id="pgepubid00013">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 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 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.

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] 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 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."

CHAPTER III

THEOLOGICAL DIFFICULTIES

We shall not exaggerate if we say that the chief interest aroused by these discoveries