Darwiniana | Page 6

of the
naturalist's mind. Darwin's theory brings us the other way to the same
result. In his view, not only all the individuals of a species are

descendants of a common parent, but of all the related species also.
Affinity, relationship, all the terms which naturalists use figuratively to
express an underived, unexplained resemblance among species, have a
literal meaning upon Darwin's system, which they little suspected,
namely, that of inheritance. Varieties are the latest offshoots of the
genealogical tree in "an unlineal" order; species, those of an earlier date,
but of no definite distinction; genera, more ancient species, and so on.
The human races, upon this view, likewise may or may not be species
according to the notions of each naturalist as to what differences are
specific; but, if not species already, those races that last long enough
are sure to become so. It is only a question of time.
How well the simile of a genealogical tree illustrates the main ideas of
Darwin's theory the following extract from the summary of the fourth
chapter shows:
"It is a truly wonderful fact--the wonder of which we are apt to
overlook from familiarity--that all animals and all plants throughout all
time and space should be related to each other in group subordinate to
group, in the manner which we everywhere behold--namely, varieties
of the same species most closely related together, species of the same
genus less closely and unequally related together, forming sections and
sub-genera, species of distinct genera much less closely related, and
genera related in different degrees, forming sub-families, families,
orders, sub-classes, and classes. The several subordinate groups in any
class cannot be ranked in a single file, but seem rather to be clustered
round points, and these round other points, and so on in almost endless
cycles. On the view that each species has been independently created, I
can see no explanation of this great fact in the classification of all
organic beings; but, to the best of my judgment, it is explained through
inheritance and the complex action of natural selection, entailing
extinction and divergence of character, as we have seen illustrated in
the diagram.
"The affinities of all the beings of the same class have sometimes been
represented by a great tree. I believe this simile largely speaks the truth.
The green and budding twigs may represent existing species; and those
produced during each former year may represent the long succession of
extinct species. At each period of growth all the growing twigs have
tried to branch out on all sides, and overtop and kill the surrounding

twigs and branches, in the same manner as species and groups of
species have tried to overmaster other species in the great battle for life.
The limbs divided into great branches, and these into lesser and lesser
branches, were themselves once, when the tree was small, budding
twigs; and this connection of the former and present buds by ramifying
branches may well represent the classification of all extinct and living
species in groups subordinate to groups. Of the many twigs which
flourished when the tree was a mere bush, only two or three, now
grown into great branches, yet survive and bear all the other branches;
so with the species which lived during long-past geological periods,
very few now have living and modified descendants. From the first
growth of the tree, many a limb and branch has decayed and dropped
off; and these lost branches of various sizes may represent those whole
orders, families, and genera, which have now no living representatives,
and which are known to us only from having been found in a fossil
state. As we here and there see a thin, straggling branch springing from
a fork low down in a tree, and which by some chance has been favored
and is still alive on its summit, so we occasionally see an animal like
the Ornithorhynchus or Lepidosiren, which in some small degree
connects by its affinities two large branches of life, and which has
apparently been saved from fatal competition by having inhabited a
protected station. As buds give rise by growth to fresh buds, and these,
if vigorous, branch out and overtop on all sides many a feebler branch,
so by generation I believe it has been with the great Tree of Life, which
fills with its dead and broken branches the crust of the earth, and covers
the surface with its ever-branching and beautiful ramification."
It may also be noted that there is a significant correspondence between
the rival theories as to the main facts employed. Apparently every
capital fact in the one view is a capital fact in the other. The difference
is in the interpretation. To run the parallel ready made to our hands:
[I-4]
"The simultaneous existence of the most