f time required for rapidly multiplying
increase of structural differences.--Proboscis monkey.--Time required
for deposition of strata necessary for Darwinian evolution.--High
organization of Silurian forms of life.--Absence of fossils in oldest
rocks.--Summary and conclusion.

Two considerations present themselves with regard to the necessary relation
of species to time if the theory of "Natural Selection" is valid and
sufficient.

The first is with regard to the evidences of the past existence of
intermediate form, their duration and succession.

The second is with regard to the total amount of time required for the
evolution of all organic forms from a few original ones, and the bearing of
other sciences on this question of time.

As to the first consideration, evidence is as yet against the modification
of species by "Natural Selection" alone, because not only are minutely
transitional forms generally absent, but they are absent in cases where we
might certainly _a priori_ have expected them to be present. [Page 129]

Now it has been said:[125] "If Mr. Darwin's theory be true, the number of
varieties differing one from another a very little must have been
indefinitely great, so great indeed as probably far to exceed the number of
individuals which have existed of any one variety. If this be true, it
would be more probable that no two specimens preserved as fossils should be
of one variety than that we should find a great many specimens collected
from a very few varieties, provided, of course, the chances of preservation
are equal for all individuals." "It is really strange that vast numbers of
perfectly similar specimens should be found, the chances against their
perpetuation as fossils are so great; but it is also very strange that the
specimens should be so exactly alike as they are, if, in fact, they came
and vanished by a gradual change."

Mr. Darwin attempts[126] to show cause why we should believe _a priori_
that intermediate varieties would exist in lesser numbers than the more
extreme forms; but though they would doubtless do so sometimes, it seems
too much to assert that they would do so generally, still less universally.
Now little less than universal and very marked inferiority in numbers would
account for the absence of certain series of minutely intermediate fossil
specimens. The mass of palaeontological evidence is indeed overwhelmingly
against minute and gradual modification. It i