Curiosities of Animal Life [pp. 232-239]

Curiosities of Animal Life.
new one will grow; and crabs, lob sters, spiders, etc., are known to re place their amputated limbs. The
instances we now and then meet with
of what are called monsters-two headed dogs, calves with six legs, and,
more rarely, even double-headed hu man beings, are examples of the phe nomenon of budding-which is very
common, by the way, among fishes;
and these is an animalcule called the
amoeba which shows a more remarklable tenacity of life than any of the
other creatures we have mentioned,
since you may divide and subdivide it
until it is physically impossible to reduce it to particles any smaller,
and yet each piece will live.
o
The discovery that animals may
originate in so many ways independent of maternal gestation naturally
suggests the inquiry whether further
researches may not develop still
other methods of reproduction, in
which the new-born creature shall
have no connection whatever with any
previously existing individual. Thus
we are brought back to the question
which was thought to have been settled long ago, whether generation ever
takes plate spontaneously, as Aristotle and the old physicists supposed
it did. Later naturalists, following the
Italian, Redi, utterly rejected the supposition; but within the present century it has found many reputable supportels, and Professor Clark is oneof them.
When organic matter decays, numbers
of infusoria, or microscopic plants
and animals, arise in it. Where do
they come from? Do the disorganized particles, set free by the process
of decomposition, combine into new
forms, which are then endowed with
life by the direct action of Almighty
power; or is the decaying substance
merely the nest in which minute eggs
or seeds, borne thither upon the air,
or dropped by insects, find conditions
suitable for their development in the
ordinary natural way? The question
is not easily answered. Many of
these germs are so excessively minute
as to defy detection. Some of the in fusoria are no larger than the twefity four-thousandth of an inch in diame ter, and it is estimated that a drop of
water might contain five hundred mil lions of them. It is obvious that the
germs of such little creatures must be
invisible even with the best micro scope. The problem can only be
solved by placing a portion of the
decomposing matter under such condi tions that any germs it may contain
shall infallibly be killed and that none
can possibly reach it; then, if infusoria appear, we shall know that they
have been generated spontaneously.
The great difficulty is in securing
these conditions. For the development of the living forms we require
both water and air. How are we to
be certain that there are no living
germs in the organic matter before we
begin the experiment? that there are
none in the water? that none are
brought by the lair? The action of
heat has been relied upon for the destruction of germs in the organic matter and the water, and it has been
sought to purify the air from them by
passing it through sulphuric acid;
but experience has shown that sulphuric acid does not, kill the germs;
so of course experiments performed in
that way prove nothing. Professor
Clark quotes a series of very delicate
experiments tried by Professor Jeffries Wyman, of Harvard University,
which seem to us to come nearer to
proving spontaneous generation than
any others with which we are acquainted. HIHe proceeded in three
different methods, as follows:
1. The organic matter, consisting
of a solution of beef or mutton juice
(or, in a fews instances, vegetable matter), was placed in a flask fitted with
a cork through which passed a glass
tube. The cork was pushed deeply into
the mouth of the flask, and the space
above it was filled with an adhesive
cement, composed of resin, wax, and
varnish. The tube was drawn to a
narrow neck a little way above the
cork, and bent at right angles, and
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