seventeen years previously (from 1645). A little later the Academy of Sciences of Paris was established by Louis XIV. The influence of these great academies of the 17th century on the progress of zoology was precisely to effect that bringing together of the museum-men and the physicians or anatomists which was needed for further development. Whilst the race of collectors and systematizers culminated in the latter part of the 18th century in Linnaeus, a new type of student made its appearance in such men as John Hunter and other anatomists, who, not satisfied with the superficial observations of the popular “zoologists,” set themselves to work to examine anatomically the whole animal kingdom, and to classify its members by aid of the results of such profound study. Under the influence of the touchstone of strict inquiry set on foot by the Royal Society, the marvels of witchcraft, sympathetic powders and other relics of medieval superstition disappeared like a mist before the sun, whilst accurate observations and demonstrations of a host of new wonders accumulated, amongst which were numerous contributions to the anatomy of animals, and none perhaps more noteworthy than the observations, made by the aid of microscopes constructed by himself, of Leeuwenhoek, the Dutch naturalist (1683), some of whose instruments were presented by him to the society.
It was not until the 19th century that the microscope, thus early applied by Leeuwenhoek, Malpighi, Hook and Swammerdam to the study of animal structure, was perfected as an instrument, and accomplished for zoology its final and most important service. The perfecting of the microscope led to a full comprehension of the great doctrine of cell-structure and the establishment of the facts—(1) that all organisms are either single corpuscles (so-called cells) of living material (microscopic animalcules, &c.) or are built up of an immense number of such units; (2) that all organisms begin their individual existence as a single unit or corpuscle of living substance, which multiplies by binary fission, the products growing in size and multiplying similarly by binary fission; and (3) that the life of a multicellular organism is the sum of the activities of the corpuscular units of which it consists, and that the processes of life must be studied in and their explanation obtained from an understanding of the chemical and physical changes which go on in each individual corpuscle or unit of living material or protoplasm.
Meanwhile the astronomical theories of development of the solar system from a gaseous condition to its present form, put forward by Kant and by Laplace, had impressed men’s minds with the conception of a general movement of spontaneous Ideas of development.progress or development in all nature. The science of geology came into existence, and the whole panorama of successive stages of the earth’s history, each with its distinct population of strange animals and plants, unlike those of the present day and simpler in proportion as they recede into the past, was revealed by Cuvier, Agassiz and others. The history of the crust of the earth was explained by Lyell as due to a process of slow development, in order to effect which he called in no cataclysmic agencies, no mysterious forces differing from those operating at the present day. Thus he carried on the narrative of orderly development from the point at which it was left by Kant and Laplace—explaining by reference to the ascertained laws of physics and chemistry the configuration of the earth, its mountains and seas, its igneous and its stratified rocks, just as the astronomers had explained by those same laws the evolution of the sun and planets from diffused gaseous matter of high temperature. The suggestion that living things must also be included in this great development was obvious.
The delay in the establishment of the doctrine of organic evolution was due, not to the ignorant and unobservant, but to the leaders of zoological and botanical science. Knowing the almost endless complexity of organic structures, realizing that man himself with all the mystery of his life and consciousness must be included in any explanation of the origin of living things, they preferred to regard living things as something apart from the rest of nature, specially cared for, specially created by a Divine Being. Thus it was that the so-called “Natur-philosophen”The Natur-philosophen. of the last decade of the 18th century, and their successors in the first quarter of the 19th, found few adherents among the working zoologists and botanists. Lamarck, Treviranus, Erasmus Darwin, Goethe, and Saint-Hilaire preached to deaf ears, for they advanced the theory that living beings had developed by a stow process of transmutation in successive generations from simpler ancestors, and in the beginning from simplest formless matter, without being able to demonstrate any existing mechanical causes by which such development must necessarily be brought about. They were met by the criticism that possibly such a development had taken place; but, as no one could show as a simple fact of observation that it had taken place, nor as a result of legitimate inference that it must have taken place, it was quite as likely that the past and present species of animals and plants had been separately created or individually brought into existence by unknown and inscrutable causes, and (it was held) the truly scientific man would refuse to occupy himself with such fancies, whilst ever continuing to concern himself with the observation and record of indisputable facts. The critics did well; for the “Natur-philosophen,” though right in their main conception, were premature.
It was reserved for Charles Darwin, in the year 1859, to
place the whole theory of organic evolution on a new footing,
and by his discovery of a mechanical cause actually
existing and demonstrable by which organic evolution doctrineDarwin’s doctrine
of organic evolution.
must be brought about, entirely to change the attitude
in regard to it of even the most rigid exponents of
the scientific method. Darwin succeeded in establishing
the doctrine of organic evolution by the introduction
into the web of the zoological and botanical sciences of a new
science. The subject-matter of this new science, or branch of
biological science, had been neglected: it did not form part of
the studies of the collector and systematist, nor was it a branch
of anatomy, nor of the physiology pursued by medical men,
nor again was it included in the field of microscopy and the cell theory. The area of biological knowledge which Darwin was
the first to subject to scientific method and to render, as it were,
contributory to the great stream formed by the union of the
various branches, is that which relates to the breeding of animals
and plants, their congenital variations, and the transmission
and perpetuation of those variations. This branch of biological
science may be called thremmatology (θρἐμμα, “a thing bred”). Outside the scientific world an immense mass of observation
and experiment had grown up in relation to this subject. From
the earliest times the shepherd, the farmer, the horticulturist,
and the “fancier” had for practical purposes made themselves
acquainted with a number of biological laws, and successfully
applied them without exciting more than an occasional notice
from the academic students of biology. It is one of Darwin’s
great merits to have made use of these observations and to have
formulated their results to a large extent as the laws of variation
and heredity. As the breeder selects a congenital variation
which suits his requirements, and by breeding from the animals
(or plants) exhibiting that variation obtains a new breed specially
characterized by that variation, so in nature is there a selection
amongst all the congenital variations of each generation of a
species. This selection depends on the fact that more young
are born than the natural provision of food will support. In
consequence of this excess of births there is a struggle for
existence and a survival of the fittest, and consequently an
ever-present necessarily acting selection, which either maintains
accurately the form of the species from generation to generation
or leads to its modification in correspondence with changes in
the surrounding circumstances which have relation to its fitness
for success in the struggle for life.
Darwin’s introduction of thremmatology into the domain of scientific biology was accompanied by a new and special development of a branch of study which had previously been known as teleology, the study of the adaptation of organic
