THE PROGRESS OF DISCOVERY
We find it hard to realise that not so very long ago the steam-engine
and the electric telegraph were unknown; and we are right when we say
that life must have worn a very different aspect in those days. It is
scarcely less difficult for us to realise the change that has been
wrought in men's thoughts since the time when the biological cell was
unrecognised, and the theory of evolution had not yet been formulated.
The rapidity with which advances of knowledge were made in the physical
sphere was astonishing, and it was only to be expected that they should
have seemed not a little bewildering. We must try to note the main
steps of the movement, giving the names of some of the representative
workers and thinkers.
It is generally agreed that the foundations of modern chemistry were
laid by Dalton (1808). He it was who revived the old atomic theory,
and determined the weights of the atoms and the {22} proportions in
which they are combined into molecules--the smallest particles which
could exist in a free condition. By so doing he prepared the way for
the subsequent researches of Faraday and Clerk-Maxwell into the
properties of electricity and magnetism, and for the investigations by
Helmholtz and others into the connexion between electric attraction and
chemical affinities.
The forerunner of the wonderful advances of modern biology was the
French naturalist Lamarck (1809), who, in opposition to the accepted
doctrine of separate creations, suggested that all the species of
living creatures, not excepting the human, have arisen from older
species in the course of long periods of time. The common parent forms
he held to have been simple and lowly organisms, and he accounted for
the gradual differentiation of types by the hypothesis that they were
the results of the inheritance of characteristics which had been
acquired by continued use--as, for example, in the case of the giraffe
who was supposed to have owed the length of its neck to the efforts of
its ancestors to browse upon trees that were just beyond their reach.
He maintained that the changes produced in the parents by temperature,
nutrition, repeated use or disuse, were inherited so that they
reappeared in their offspring. But the evidence adduced was {23}
judged to be insufficient, and the balance of scientific opinion was
decidedly against his views.
Lyell (1830) gave a new direction to the science of geology by
accumulating evidence to prove the certainty of a natural and
continuous development in the formation of the crust of the earth, thus
opposing the catastrophic idea which had previously prevailed. One
outcome of his researches was to make it plain that the history of this
development must have extended over enormous tracts of time.
More revolutionary still in its effects was the epoch-making discovery
of the protoplasmic cell as the common element of life in the plant and
animal world, made by the Germans Schleiden and Schwann (1838). It was
this that first bridged over what were held to be the fundamental
distinctions of animate nature, and made possible the conception of a
vital physical continuity which has since been accepted as an axiom of
biological science.
By Joule's great discovery (1840) that the same amount of work, whether
mechanical or electrical, and however expended, always produced exactly
the same amount of heat--that, in effect, heat and work were equivalent
and interchangeable--the way was opened to the conclusion that the
total energy of the material universe is constant in amount through all
its changes.
{24}
A theory to account for the black lines crossing the coloured band of
light, or spectrum, which is obtained by passing sunlight through a
glass prism, originally suggested by Sir George Stokes, and
subsequently reintroduced and verified by the German chemists, Bunsen
and Kirchhoff, led to the important discovery that the sun and the
stars are constituted of the very same elements as those of the earth
beneath our feet. Spectrum analysis, moreover, soon detected new
elements, _e.g._, helium, so-called because first observed as existing
in the sun.
But great and stimulating as these discoveries were, their effect upon
the thought of the age was not to be compared with that which was to be
exercised by a theory which, starting in the domain of biological
science, soon passed on to far more extended applications. The theory
took its rise from a suggestion made in two papers, by Charles Darwin
and Alfred Russel Wallace, which were read before the Linnean Society
on July 1st, 1858.
The Darwinian theory--for so it was soon named--undertook to explain
the formation of species by the principle of natural selection through
the survival of the fittest in the struggle for life.[1] {25} Darwin
started from the admitted achievements of artificial selection; from
the results attained by nurserymen and cattle breeders, who, by
selecting the kinds they wished to perpetuate, had been able to vary
and improve their stocks. He conceived that a like process had been
carried on by Nature through vast spaces of time, and that it was this
picking, choosing, continuing and abandoning of traits and qualities
which had resulted in the preservation of the types which it had been
best to retain--the reason in all cases being the fitness to correspond
effectively to the conditions prescribed by environment.
It is important to remember that Darwin never claimed that his doctrine
of evolution could account for the occurrence of variations. That it
could do so he expressly denied. "Some," he said, in his great work,
_The Origin of Species_ (1859) "have, even imagined that natural
selection induces variability, whereas it implies only the preservation
of such variations as arise.... Unless such occur, natural selection
can do nothing." What he saw, and proved by an amazing wealth of
illustrative facts, was that any variation in structure or character
which gave to an organism ever so slight an advantage might determine
whether or not it would survive amid the fierce competition around it,
and whether {26} it would obtain a mate and produce offspring. He
shewed that all innate variations (which are to be distinguished from
the acquired characteristics upon the inheritance of which Lamarck had
depended) tend to be transmitted, so that in this manner a favourable
variation might be perpetuated, and in time a new species be developed.
Simple as this account of the matter sounds when once it has been
clearly stated, the discovery--for such it was--opened an entirely new
chapter in the history of science, inasmuch as it completely
revolutionised the conceptions which had previously been entertained
with regard to the relationships and the progress of all living things.
It was Darwinism, accordingly, that provided the principal subject of
the controversy which was waged between the upholders and the
assailants of the older opinions during the latter half of the
nineteenth century.
[1] The actual phrase "Survival of the fittest" was Herbert Spencer's.
Darwin had spoken of "The preservation of favoured races."
{27}