inviolate.  Each individual repeats exactly
its parent form, passes through the same
transitions, from one stage of development
to another, runs the same course, attains to
about the same size, lives to about the same
age: then, having in its turn, transmitted
to other individuals the same unchangeable
germ-power, dies.

  One of the best known instances of the
almost unextinguishable vitality of germ-power
is witnessed in the Hydra viridis.  It
would almost seem that any little bit that
has once been alive, has the power of reproducing
a perfect animal.  Trembley, the
naturalist, cut a hydra into four pieces.
Each became a perfect hydra.  He cut up
these, while they were growing, with the
same result, until from one hydra he had
obtained fifty, all complete, and all capable of
multiplying by gemmation in the natural
way.  But more extraordinary still was the
result of splitting one into seven parts, leaving
them connected by the tail.  The hydra
became seven-headed, and Trembley saw them
all eating at the same time.  He cut off the
seven heads, and, hydra-like, they sprang
forth again.  " Even the fabulist dared not
invent such a prodigy as the naturalist now
saw.  The heads of the Lernæan hydra
perished after excision, the heads of this hydra
grew for themselves bodies, and multiplied
with as much vigour as their parent trunk."

  Probably this power of reproducing a
perfect animal from a small part of one is
one of the methods by which creatures
so endowed preserve their race from being
destroyed by the animals who feed upon
them.  When one of the brittle star-fishes
breaks itself to pieces, it disappoints the
naturalist who is seeking for specimens.  But
nothing can be more satisfactory to a creature
about to be devoured by a ravenous
enemy, than to break off a little bit for him,
and then spring up again, not one individual,
but a dozen.

  This power of multiplication is confined to
those creatures whose structure is comparatively
very simple.  In the higher forms the
germ-power is expended in the development,
In man it is only equal to the preservation
of the integrity of the body, and
not to the reproduction of any large part
that may be lost.  But the process of repair
illustrates very beautifully the manner in
which the germ-power communicates, to
every particle of matter, its own characteristic
life.  In the healing of a large open
wound, the first step is the effusion of a semi-fluid
substance, consisting of layers of minute
cells, from which are to be produced granulations;
that is, small round projections which
grow up to replace the loss of substance which
the disease has occasioned.  To form these,
it is necessary that blood-vessels should be
sent into the cellular substance, which are
thus formed.  On the side of a blood-vessel
lying under the cells, a small swelling or
pouch is observed to protrude, which gradually
elongates itself in a curved direction.
A little further on, a similar pouch is seen,
which also elongates itself, and directs its
course unerringly to meet its fellow.  At the
crown of the arch they unite, the partition
wall at their closed ends clears away, and
a perfect arched tube is formed, through
which the blood flows.  From the crown of
two adjacent arches similar outgrowing
pouches arise, converge, unite; and in this
way granulations are supplied with blood.
The wonder of this process is: how, in a
day, a hundred or more of these fine loops
of membranous tube less than 1/1000 of an
inch in diameter, should be upraised, not
by any force of pressure, but each by a
living growth and development.

  Suppose one of these outgrowing blood-vessels
should be injured and should burst.
The minute blood-globules will escape and lie
in a confused mass! But only for a short
time.  These little globules of blood are
alive; and, by their own indwelling energy
they will arrange themselves in the line
which the vessel should have taken, channeling
out a way for themselves, through the
granulation cells, until a membraneous wall
is formed around them, and the arch is completed
as before.  We see, in this instance, a
characteristic of the animated germ, that it is
diffused through many parts, causing them
to concur in the right time and measure to
the attainment of the perfect design.  An
animal is not developed as a tree grows;
but all the parts—the blood and the vessels in
which it is to flow, the nerves and muscles, as
well as the different limbs of the body—
are being formed at the same time; creative
energy presiding over every part, and causing
them all to combine in one harmonious development.

  In the repair of injuries, not only is the
loss supplied by the right material, but the
new tissue is always of the same age as that
which it replaces.  The skin of an adult will
not be replaced by the delicate skin of an
infant.  In the reproduction of the foot of a
lizard, it grows at once into the full dimensions
of the part, according to the age of the
animal.  And Spallanzani mentions that when
a salamander's leg is removed, the new limb
will be developed in form and structure, like
the larva; but, as to size, it will, from the
beginning, be developed to the full proportions
of the animal.

  As no amount of cultivation, or any combination
of favourable circumstances will ever
do more than produce a perfect individual of
its own species, and never develop it in any
characteristic of a superior class; so, with,
regard to the instincts and dispositions of
animals, the same law prevails.  You may,
indeed, tame one individual of any race, as a
lion or a bear, and make him know his master,
and be gentle and obedient to him.  But,
turn the lion into his native forest again, and