cing our own remarks on this subject by quoting them.[A] In order
to determine, he says, whether an organic form, an organ, or an
organism, belongs to the same series of development as another, or
that which is the same is developed from it, or _vice versa_, there is
only one way, viz., to observe how the second grows out of the first.
We see the commencement of the second begin as a part of the first,
perfect itself in connection with it, and at last it often becomes
independent; but be it through spontaneous dismembering from the
first, or that the latter be destroyed and the second remains, both
their disunited bodies are always connected together in organic
continuity, as parts of a whole (single one) that can cease earlier or
later.

By observing the organic continuity, we know that the apple is the
product of development of an apple-tree, and not hung on it by
chance, that the pip of an apple is a product of the development of
the apple, and that from the pip an apple-tree can at last be
developed, that therewith all these bodies are members of a sphere of
development or form. It is the same with every similar experience of
our daily life, that where an apple-tree stands, many apples lie on
the ground, or that in the place where apple-pips are sown seedlings,
little apple-trees, grow out of the ground, is not important to our
view of the course of development. Every one recognizes that in his
daily life, because he laughs at a person who thinks a plum which
lies under an apple-tree has grown on it, or that the weeds which
appear among the apple seedlings come from apple-pips. If the
apple-tree with its fruit and seed were microscopically small, it
would not make the difference of a hair's breadth in the form of the
question or the method of answering it, as the size of the object
can be of no importance to the latter, and the questions which
apply to microscopical fungi are to be treated in the same manner.

If it then be asserted that two or several forms belong to a series of
development of one kind, it can only be based on the fact of their
organic continuity. The proof is more difficult than in large plants,
partly because of the delicacy, minuteness, and fragility of the
single parts, particularly the greater part of the mycelia, partly
because of the resemblance of the latter in different species, and
therefore follows the danger of confusing them with different kinds,
and finally, partly in consequence of