t many years since, it was held as certain that
the chemical compounds distinguished as organic could not be formed
artificially. Now, more than a thousand organic compounds have been
formed artificially. Chemists have discovered the art of building them
up from the simpler to the more complex, and do not doubt that they will
eventually produce the most complex. Moreover, the phenomena attending
isomeric change give a clue to those movements which are the only
indications we have of life in its lowest forms. In various colloidal
substances, including the albuminoid, isomeric change is accompanied by
contraction or expansion, and consequent motion; and, in such primordial
types as the _Protogenes_ of Haeckel, which do not differ in appearance
from minute portions of albumen, the observed motions are comprehensible
as accompanying isomeric changes caused by variations in surrounding
physical actions. The probability of this interpretation will be seen on
remembering the evidence we have that, in the higher organisms, many
functions are essentially effected by isomeric changes from one to
another of the multitudinous forms which protein assumes.

Thus the reply to this objection is, first, that there is going on from
both sides a narrowing of the chasm supposed to be impassable; and,
secondly, that, even were the chasm not in course of being filled up, we
should no more be justified in therefore assuming a supernatural
commencement of life, than Kepler was justified in assuming that there
were guiding-spirits to keep the planets in their orbits, because he
could not see how else they were to be kept in their orbits.

* * * * *

The third definite objection made by Mr. Martineau is of kindred nature.
The Hypothesis of Evolution is, he thinks, met by the insurmountable
difficulty that plant life and animal life are absolutely distinct. "You
cannot," he says, "take a single step toward the deduction of sensation
and thought: neither at the upper limit do the highest plants (the
exogens) transcend themselves and overbalance into animal existence; nor
at the lower, grope as you may among the sea-weeds and sponges, can you
persuade the sporules of the one to develop into the other."

This is an extremely unfortunate objection to raise. For, though there
are no transitions from vegetal to animal life at the places Mr.
Martineau names, where, indeed, no biologist would look for them; yet
the conne