The ancient Phoenicians, Egyptians, Hindus, Japanese, and Greeks all
shared the belief that the whole world was hatched from an egg made by the
Creator. This idea of development is at least true in the case of every
living thing upon the earth to-day; every plant springs from its seed,
every animal from its egg. And still another sweeping, all-inclusive
statement may be made,--every seed or egg at first consists of but one
cell, and by the division of this into many cells, the lichen, violet,
tree, worm, crab, butterfly, fish, frog, or other higher creature is
formed. A little embryology will give a new impetus to our studies,
whether we watch the unfolding leaves of a sunflower, a caterpillar
emerging from its egg, or a chick breaking through its shell.
The very simplest and best way to begin this study is to go to the nearest
pond, where the frogs have been croaking in the evenings. A search among
the dead leaves and water-soaked sticks will reveal a long string of black
beads. These are the eggs of the toad; if, however, the beads are not in
strings, but in irregular masses, then they are frogs' eggs. In any case
take home a tumblerful, place a few, together with the thick, transparent
gelatine, in which they are encased, in a saucer, and examine them
carefully under a good magnifying glass, or, better still, through a
low-power microscope lens.
You will notice that the tiny spheres are not uniformly coloured but that
half is whitish. If the eggs have been recently laid the surface will be
smooth and unmarked, but have patience and watch them for as long a time
as you can spare. Whenever I can get a batch of such eggs, I never grudge
a whole day spent in observing them, for it is seldom that the mysterious
processes of life are so readily watched and followed.
Keep your eye fixed on the little black and white ball of jelly and before
long, gradually and yet with never a halt, a tiny furrow makes its way
across the surface, dividing the egg into equal halves. When it completely
encircles the sphere you may know that you have seen one of the greatest
wonders of the world. The egg which consisted of but one cell is now
divided into two exactly equal parts, of the deepest significance. Of the
latter truth we may judge from the fact that if one of those cells should
be injured, only one-half a polliwog would result,--either a head or a
tail half.
Before long the unseen hand of life ploughs another furrow across the egg,
and we have now four cells. These divide into eight, sixteen, and so on
far beyond human powers of numeration, until the beginnings of all the
organs of the tadpole are formed. While we cannot, of course, follow this
development, we can look at our egg every day and at last see the little
_wiggle heads_ or polliwogs (from _pol_ and _wiggle_) emerge.
In a few days they develop a fin around the tail, and from now on it is an
easy matter to watch the daily growth. There is no greater miracle in the
world than to see one of these aquatic, water-breathing, limbless
creatures transform before your eyes into a terrestrial, four-legged frog
or toad, breathing air like ourselves. The humble polliwog in its
development is significant of far more marvellous facts than the
caterpillar changing into the butterfly, embodying as it does the deepest
poetry and romance of evolution.
Blue dusk, that brings the dewy hours,
Brings thee, of graceless form in sooth.
Edgar Fawcett.