It is now proved that every plant begins its existence under
the same form; that is to say, in that of a cell--a particle of
nitrogenous matter having substantially the same conditions. So that
if you trace back the oak to its first germ, or a man, or a horse, or
lobster, or oyster, or any other animal you choose to name, you shall
find each and all of these commencing their existence in forms
essentially similar to each other: and, furthermore, that the first
processes of growth, and many of the subsequent modifications, are
essentially the same in principle in almost all.
In conclusion, let me, in a few words, recapitulate the positions which
I have laid down. And you must understand that I have not been talking
mere theory; I have been speaking of matters which are as plainly
demonstrable as the commonest propositions of Euclid--of facts that
must form the basis of all speculations and beliefs in Biological
science. We have gradually traced down all organic forms, or, in other
words, we have analyzed the present condition of animated nature, until
we found that each species took its origin in a form similar to that
under which all the others commence their existence.
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