were winged serpents in Africa. Herodotus, on the contrary, says there
were none except in Arabia, and he went across the Red Sea from the city
of Bats in order to see them. He did not, however, succeed in doing so,
though he says he saw their dead bodies and bones. He says that they
hang about the trees in vast numbers, are of small size and varied
colour, and that they are kept in check by the bird known as the Ibis,
which on that account is held sacred, since they increase so rapidly
that unless devoured they would render it impossible for man to maintain
himself on the earth. They invade Egypt in swarms, flying across the Red
Sea. All this agrees with my suggestion that the winged “serpents” heard
of by Herodotus were really locusts; and the creature drawn in Fig. 27
may well be a locust transformed by fancy into a winged snake.
[Illustration: FIG. 26.—Egyptian four-winged serpent—as drawn on
ancient Egyptian temples.]
[Illustration: FIG. 27.—Two-winged serpent, symbolic of the goddess
Eileithya, from a drawing on an Egyptian temple.]
It would be a very interesting but a lengthy task to trace out the
origin and history of the various traditional monsters, such as the
basilisk, the gorgon, the cockatrice, the salamander, and the epimacus,
which have come into European legend and belief, and to give some
account of the special deadly qualities of each. St. Michael and St.
George slaughtering each his dragon and rescuing a lovely maiden from
its clutches are only appropriations by the new religion of the similar
deeds ascribed to Greek heroes, such as Hercules, Bellerophon, and
Perseus. Often a belief in the existence of a monster has arisen by a
misunderstanding, on the part of a credulous people, of a drawing or
carving showing a strange mixture of the leading characteristics of
different animals, which was meant by the man who made it to be only
symbolic of a combination of qualities. Just as the Latins and mediæval
people credulously accepted Greek symbolic monsters as real, and
transmuted Greek heroes into Christian saints, so were the Greeks
themselves deluded by strange carvings and blood-curdling legends which
reached them at various dates from mysterious Asia into a belief in the
actual existence of a variety of fantastic monsters. “The Greeks,” says
M. E. Pottier, a distinguished French writer on Greek mythology, “often
copied Oriental representations without understanding them.” The
conventional dragon probably came from Indian sources through Persia to
China, on the one hand, spreading eastwards, and to the Latins of the
early Roman Empire, on the other hand, spreading westwards; but at what
date exactly it is difficult to make out.
In mediæval, as well as in earlier times, marvellous beasts were brought
into imaginary existence by the somewhat unscrupulous enterprise of an
artist in giving pictorial expression to the actual words by which some
traveller described a strange beast seen by him in a foreign land. Thus
the “unicorn,” which was really the rhinoceros, was seen by travellers
in the earliest times, and was described as an animal like a horse, but
with a single horn growing from its forehead. The heraldic draughtsman
accordingly takes the spirally twisted narwhal’s tusk, brought from the
northern seas by adventurous mariners (the narwhal being called “the
unicorn fish”) as his unicorn’s horn, and plants it on the forehead of a
horse, and says, “Behold! the unicorn.” Meanwhile the real “unicorn,”
the rhinoceros, became properly known as navigation and Eastern travel
extended, and true unicorns’ horns, the horns of the rhinoceros, richly
carved and made into drinking cups, not at all like the narwhal’s tusk,
were brought to Europe from India. One was sent to Charles II. by “the
Great Sophy,” and handed over to the Royal Society by the King for
experiment. These horns were asserted to be the most powerful antidote
or destroyer of poison, and a test for the presence of poison in drink.
There was no truth whatever in the assertion, as the Royal Society at
once showed. Yet they were valued at enormous prices, and pieces were
sold for their weight in gold. A German traveller in the time of Queen
Elizabeth saw one which was kept among the Queen’s jewels at Windsor,
and was valued, according to this writer, at £10,000.
Credulity, fancy, and hasty judgment are accountable for the belief in
mythical and legendary monsters. Yet they have great interest for the
scientific study of the growth of human thought and of the relationships
of the races of mankind. They are often presented to us in beautiful
stories, carvings, or pictures, having a childlike sincerity and a
concealed symbolism which give to the wondrous creatures charm and human
value.
XIV
OYSTERS
Oysters are delicate morsels—still appreciated by that class of the
population which nevertheless shudders at the thought of eating the
high-flavoured “whilk” or the gristly “periwinkle,” and neglects the
admirable mussel, so rightly valued by our French friends. There are a
number of interesting facts about the nature and life-history of
oysters, and the different kinds of them—a knowledge of which does not
diminish, but, on the contrary, rather adds to the pleasure with which
one swallows the shell-fish. I remember the time when “natives” were
sold in London at sixpence the score. When I was a schoolboy at St.
Paul’s they were no more than sixpence a dozen at the best shops in
Cheapside. That inevitable form of British enterprise which is known as
“monopoly,” many years since laid hold of the oyster business, and
rapidly raised the price of the best natives to eight times what it had
been, while the typhoid “scare” came subsequently as a sort of poetical
justice, and threatened to ruin the oyster monopolists. As a matter of
fact, there is no difficulty in freeing oysters from any possible
contamination by the typhoid germ. They have only to be kept for ten
days or a fortnight in large tanks of sea-water of unquestionable
purity—after removal from the fattening grounds (tanks or waterways),
and they rid themselves of any possible infection. It is the interest of
the oyster merchant to make sure that this treatment is strictly
enforced. It is a noteworthy fact that the anciently established habit
of drenching an oyster with vinegar before eating it is precisely the
best treatment, except cooking them, which could have been adopted in
order to destroy the vitality of typhoid germs—although the existence
of such germs was unknown when the practice arose, and vinegar or
lemon-juice was taken with uncooked oysters as a matter of taste, not as
a safeguard.
The oyster is sometimes grandiloquently styled “the succulent
mollusc”—and it is classed together with other bivalve shells and true
“shell-bearing” shell-fish, such as whelks and snails (not lobsters and
crabs, which are Crustacea), in a great division of animals known to
naturalists as the Mollusca. This word is only a Latin form of the name
_Malakia_, which was given to the cuttle-fishes by that wonderful man
Aristotle, the Greek—and means “soft creatures.” A bivalve, or
two-shelled mollusc, like the oyster, may be compared to an oblong
notebook. The hard covers correspond to the two shells and the back to a
horny piece by which the two shells are united, forming the hinge. If
you place a piece of indiarubber (a thickish bit) between the covers of
the notebook so that it lies near the back, and then try to shut the
book, you find that it requires some pressure to do so; when you leave
off pressing them the covers gape. The horny hinge-piece or ligament of
the shells of the oyster and other bivalves acts in this way. The shells
are only kept closed by a strong muscle, which runs across from shell to
shell (Figs. 28 and 30_m_). When the oyster is at rest or when it is
dead the muscle does not act, and the elastic hinge-piece or ligament
causes the shells to gape. The animal within the shells may be compared
to the leaves of the notebook. Suppose there are twenty-six leaves, then
the outermost leaf on each side corresponds to the two soft living
membraneous flaps which secrete the two shells or covers of the oyster
and lie closely on them (_a_, _b_, Figs. 28 and 30); the next two on
each side (rather shortened leaves, folded in from below) are the flat
gills or “gill-plates” of the mollusc (_g^1_ to _g^4_ in Fig. 28);
whilst we must suppose the twenty middle leaves to be “pulped” and fused
together to represent the body of the shell-fish.
[Illustration: FIG. 28.—An oyster with the right-side shell removed;
_c_, the pearly inner surface of the left-side shell; _d_, the horny
outer layer projecting beyond _c_; _a_, the thick edge of the
“mantle”-flap of the left side; _b_, the thick edge of the mantle-flap
of the right side thrown back towards the centre, so as to show what
underlies it; _e_, notch in the surface (pulled a little upwards and
forwards) where the ligament is formed; _h_, the hinge surface, where
the removed shell rested on the left-side shell; _g^1_ to _g^4_, the
four gill-plates or flaps, two right, two left—the so-called beard;
_l_, the four corresponding lip lobes: the mouth lies deeply between the
second and third—that is between the right pair and the left pair; _m_,
the central shell-muscle, which runs from one shell to the other.]
[Illustration: FIG. 29.—Part of a row of the lashing hairs or “cilia”
which cover the gills of the oyster. This represents part of a single
row, only the 1/400th of an inch long from one end to the other. The
whole surface of the gill and other parts is beset with these hairs, not
in single rows, but closely, as the hairs of fur are set. The drawing is
intended to show the way in which the hairs actively bend downwards (or
“lash”), and then rise up again in regular waves, the movement or wave
passing along in the same way as a wave of bending and returning to the
upright passes over a ripe cornfield when a light breeze blows across it
(see also Fig. 40).]
The oyster’s gill-plates, commonly called “the beard,” are covered on
the surface by microscopic hairs of a very remarkable kind (Fig. 29).
They are soft, living protoplasm, and are continually “lashing,” bending
forwards and straightening again at the rate of some three or four
hundred strokes to the minute. They all work rhythmically together, and
produce a strong current in the water, which bathes the surface of the
oyster when the shells are open. Such microscopic vibrating hairs are
very common in aquatic animals, and are called “cilia.” The current
which they produce causes oxygen-holding water to flow from without over
the gills, and so aerate the blood of the oyster, and also carries into
the chamber protected by the shells excessively minute particles,
chiefly microscopic plants, which are driven on to the small, open mouth
of the oyster, placed far up on its body. These microscopic
food-particles are wafted down the oyster’s throat by similar vibrating
hairs into the stomach and intestine. An oyster has no other means of
taking food, and almost without cessation, as the oyster lies on the sea
bottom with its muscle relaxed and its shell “gaping,” the nourishing
stream is kept going. If poisonous matter, bad water, or some violent
disturbance make themselves apparent, the shell-muscle acts, and the
oyster tightly closes his shell. Such things make themselves “apparent”
to the oyster, for it has a nervous system, and though it has no eyes
(the nearly allied “scallop” has a number of eyes) it has a delicate
sense of smell and touch, and also what is usually considered to be an
organ of hearing.
[Illustration: FIG. 30.—The animal of an oyster removed from the shell:
_a_, the thick edge of the left side mantle-flap or skirt; _b_, same of
the right side; _l_, position of the mouth; _m_, shell-muscle or
adductor-muscle, bringing the two shells tightly together when it
contracts.]
The oyster has also a heart and blood-vessels (Fig. 30) and blood; in
some few bivalves and snails the blood is red like our own. The beating
of the heart may be seen by careful examination of a freshly opened
specimen. The oyster has also a “liver,” or digestive gland, and a
kidney and a soft, branched, tubular structure embedded in the body,
within which the egg-cells and sperm-cells grow by means of which the
oyster propagates itself in the summer. Our north European oyster
produces in the same individual both egg-cells, and the male fertilising
sperm-cells or spermatozoa. The eggs are just visible to the unaided eye
(Fig. 31), and as many as a million are produced in the warm breeding
season by a single ripe oyster. About a fortnight after the eggs have
been shed, the same tubular chambers in the oyster’s body which produced
the eggs by growth from their inner walls, produce the spermatozoa, so
that they are too late to fertilise the eggs of the same oyster. They
pass out of the oyster into the sea water, and are carried within the
shelter of the shells, and so on to the surface of the protected bodies
of other neighbouring oysters by the currents created by the “ciliated”
gill-plates of these neighbours.
[Illustration: FIG. 31.—The eggs of the oyster—taken from a ripe
individual—magnified 500 times linear.]
The sperm particles or spermatozoa (Fig. 32) are produced by millions,
and form a cloud finer than dust in the sea water. They are carried
within the shells of both egg-producing and sperm-producing oysters, and
are driven along into the openings of the tubular reproductive sacs,
and into those sacs in the case of those oysters which are at the time
producing eggs. There they fertilise the eggs. The minute eggs begin to
develop whilst still within the parent’s body, and continue to do so
whilst remaining within the shelter of the shell, adhering to the
gill-plates (Fig. 33). In a day or two each fertilised egg has developed
into a very minute creature, provided with a tiny circlet of cilia or
vibratile hairs, the movements of which cause it to swim (Fig. 33F). The
parent oyster is now said to be “white-sick.” In the course of a couple
of days the young oyster still within its parent’s shell becomes dark in
colour, and has formed on its surface a pair of symmetrical shells, not
like those of an adult oyster, but convex (Fig. 34) like those of a clam
or a cockle. The head region, with its circlet of vibrating cilia, can
be projected between the open shells or withdrawn between them when the
shells are shut. The mother oyster, laden with these little dark specks,
is now said to be “black-sick.”
[Illustration: FIG. 32.—The sperms or spermatozoa of a ripe oyster, as
seen swimming in a drop of sea water: magnified 2000 times linear.]
[Illustration: FIG. 33.—Development of the egg of the common oyster,
after fertilisation within the tubular passage of the reproductive sacs.
A, surface view. B, section through a very early stage—the separate
cells or protoplasmic corpuscles which have resulted from the dividing
up of the fertilised single egg-cell are seen; _bl_, in-pushing to form
the gut; _sk_, in-pushing to form the rudiment of the double shell. C
and D, the same a few hours later. The mouth, _m_, is now seen. E, still
later stage surface view: a ring of cilia has appeared. F, the young
free-swimming oyster nearly ready to leave its mother’s protection, who
is now laden with such young, and is said to be “white-sick.” The top of
the head, _tp_, is now well marked and surrounded by a ring of lashing
cilia. The outline of the right-side shell is seen, and the foot, _ft_,
between the mouth, _m_, and the anus, _a_. The stomach, _st_, and the
intestine, _e_, show by transparency.]
In the course of a week or so the brood of dark young oysters escapes by
thousands from the parent’s shell into the surrounding water. They swim
by their circlet of vibrating hairs, or “velum,” as it is called,
towards the surface, and are carried far and wide by the tides. They are
active, transparent little “dots,” very unlike their parent (Fig. 34).
The next thing that happens to them—after a few days, perhaps weeks—is
that owing to the increasing weight of their shells, they sink to the
bottom. More than half perish by dropping thus on to bad ground; a
vast number have already been eaten by young fishes and shrimps. Those
which are lucky enough to fall on to something hard—stones, rocks, old
oyster-shells, or the shells of living oysters—become cemented to those
hard substances by the new shelly substance formed by the growing edge
of the lowermost of their little shells, which now spread out, lose
their cockle-like shape as they grow, and become, the one (the left by
which it is fixed) large, deep, and bossed, the other flat. The little
oysters are only one-fortieth of an inch in diameter when first they
become fixed, but they grow rapidly, feeding in the same way as their
parents. Vast numbers are eaten by other animals. In some localities in
two years, in others in three years, they have grown to a couple of
inches in length, and now produce in the summer breeding season a
certain quantity of eggs and sperm to start new generations. The oyster
continues to grow, and at five to seven years of age is in full vigour
and maturity; at ten years of age it produces few eggs, or sperm-cells;
and in the course of another year or so, under natural conditions, dies.
[Illustration: FIG. 34.—Free-swimming young oyster or oyster-larva,
showing the head, with its tuft of cilia projecting from between the two
shells, _l_ and _r_.]
Enormous as is the output of young by a single oyster—amounting to
something like a million a year in probably four or five successive
years—yet it must be remembered that on the whole, taking all the
various oyster-beds into account, some of which increase whilst others
dwindle or actually die out altogether, there is no increase in the
oyster population of the seas. Taking them all round, five million young
oysters start life in order that one may finally come to maturity, so
many and varied and incessant are the dangers, the predatory enemies,
the destructive effects of cold currents, bad ground, and other chances
of life and death on to which the swarming swimming young are launched.
The above brief history applies to the North Sea or Channel oyster,
which is also found (with other species) in the Mediterranean. The
American and the Portuguese oyster differ from it in being of distinct
sexes, and in the fact that the eggs are discharged into the sea by the
females, and are there fertilised by the sperm discharged by the male
oysters, instead of in the parent’s body.
Other “molluscs,” such as snails and whelks, enclose their fertilised
eggs, when they lay them, in egg-shells. Some snails enclose a single
egg in a shell which is filled up with clear liquid—corresponding to
the “white” of a bird’s egg—in which the egg floats and develops. The
eggs of the common snail are not bigger than a hemp-seed, but some
Indian snails lay eggs as big as those of a robin, with a hard,
calcareous shell, and the young snail has quite a large coiled shell of
its own before it escapes from the egg-shell. So that it looks, when one
of the big snail’s eggs is broken, as though a snail had managed to get
inside a bird’s egg without making a hole in it! The whelks and their
kind lay many eggs in one shell or capsule, and the sea-slugs produce a
sort of firm jelly, in cords like vermicelli, the jelly enclosing
hundreds of little sacs filled with liquid, in which the true germs or
fertilised egg-cells float. These are all methods for protecting the
young in their earliest condition. One of our pond-snails—the
_Paludina_—keeps her eggs, whilst they develop, inside the dilated end
of the tube which leads from the egg-producing organ or ovary to the
exterior. The young snails nearest the opening to the exterior are the
furthest advanced in development, and are as big as a dried pea. All
stages, from the minute germ just fertilised to well-formed young, may
be found in these snails, and the whole course of their development and
gradual change and growth can be minutely studied with the microscope in
one specimen.
Similar devices for protecting the young in their earliest helpless
stages of growth from the egg-shell are found in all classes of animals.
What is very curious is the fact that, of two closely allied animals,
one species will recklessly lay its eggs and leave them, whilst another
has special arrangements for retaining in the parent’s body the eggs as
they develop, and so preserving them from danger. Such parents are
called “viviparous.” Of course, in all viviparous animals, as well as in
those which lay their eggs in hard shells, the fertilisation of the egg
must be effected within the maternal body. Amongst our common fishes
there is the viviparous blenny, often found in pools at low tide on the
seashore. All the other British fresh-water and marine fishes lay their
eggs and abandon them, excepting some sharks, dog-fish, and skates,
which are viviparous; others of the shark and skate tribe lay eggs of
large size encased in hard, horny shells. Every one knows that frogs and
toads lay their eggs, but there are some kinds in which the eggs remain
inside the mother’s body during the development of the young, which only
escape into the world as well-formed little frogs. All the hairy,
warm-blooded quadrupeds known as “the mammals” are viviparous, except
the duck-mole and the spiny ant-eater of Australia. These extraordinary
little “beasts” lay eggs like those of a bird.
The most ingenious devices for the protection of the young are (as
perhaps those who believe in the superior intelligence of the male
would expect) put into practice by the male parent. Thus, there is a
large fish in tropical rivers which takes the eggs laid by the female
into his capacious mouth, and swims about with them for three or four
weeks, giving them the advantage of a current of water which runs
through his mouth to his gills. When the young hatch they swim out of
their fond father’s mouth. The male of pipe-fishes and of the little
“sea-horse” receives the eggs laid by the female into a pouch excavated
along his ventral surface. There the young hatch, and are guarded by the
nursing father. On the other hand, some fathers impartially eat their
own young, as well as those of other parents, and the mother has a hard
job to protect her offspring. A female octopus (the poulp or eight-armed
cuttle-fish) sits over her eggs in a nest built of pebbles at the bottom
of the sea (or of an aquarium tank in the instance studied by me many
years ago at Naples), and squirts a stream of pure sea-water over them.
She resents the approach of a fish or a crab or a landing-net with
splendid fury and recklessness of attack. Often the males of fishes,
frogs, and birds guard the eggs, or guard the nest where the female is
occupied in caring for the eggs or the young.
There are various species of oysters common in all parts of the world
which are eaten as delicacies. Primeval (Neolithic) man ate oysters (the
common sort) in Denmark in enormous quantity—great heaps of the
discarded oyster-shells are found, buried among which are discovered
stone axe-heads and bits of rude pottery. In the West Indies travellers
relate that the oysters “climb” the trees which overhang the water of
quiet creeks and inlets of the sea. The fact is that the branches of the
mangrove trees dip into the water, and the young oyster “spat” attaches
itself to the immersed twigs. After a year or two, the tree grows
vigorously, and raises its branches up in its growth, so that the
oysters are carried far up above the sea waves. Of course they die under
these conditions, but their position suggests the explanation that the
oysters have climbed up the trees. Ship barnacles fix themselves,
similarly, to the twigs of willow trees in the quiet sea lochs of the
West of Scotland, and this led 500 years ago to the belief that the
catkins of the willow tree ripen into barnacles. Since it was also held
that the little animal of the barnacle hatches out of its shell as a
young goose—the so-called “barnacle goose”—the marvellous story was
believed that these geese are actually budded from willow trees. I
believe that the supposed relationship of the goose and the ship’s
barnacle arose solely from the accidental similarity of the names of the
two animals—the “bernack” goose and the sea “barnacle” being names of
independent origin. The names were different originally in sound and
signification, but were corrupted by fisher-folk into one and the same
word. Hence a fantastic fable took its growth.