have a black spot on one side. They are found embedded many together in
a colorless jelly-like substance. The egg-mass should be handled
carefully and put whole into a jar or pail of water and thus carried
home. It should not stand with the sun shining directly on it, and when
the water is changed, every other day, that which is used should be of
about the same temperature as that removed. Water drawn cold from the
pipes will sometimes kill the eggs.
If all goes well, in a few days the eggs will hatch. Out of them will
hatch, not frogs, but tadpoles, or pollywogs, as they are also called.
Everyone likes to watch a tadpole--certainly every child does. As soon
as the eggs hatch, the surrounding jelly substance may be thrown away,
merely as a matter of convenience. Its use is to protect the eggs and to
afford the first food for the tadpole. If left too long in the water, it
becomes broken up, discolored and unpleasant. The tadpoles should have
fresh water every day or two, care again being exercised not to use it
too cold, and they must be fed. They will eat almost anything, crumbs of
crackers or bread, and bits of raw meat or fish being very acceptable.
If they are well fed on meat or fish, they will grow faster and change
earlier into frogs. Indeed, by underfeeding tadpoles a person can keep
them a whole year from undergoing the changes they would have normally
undergone in a few weeks. The large bull-frog tadpoles naturally take
two years to develop, though a very nutritious diet may possibly hasten
them.
[Illustration: TADPOLES AT DIFFERENT STAGES OF GROWTH]
The tadpole has very small eyes, a very small mouth, and tiny gill
openings like a fish. Indeed, so far as its life at this stage is
concerned, to all intents and purposes it is a fish. It cannot live out
of the water, it breathes by gills, it swims by its tail, but it has no
fins. It wiggles about the jar or tank in a very lively way, and ought
to have water weeds or stones to hide under, and pebbles or gravel in
the bottom of the receptacle.
The ordinary tadpole, if well fed, astonishes and delights his young
keepers in a few days by putting forth a pair of tiny hind legs, which
generally trail behind him when he swims, though he often kicks with
them, perhaps for exercise. He grows larger and his legs longer, and one
day a row of fingers may be seen peeping out of his gill slit, as though
out of an armhole, and then he will thrust out a forearm, then another
from the other gill slit. After this, changes are rapid, and his keepers
should put a stone or some firm object in the water, reaching above the
surface, so that he can climb up into the air; for now his lungs are
rapidly forming, and soon he can no longer breathe by gills. At this
stage, his tail begins to disappear. It does not fall off, as some
think, but its substance is absorbed into his body until no tail is
left. Finally, his head changes its shape, his baby mouth is replaced by
a wide frog mouth, his eyes stand out with projecting lids, his
ear-plates showing back of them, and we have a full-grown frog.
To the child who understands the origin of the fish eggs a few
questions which he can easily answer himself will be enough to call
attention to the important differences, and also to deepen the
impression of the unity of life as expressed in flower, fish, and frog.
The ova of the frog develop in an ovary exactly as do the ova of a fish;
they develop in the same way and at the maturity of the animal. The
fertilizing cells develop like those of the fish. In both cases, the
reproductive elements are laid, shed, or born, when the time comes.
Before the eggs of the frogs and toads are laid they have no albuminous
covering. The moisture that envelops them swells up into the jelly-like
mass upon coming in contact with water.
There are important differences between the frog and the fish. The frog
is a more complex animal and, so to speak, more difficult to create, and
it lays fewer eggs. Since there are fewer eggs they must be more
carefully fertilized; that is, the fertilizing material must be sure to
come in contact with all of them. Consequently at the moment when the
eggs are finding their way into the water they are fertilized; not
within the female body, but just as they are leaving it.
The child accustomed to notice what he sees will observe the paired
frogs in the pond. He can be told that they take this position just
before the eggs are laid so that every egg will surely be fertilized. In
the amphibious animals the relation of the two parents is closer than in
the fishes, but yet there is no union between them, that appearing only
when it is necessary. The stern law of necessity governing every step of
the reproductive function may be made very impressive to the young mind;
also _the reign of law_ throughout life.
To explain frankly, simply, and scientifically such phenomena as that of
the paired frogs will tend to rob them of dangerous interest. Not to
speak of them will not prevent the child's seeing them, and his
imagination may foster much less wholesome thoughts.
There are frogs and toads that care for their young, but parental
affection in this form of life is rare. The eggs are laid in a favorable
spot, and then left. Toads as well as frogs lay their eggs in the
water. The instinct of the toad leads it to seek the water at the
egg-laying season, as its tadpole, like that of the frog, can live only
in the water. At other seasons of the year the toad does not enter the
water.
Frogs' eggs are laid in compact masses, while toads' eggs are laid in
strings or ropes; and in this way they can be recognized, though after
they have once hatched the tadpoles of both are so much alike that they
cannot be told apart. Sometimes the children will be disappointed
because the tadpole does not change into a frog nor yet into a toad. It
gets its four legs but does not lose its tail; it never loses its tail.
In short, it is not a frog or a toad, but a salamander or water-lizard,
which lays eggs similar to those of the frog, and whose young upon first
hatching look very much like young tadpoles.
If eggs are found in a pond where frogs are not heard or seen, they will
almost always turn out to be the eggs of a salamander.
X
THE BIRD
From the flower to the bird is a step easily taken if the parent prefers
to omit the intermediate steps, or, after the story of the bird has been
told, the stories of fish and frog can follow as occasion offers,
instead of preceding it. The bird is peculiarly valuable in teaching the
origin of life to the child, since in it we have such highly developed
home and family instincts, the father bearing his share of the burden,
illustrations of which are rare in the lower forms of life. As
everywhere else, the best starting-point is with the life and interests
of the bird itself, and for this caged birds are far better than the
free ones, even though they may be only the sparrows and pigeons of the
city streets.
The flight of birds is that which particularly interests children as
well as every one else. Birds will soon learn to come to a place where
they are fed regularly; and the style of flight, depending upon the size
and shape of the wing as well as the shape of the bird's body, is a very
interesting study. Many a country child knows the common birds by their
flight even when the bird is too far away and moving too fast to be
distinctly seen. What he generally does not think of is _why_ the bird
has this peculiar flight, and to have his attention called to it may
increase his interest in watching the living bird.
Whatever increases the boy's interest in the live bird tends to decrease
his desire to make it a dead bird; and the numerous good bird-books, as
well as the substitution in so many cases of the camera for the gun, has
tended to preserve the lives of the birds and to create a sentiment in
favor of their preservation. If the young child is taught to watch the
birds and care for them, he will not often, when older, thirst to take
their lives.
While the flight of the bird may engage the first interest of the child,
its manner of eating and drinking is worth attention, and the nature of
its food is of the greatest importance. The shape of the bird's beak
will decide, at least in a general way, the kind of food it eats; and a
little study of birds will convince any one that all birds are useful to
the agriculturist, either as destroyers of noxious insects or of weed
seeds. While some birds swallow the seeds whole and pass them again
unharmed, thus spreading the plant, others crack the seed coat and eat
the contents, which of course destroys the seed. Even where the birds
are the means of sowing seeds they do more good than harm; for the seeds
thus sown are not often harmful, and those same birds destroy a vast
number of noxious insects. Even owls and hawks, by destroying mice in
the farmer's fields, do him a service that much more than compensates
for the loss of an occasional chicken.
While the birds are of inestimable value to the farmer and to any one
who has a garden, their influence on our lives in another direction is
also very great, as difficult to estimate perhaps, as that of flowers.
Who can doubt that these little brothers of the air are one of the most
civilizing and elevating factors in man's daily life? Their song, their
flight, their thousand and one charming or entertaining habits, their
strong expression of personality, their poetical and mysterious comings
and goings, appeal powerfully to the higher imagination.
The migration of birds is alone enough to fill the mind with enchanting
dreams. To know that every night in late summer and in autumn there is a
stream of birds moving high in the air along the line of the sea-coast
and of the great valleys is enough to awaken fancy. This winged
procession moving along its aerial highway is made of the small and
timid birds that dare not fly by day for fear of hawks and other
enemies; they may be as high as three miles above the surface of the
earth, their height being estimated by watching them through the
telescope as they cross the surface of the moon. Imagine looking through
the telescope at the face of the full moon some night and seeing an
endless procession of little birds speeding across its shining face!
The amazing power of birds to see and hear, and, most interesting of
all, their nest-building habits are calculated to arouse the wonder and
admiration of every observer. What child would not watch with intense
interest the bringing of the straws or other materials, and the deft
weaving of them into the home which is presently to receive the precious
eggs? Even the city sparrow may here be a boon to the mother.
Sufficiently encouraged, it will accommodatingly build almost anywhere.
The child who knows the story of fish life and frog life will need
little telling here, and that is one argument in favor of taking all the
gradual steps from flower to bird. By this time the main ideas are
firmly lodged, the child will readily draw his own conclusions as to the
rest; but there are one or two facts connected with the origin of the
bird which are of great value in fixing the idea of _necessity_ which is
at the foundation of all reproductive phenomena. Everything is as it is
because it is necessary that it should be so. In the frog the higher
development made necessary greater economy in the production of the egg
and the fertilizing cell, and this economy of material necessitated the
more certain fertilization of the egg.
In the bird a great step upwards has been taken. Here we have something
much more complex in every way. The frog was cold-blooded, comparatively
sluggish, and comparatively simple in structure. The bird is
warm-blooded, intensely active, and very much more complex both in
bodily structure and in mind development. Here the reproductive activity
is yet more economically conducted, and instead of thirty or more eggs,
the bird produces often not more than six in a season, and even a
smaller number if it is single-brooded, some eagles, for instance,
rearing only two young in a season. Naturally these few eggs must be
very carefully protected. Since they are not laid in the yielding medium
of water, they cannot have so soft a covering as the eggs of the fish or
frog, but are enclosed in a hard shell. This shell must of course be
formed before the egg is laid, and the egg must be fertilized before
the hard shell encloses it and thus makes forever impossible the
entrance of the fertilizing cell.
The ovaries of the bird are in the small of the back close to the
backbone, and there is a tube called the oviduct or egg-duct, leading
from the ovary down to the lower end of the intestine, which it enters.
There is no separate opening for the oviduct into the outer world.
There are two ovaries, with their oviducts, in the young bird, but these
are so small that it is very difficult indeed to find them. As the bird
approaches maturity, one ovary and its oviduct enlarge, and the ova,
which develop from the inside of the ovary just as the ovule develops
inside the flower ovary, also become large. Although the bird is born
with two ovaries, but one, usually, develops, generally the one on the
left side.
When the bird comes to maturity, there is born in it a yearning for home
and offspring. As the eggs develop, the bird turns to the nest and to
the mate who is to share with her all this beautiful life. When the mate
has been chosen, both prepare the nest to receive the eggs, which will
soon be ready. It is during this period that the fertilizing fluid is
placed in the lower end of the egg-duct, whence the fertilizing cells,
by their power of motion, quickly make their way to the egg, which has
just begun its journey down the oviduct and is as yet without a shell.
The shell-less egg is well known to most country children, as hens often
lay one; and this will always happen where there is not lime enough in
the food of the poultry.
After the egg is fertilized it continues its slow journey down the
oviduct, which enlarges to accommodate it. At first the egg consists of
the yolk alone. This grows to its full size before it leaves the ovary.
The yolk in short _is_ the egg. But there is not enough food material in
it for the development of the bird, so as it passes down the egg-duct it
becomes coated by the so-called "white" of the egg, which is a substance
secreted from the lining of the egg-duct and is not alive, as is a
certain part of the yolk. It is merely stored-up food like that in the
morning-glory seed, for this egg is the seed of the bird. At the lower
end of the egg-duct there is secreted a limy liquid which covers the
shell-less egg and hardens, making the shell. So finally the fertilized
egg has its shell and is ready to be laid. When this time comes, the
bird seeks her nest, and the egg is laid or born, and lies warm and
living, like a jewel in the nest.
It is hardly necessary to add that the fertilizing cells in the male
bird have an origin similar to that of the ova. The testicles and their
ducts are too small to be easily seen in the young bird and in the
winter-time, but can be seen during reproductive activity. The male bird
can usually be told from the female by differences in color and plumage,
but where this is not the case the two sexes cannot be told apart
without actually killing and dissecting the birds, so very simple are
the generative organs.
The ripening of the reproductive elements in the bird occurs in the
spring of the year, and is always with a few exceptions accompanied by
the instinct of nest-making. The birds instinctively and joyfully
prepare the home for their young at this time, both parents joining to
make the pretty structure. With the child the higher emotions which
always accompany reproductive activity in the bird life should be kept
ever prominent,--the affection between the parents, their care and love
for each other, the care and love for the helpless young, their
happiness in this duty as shown in their song and bright colors. Unlike
the fish and the frog, the bird cannot develop unless the egg is kept
warm, and after it hatches the young bird cannot take care of itself for
several weeks. It must be carefully nurtured, and finally even taught
how to fly and find its food.
The maternal hen can be a treasure to the mother seeking to impress the
lesson of love and care; the only defect is the indifference of the
father, which is in marked contrast to the interest shown by other
birds, though there are many proofs that the cock is not without
parental love, as where young chicks have been abandoned he has been
known to rear them.
The love of both the birds for their helpless young, and their devotion
to each other, can be impressed on the young mind in many a picture of
beauty. Many birds pair for life, returning to the same nest year after
year. Nor should the instruction fail to impress upon the young mind the
advance of love and tenderness on the parent for the offspring as we
ascend the scale of life. The flowers, the fishes, the frogs, entrust
their offspring to the care of Mother Nature; the birds cannot do this.
The mother and the father of the helpless little creatures take deep joy
in sacrificing their own freedom and strength and time to this loving
duty. A bird will even lose its life for its young, trying to drive off
an enemy; and every one knows how dangerous it is to approach the nest
of any large bird, eagles and even cranes sometimes killing men and boys
who try to rob them of their young.
The plumage of birds is a pretty subject of study. The wonderful way in
which feathers are adapted to their use, in keeping the bird warm
without greatly increasing its weight or impeding its flight, may be
made very interesting; also their beauty both of structure and color,
and the fact that at maturity the plumage often undergoes remarkable
changes. Young birds are colored like the mother. The brilliant male of
the Baltimore oriole gets his bright dress at maturity, but until that
time he is as soberly clad as his quiet little mother.
The inheritance of the young bird from its father should be enlarged
upon. At the beginning, though the male birds resemble the mother in
appearance, at maturity they wake up to the characteristics of their
father. Then the brilliant colors begin to play over their feathers--his
colors. Then the song trembles from their throats--his song; and the
beautiful creatures might sing as their wonderful wings flash through
the air, "All this loveliness I owe to my father: it is from him I
received this glorious heritage of beauty and song."
The child can learn the terrible consequences to the birds of their
feathers being taken as ornaments by human beings. The children can be
told that the plumage is most beautiful at the mating and nesting
season, and that thousands of birds, both male and female, are slain
then, that the eggs and young birds consequently die, and that some
species have been almost if not quite exterminated in this cruel way.
The Audubon societies are organized for the purpose of instructing young
people about the birds and getting their cooperation in opposing this
needless slaughter. Some of these organizations are extremely
interesting in their field and lecture work on birds; every neighborhood
could have its Audubon society, to the great pleasure and profit of the
members as well as to the profit of the birds.
Where the mother desires to pass directly from the flower to the bird,
this can be well done by comparing the two, so far as their generative
processes are concerned, at every step. She can remind the little one of
how the flower seed is treasured in the ovary until it is able to go out
into the big world, and can then tell him that the wonderful seed of the
bird, which we call the egg, is treasured in the same way; this to be
followed by the story of the care needed by the bird's egg after it is
born,--how it cannot be left to shift for itself, but must be watched
over and kept warm by its loving little parents until it is fit to leave
the shell, how it then breaks its prison and comes forth so weak and
helpless to be yet further loved and cared for and taught by its
faithful parents.
The question is often asked, should not the story of motherhood precede
that of fatherhood in all this early teaching? Up to a certain point it
may be well, and the story of the life and development of the egg can be
told to young children, with the father-bird merely an aesthetic factor,
so to speak. His care of the young, and protection of the mother-bird
can be dilated upon without going any farther. This is a course,
however, which it will not be wise to follow too long, particularly with
boys, whose interest will be greater when they know that the father too
has a vital interest in the life of his offspring. Moreover, there is a
certain spiritual value in connecting the equal need and responsibility
of both parents in the creation of their offspring. The child then
knows that he has the whole truth, and half truths are never quite
safe.
If the child knows the story of flower, fish, and frog life, he will
draw his own conclusions about the birds, and it will be wiser frankly
to tell him this part of the story. If he knows nothing of the earlier
work, and the mother begins with the young birds in the nest, according
to his age and surroundings he should be told more or less, the mother
always remembering that if she defers too long somebody may anticipate
her with the kind of information she particularly desires to avoid.
Another question often asked concerning the bird is, "Would the egg be
laid if it were not fertilized?" It might be or it might not. In all
forms of life the sensitive reproductive system responds with peculiar
readiness to its environment. In birds if it does not receive the
stimulus that comes from mating, the ova may not develop at all, but
remain small and attached to the ovary. Or, a few may be completed and
laid, as is often seen in the case of caged female canaries. But these
eggs of course could never hatch. They are perfect so far as the ovum
is concerned, but lacking fertilization they cannot continue their
development.
Another question often asked, and of peculiar meaning, is, "If the
reproductive system be not exercised, will it not perish for lack of
exercise?" The latest word of science on this subject is that it will
not, either in the bird or elsewhere. In a healthy organism it can
safely remain inoperative with the certainty of becoming active at a
later period if then it receive the normal stimulus.
The lessons to be learned from the birds are many. From them can be
answered all questions, for now we have passed that most difficult of
all points, the relation of father to child in the animal world, and
everything else can be explained through the knowledge already gained.
The well-taught child will recognize the justice and necessity for the
existing processes of life. He will realize their deep meaning, their
far-reaching influence, and their tremendous importance in preserving
upon the earth the multitudes of living forms that inhabit it.
The flower and the bird are the two most important helps in imparting
the facts concerning the renewal of life throughout nature.
XI
THE MAMMAL
The mother who has conducted the child through the various life forms up
to the mammal will not be likely to wish to stop there. Having gone thus
far, it will be easy to continue and reveal to the child the wonderful
life that yet remains.