The Encyclopedia Americana (1920)/Biology
BIOLOGY. The study or science of living organisms, and the phenomena of life. Its field is the whole breadth of the organic world, and it seeks to mark the boundaries which separate living from inorganic nature,— to discover the principles that unify it, the processes by which living things have developed, the nature of life itself and the future in store for it. Biology, then, is the sum of all the special departments of study which deal with plants, animals and man in his animal relations, such as botany, zoology, anthropology, and their subordinate or associated sciences; that is, bacteriology, microscopy, physiology and many more. In his outreaching toward the causes and principles underlying its phenomena, the philosophical biologist must therefore understand organic chemistry, and the laws of electricity, light, heat, and mechanics, as they relate to animal needs; and at the other extreme he must consider psychology as an integral part of his domain.
This array of responsibilities and of objects for investigation seems too formidable for any one mind to undertake or a lifetime to encompass, and it would be were not the realm of living nature capable of resolution into simple elements; unified in its fundamental structure; and controlled in its developmental growth by definite “laws of being,” which have come more and more clearly into view as knowledge of details has increased. The classification and co-ordination of the enormous mass of facts incessantly poured into his laboratory and library by experimenters and observers, to illuminate the truth by some generalization, or to exhibit a plan, law, type of structure or growth, is the high purpose of the thoughtful biologist; and the greatest names in the science, — Aristotle, Leibnitz. Harvey, Malpighi, Linné, Buffon, Lamarck, Treviranus (who in 1802 first used the term biology), Cuvier, Galvani, Goethe, Lyell, Von Baer, Owen, De Blainville, Leuckart, Agassiz, Darwin, Wallace, Kowalensky, Müller, Haeekel, Marsh, Cope, Hyatt, Weismann and many others,— have been those of men who had these large aims in view, and have contributed toward a solution of the great problem of life. The living world may be pictured as an enormous bundle of tangled and interlaced cords of phenomena, which, moreover, are never quite stationary and fixed, but are always slowly, invisibly, altering and forming new entanglements. Every naturalist is at work upon some part of this bundle, endeavoring to extricate his particular part. In more cases he pays so little attention to anything else, and is so fascinated with the beauty of his single strand, that he draws but little out. In other cases men of larger view or more serious purpose, or societies of them co-operating, disentangle more. The great biologist is he who can perceive those who have found a clue, and is able to teach them and the others how still more surely to unravel the intricate threads of phenomena that entwine and conceal the great fact of life at the centre of the puzzle.
To drop the figure, the science of biology in its more restricted and ordinary meaning is the co-ordination of the observed facts and manifestations of the organic world into laws, and the discovery of the principle from which all proceed; that is, its object is to find an answer to the ever-present question of existence— What it Life? To this end goes on the incessant collection of facts in natural history, and it goes on joyously because any moment the biologist may come upon some fact or suggestion which shall contribute to the grand result.
Progress has been made. The study at first was nothing but a miscellaneous gathering of specimens and records of observations. Then a crude sorting out began. Men at first failed to distinguish between what was animate and what was inert. The winds, the lightning, volcanoes, springs were things of life. Later the broad distinction of organic from inorganic was perceived, but even now it is not known whether some of the manifestations of movement and response in certain “slimes” are purely chemical, or due to the presence of actual life.
The next step was the separation of the two great branches of the organic world — plants and animals. The broad features of these groups must have been apparent to primitive man, but it is only within comparatively recent years that such groups as the sponges, the branching forms of the corals, the spreading growths of the polyzoans, have been definitely placed among the animals. The names, “sea-anemone,” “moss-animal,” “zoophyte,” and the like, show the popular error or doubt as to these forms. The relationship of the minute or even microscopic hydroids and protozoans were still longer in doubt; and to this day there is a borderland in this great group (the Protozoa) of minute, unicellular objects where no one is able to draw a certain line between what should be called a plant and what an animal, or even whether some of the objects are organic at all.
As men perceived certain likenesses and unlikenesses the sorting of plants and animals went on crudely at first, on purely superficial or even fanciful grounds. This sufficed fairly well for some large and well-marked groups, as beasts, birds, fishes, insects, hardwood trees and the like, yet led to many mistakes, such as placing whales with the fish and the bats with birds. Meanwhile students here and there had become interested in special groups, and each called his pursuit a science. Thus arose Ornithology — the study of birds; Conchology, the study of shells (in which for a long time little attention was paid to the animal that made them!); Anatomy and Physiology, the study of structure, at first confined wholly to the human form, and only lately to animals in general, when it was distinguished as Comparative Anatomy; Botany, the study of plants; and so on. In each, men gathered and recorded specimens and facts, as a rule from a single neighborhood. Nevertheless, curiosity began to inquire beneath the surface. Plants were pulled apart, animals dissected and resemblances and contrasts of structure were noted. Naturalists traveled, and found that the creatures of the world were more numerous than had been suspected. and varied with climate, soil, height above the sea and diverse conditions, and when records and specimens from many localities were gradually accumulated in great museums, likenesses and contrasts appeared that had not been visible in the small local cabinet. Materials were thus obtained for more intelligent arrangement, and classification became one of the most important sciences in the scope of biology. The great service an accurate arrangement of living things would render to an inquirer as to their nature was perceived, and scientific men everywhere searched for facts which should fill the gaps in their knowledge. The criteria were made more and more exact, and as classification was perfected it became increasingly evident that the criteria for all branches were substantially similar, and there came to be perceived certain plans of structure. One of the latest and most powerful aids to investigation, the result of the perfecting of the microscope, was the science of Embryology, or the study of the development of a plant from the seed or of an animal from the egg. It went hand in hand with Histology, (he study of tissues, and both disclosed the new truth that the structure of both animals and plants was at its basis the same — a cell filled with “life substance” (protoplasm); and that the multiplication of these cells constituted the growth, and their arrangement and limit the form and bulk, of every animal and plant. It was furthermore ascertained that an egg or a seed (in which it is believed that every animal plant begins, in spite of some apparent exceptions) was simply a cell differing, so far as we can yet see, from other cells in the body only by its possession of the potentiality of independent life under the fostering of suitable conditions. Classification had already shown that its groups might be arranged in something like a series from those very simply organized (the one-celled protozoa at the foot of the list) up to the highly complex. Now embryology showed that the changes each individual passed through from egg to birth were a series of changes from simplicity to complexity and furthermore that they suggested a parallel to the features of the successive groups in classification, especially to those of the subordinate ranks of the subject's own class. Palæontology enforced this by a similar parallel, finding that the most ancient animals fossil in the rocks were of simple and generalized structure as compared with those of more modern geological formations: in other words, that structural development has also been historic development.
All these facts changed the point of view of the biologist. Instead of looking at separate animals and seeking to find differences upon which to make new species and subdivide groups, he is now seeking for likenesses — points of unity. It was long ago suggested to thoughtful minds that the world was not always as we found it, but that for a vast period there had been a slow, persistent growth and unfolding. The phenomena of the inorganic world pointed the same way, and hence arose the "nebular hypothesis" — the explanatory theory that the universe developed from a gaseous state, and the earth, as one of its parts, was slowly perfected in pursuance of the forces inherent in its origin. Biologists are only carrying this theory out in a detail when they argue that the facts in their hands can he accounted for only by the supposition that the living beings on the earth have been slowly developed from a primitive source, comparable to the germ-cell, along unequal and ramifying lines of progress under the influences of their changeable environment. This is only a detail, — a flower, — of the general unfolding of the universe which is well called its evolution; it is an organic evolution.
In the light of this grand generalization biology is now progressing with an organized force for investigation of the great question as to the origin and nature of life. This has not been answered by any of the fruitful hypotheses, like those of Darwin or Lamarck, which, have placed such effective tools in the biologist's hands. Toward the solution of this problem all scientific men are working, consciously or unconsciously. In aid of this purpose are pushed forward the incessant and world-wide collection and preservation of preserved animals and plants — museum specimens; and the systematic and accurate observation and record of local species and their habits and instincts. Much of this seems trivial and dry as dust in the eyes of the ignorant or of those whose minds, being occupied with other thoughts, forget the reason and tendency for these ever-multiplied details of natural history. Patient students toil to the same end in laboratories of anatomy and microscopy, laboriously gather statistics of variation, compile lists of geographical distribution, chisel out of the rocks remains of extinct races, and sort and re-sort in experimental classifications — all this in order to provide the generalizers of the science with more and better factors for the solution of the great focal problem. What is Life, and how came it to be? What has been the net result so far? In one direction the conviction of the universal eminence and force of the principle of evolution; in another the realization of the independent life and action of each separate cell. To the study of the constitution, qualities and behavior of the cell, whether standing alone in the unfertilized egg, or as a naked monad, or one in an interdependent association of millions building up a complex organism, has biology come at last; and not until it has vanquished the difficulties presented by this atom of living and potential protoplasm, the cell, will it accomplish its full purpose.