Maitland, Government Geologist, who apologised for the unavoidable absence
of the acting-president of the Museum committee (Mr. Justice McMillan).
The lecture was illustrated by a number of limelight views.

At the outset Dr. Blackburne dealt with what he called “the evolution of
the evolution theory,” and the work of Darwin. Proceeding, he said, inter
alia :—“Animals (including, of course, human beings) are divided, roughly,
into two great classes, vertebrate and invertebrate, and for shortness I
will confine my attention to the vertebrates, which include such different
species as snakes, fishes, the large animals, and man. Now all these
vertebrates are formed on exactly the same plan. Although these creatures
live in such different ways, it is obvious that the structures of their
limbs are all modifications of the same plan. It is, however, with regard
to the brain that we are apt to think we are something quite apart from
other creatures, but even here one can take the different structures of
the brain, and show just as in the case of the bones of the limb that the
same principal parts exist throughout all the different species. A
photograph or other reproduction of a human brain looks different from
that of one of the lower animals such as a bird, but that is merely
because one particular part, the forebrain, is so much more highly
developed relatively to the other parts in his [sic] case, though it still
exists in the lower animal. In the latter the various parts look more
distinct, in man one particular part is so developed as to quite
overshadow all the rest, though these others still exist, and are easily
found on dissection. It is just the same as the case of the one highly
developed digit you saw in the foot of the horse which quite overshadows
the rest, and the brain is made up of the same essential separate parts in
the two instances of man and the lower animal. Also a perfect graduation
of brains could be shown in which the larger development of this
particular part relatively to the other parts could be shown to occur in
regular gradations as we ascend the scale from the very lowest vertebrates
up to man. Now we could go over all the different structures of the body,
the various bones, the nervous system, the heart, alimentary canal, etc.,
and show in every case this similarity in general plan with modifications
to suit the different species. So much for the general homological
structure of animals. It could of course, and has been, learnedly argued
that these homological structures can be fully explained on mechanical
grounds, but this, to my mind, simply begs the question, for, as Darwin
points out, it is naturally just the best mechanically adapted organs that
would be evolved by means of natural selection. Now let us see if we can
find anything in the structure of, say, man, which can be regarded as
further and more direct evidence. It is well-known that many animals,
especially cattle, have a highly developed power of moving or twitching
the skin. This movement is performed by a well-developed layer of muscle
situated just underneath the skin. Man does not require a muscle of this
sort, and yet he has rudiments of it, especially about the face, where a
part of it is still in use for lifting the eyebrows. There is another
remnant of it in the neck and some about the ears, but most peculiar of
all remnants are sometimes found in various queer places, about the
armpits, near the shoulder blades, etc. One may be surprised to hear that
the whole of our external ear is merely a rudiment consisting of the
cartilages, etc., which in the lower animals support their larger and more
useful outer ear, and careful observation and experiment have shown that
our external ear is of little, if any, distinct use at all. Again, if the
ear has been developed in the way suggested, the helix, or outer curve, is
obviously just the outer rim curled inwards. Now most people can observe a
small point or projection on the inner side of this helix, just where the
tip of a pointed and erect ear would lie if the edge of it were turned
inwards. We know that some animals have a third eyelid. We have only two,
but we have a remnant at the inner angle of the eye, which is the vestige
of this eyelid, and is called the semi-lunar fold. Fibres of muscle have
actually been found in this rudimentary fold of ours. Now there is yet
another series of facts which can be considered evidence of evolution,
namely, those facts derived from geological investigations and the study
of fossil remains. I have already referred to the fact that certain
rudiments in human beings which seem to have a relation to structures
found in animals were more frequently found in ancient human remains than
they are in the present day. Evidently they are being dropped by a gradual
process of evolution. But I will take one rather striking instance which
refers to the evolution of the horse. The prehistoric ancestor of this
creature seems to have been a smaller animal than its descendant, and with
the usual multiple toes as we see in the first of this series. Gradually,
however, the force of circumstances was evidently such that individuals
which tended to have a foot better adapted for certain other qualities
tended to become predominant, and this pressure of circumstances
continuing throughout the ages brought about the changes you see here. I
might at this point take the opportunity of impressing you with the great
time which is required for these changes, stretches of time probably which
our very finite intelligence could hardly realise like the distances
between the heavenly bodies. These evolutionary changes are always very
gradual, never sudden, or cataclysmal.”

In conclusion, the lecturer quoted Darwin’s own summary of the subject as
it appeared to him :—“ By considering the embryological structure of man,
the homologies which he presents with the lower animals, the rudiments
which he retains, and the reversions to which he is liable, we can partly
recall in imagination the former condition of our early progenitors, and
can approximately place them in their proper place in the zoological
series. We thus learn that man is descended from a hairy-tailed quadruped,
probably arboreal in its habits, and an inhabitant of the Old World. This
creature, if its whole structure had been examined by a naturalist, would
have been classed among the quadrumana, as surely as the still more
ancient progenitor of the Old and the New World monkeys. The quadrumana
and all the higher mammals are probably derived from an ancient marsupial
animal, and this through a long line of diversified forms, from some
amphibian-like creature, and this again from some fish-like animal. In the
dim obscurity of the past we can see that the early progenitor of all the
vertebrata must have been an aquatic animal provided with branchiae, with
the two sexes united in the same individual, and with the most important
organs of the body (such as the brain and heart), imperfectly, or not at
all, developed. This animal seems to have been more like the larvae of the
existing marine Ascidians than any other known form.”

A discussion followed the reading of the paper, and Dr. Blackburne was
accorded a cordial vote of thanks