, the tip far in towards the throat; in use it has to be
suddenly turned over so that the tip is projected far beyond the muzzle.
The large circular depression behind and below the eye is the drum of
the Frog's ear.
The Frog has no neck, the base of his skull coming close to the
collar-bones, and there are only a few pairs of very short apologies for
ribs between the shoulders and the long pelvis which produces that steep
incline at the rear of his back. He is clothed entirely with a smooth,
soft skin, which is kept moist by the action of minute mucous glands
distributed all over the body. A row of these glands of larger size
forms a pale line running back from the eye on either side. The skin
plays an important part in the oxygenation of the Frog's blood; and the
experimental physiologists have shown that a Frog deprived of its lungs
can carry on its respiration for a lengthened period through the skin
alone. Owing to the absence of ribs he has to fill his lungs by
swallowing air.
The male is less portly than the female, and he is further distinguished
by having two pads on the first finger which in the breeding season
become large rough cushions enabling him to hold his mate. In his throat
there is a pair of vocal sacs enabling him to produce his love songs,
and when these are in use their inflation causes a distension of the
skin of the throat; but without these adjuncts the female manages to
give answering croakings. When these duets are sung under water they
produce some curious effects.
When the pairing season arrives--quite early, usually about the middle
of March, but sometimes in February--all the Frogs that have just come
out of hibernation select their mates. Any pool of water will do,
however transient, and they often make mistakes in this matter, their
egg-masses being left high and dry when the waters dry up. The eggs are
deposited in a mass of a thousand to two thousand at the bottom of the
water, and at first they are only about a tenth of an inch in diameter,
but the gelatinous covering absorbs so much water that they swell up to
a third of an inch. There is a corresponding lightening of the mass,
which floats to the surface and is available for observation. Each
of the little jelly-spheres is seen to have a black centre--the egg
proper--with a white spot on the lower side. If the spring is an average
one, in about four weeks' time the black specks will have developed into
brown larvæ or tadpoles, and having escaped from the egg these will be
clinging to the remains of the jelly mass by means of a pair of suckers
on the underside of the head. There are at present no indications
of limbs--head, body and tail, like those of a fish, merge one into
another. Even the gills are not yet developed, though what we may term
the buds of them are seen on the bars separating the slits behind the
head on each side. These buds soon expand into gill-plumes through
which the blood circulates, taking up oxygen from the water that passes
between them. There is as yet no mouth, but this will soon open, and
horny plates on its jaws will enable the tadpole to crop soft vegetable
matter, upon which it subsists chiefly. Later on, the gill-plumes will
be hidden by a flap which grows over them. The full series of stages in
this development may easily be watched by keeping a few tadpoles in a
glass of water with a little growing pond weed.
Ultimately, the limbs appear. Though all four develop simultaneously,
the hind pair _appear_ first, because the forelimbs are at first hidden
by the flap which grew over the gills. After the disappearance of
the gill-plumes, proper lungs are developed inside the body, and the
animal changes from a fish-like water-breather to an air-breather, in
preparation for a life on land. When all the legs are well out the form
of the tadpole soon changes to that of the Frog, except that it has a
long tail. You may read in some books that the tail is shed, but this
is a mistake that no one could make who has watched day by day the
evolution of the Frog from the tadpole. The tail is _absorbed_; it gets
smaller daily, until finally the hind body is rounded off and there is
nothing left to indicate that it once ended in a tail. Ultimately the
Frog may attain a length of head and body equal to four inches.
[Illustration: _Pl. 98._ _L 160._
*Common Frog.*
Rana temporaris.]
[Illustration: _Pl. 99A._
Spawn mass soon after deposit.
*Development of Frog's Eggs.*]
[Illustration: _Pl. 99B._
Eggs apparent after absorption of water.
*Development of Frog's Eggs.*]
[Illustration: _Pl. 99C._
Germs assume Tadpole form.
*Development of Frog's Eggs.*]
[Illustration: _Pl. 99D._
Tadpoles begin to hatch out.
*Development of Frog's Eggs.*]
[Illustration: _Pl. 100A._
Immature Tadpoles on outside of egg-jelly.
*Early stages of Common Frog.*]
[Illustration: _Pl. 100B._
Tadpoles begin to leave. Egg-jelly decomposing.
*Early stages of Common Frog.*]
[Illustration: _Pls. 100C,D,E,F._
Rise and decline of tail, and development of limbs.
*Early stages of Common Frog.*]
[Illustration: _Pl. 101._ _M 161._
*Edible Frog.*
Rana esculenta.]
Mr. E. S. Goodrich, F.R.S., has recently demonstrated that eggs obtained
from a female Frog by dissection can be fertilised by the leucocytes or
colourless corpuscles of the blood. He exhibited a fatherless Frog, so
obtained, before the Linnean Society in November, 1918.
When all the tadpoles have become real little Frogs, with their legs
sufficiently firm to enable them to indulge in hopping exercises, they
still for a time venture no further than the very shallow water at the
extreme edge of the pond, where they can walk partially submerged. Then
one day there comes a heavy summer rain storm--a deluge on a small
scale. Every little Frog then appears to hear the word "Go!" for with
one impulse they all scramble out of the pond into the jungle of wet
grass, they know not whither. If there is a road near, that is the place
in which to form an idea of their prodigious numbers. The few wayfarers
who may be hurrying along that road, looking for possible shelter from
the pitiless rain, and seeing the Frogs hopping along much as the
raindrops bounce, are quite prepared to declare that they came down from
the clouds with the rain. Many persons who in the ordinary affairs of
life would be regarded as reliable witnesses have testified that this
is what happens. To them it seems a much more reasonable explanation of
this sudden appearance--they term it a phenomenon--than the naturalist's
statement that the Frogs had been waiting in the pond for the psychical
moment to arrive for their dispersion--the time when the reeking herbage
of many acres around would offer the safest conditions for their tender
bodies to embark on the great adventure of life, their distribution over
wide areas where they could carry out their proper function, the control
of any inordinate increase in the insect population. For months they
will crawl and hop invisibly among the lush grass and journey through
the dense herbage of hedgebottoms and spinneys. Some will come under
fences even into our gardens, to help us in an unequal warfare in which
the gardener is always defeated by the insect, whether the bigger
combatant admits it or not. Their food consists entirely of insects,
slugs, and worms. In turn the Frog constitutes the food of many larger
animals, including fishes, birds, snakes and weasels. The winter is
spent embedded in mud at the pond-bottom, or in damp holes in the earth.
The Common Frog is distributed widely all over Britain, but is only of
local occurrence in Ireland. Abroad it ranges over Central and Northern
Europe as far as Sweden and Norway, and eastward to Mid-Asia.
*Edible Frog* (_Rana esculenta_, Linn.).