# Popular Science Monthly/Volume 52/February 1898/Scientific Progress in the Closing Century

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* SCIENTIFIC PROGRESS IN THE CLOSING CENTURY.
By Prof. LUDWIG BÜCHNER.
CENTURY of enlightenment—century of science—century of reconciliation—as such respectively may be characterized the eighteenth, the nineteenth, and the twentieth centuries; though in so characterizing the last we have somewhat forestalled time. But the designation of the present century as that of science can hardly be disputed; for progress in human knowledge and in consequent power has been so great and far-reaching in this century, and so rapid within the last few years, that in this respect no preceding century can at all compare with this.
Astronomy.—It is known that Copernicus, fearing clerical persecution, was compelled to hold back his great work on the revolutions of the heavenly bodies for thirty years, and that when finally published it was condemned and prohibited as heretical. The telescope also was put under the ban, because, according to the view of the Church, it permitted men to see farther than God by the of the human eye intended them to see. Nevertheless, it was the telescope that put a definite end to the narrow notions arising from the geocentric error, and ousted the earth and its inhabitants from their imagined high place as center of the universe. But the crowning of the astronomical edifice founded on these discoveries occurred only in the century at whose exit we are standing, and this through the founding of the important science of astrophysics and the knowledge acquired thereby of the chemical and physical constitution of the heavenly bodies by which we are surrounded. These researches were initiated by the wonderful discovery made in 1859 by Kirchhoff and Bunsen of the spectral analysis or the language of light, which has furnished special elucidation of the chemico-physical constitution of the sun, which elucidation must have appeared impossible to previous science. Spectrum ​analysis, also, in conjunction with the study of the curious double stars (which have been more exactly recognized within the last decade and are now known by the thousand) has brought about the highly important conviction of the unity of what is to us the visible universe, and the correspondence of its elements and forces and of the laws by which the whole is governed. In the same science, the progressive improvement of the astronomical perspectives and giant telescopes has furthermore made possible a much more extended insight into the infinite depths of the universe, and, supported by the art of photography, has made known the existence of new stars—among them fixed stars or suns—a hundred or a thousand times as great as our sun. Even more important is the discovery in the same manner of those strangely rotating primeval nebulæ, composed of incandescent gases, which are nothing else than stellar systems in a state of formation. Observation of these has raised to almost a certainty the theory of Kant and Laplace as to the origin of those systems. One of the strangest of those systems is the great nebula in Andromeda which can be seen with the naked eye. The photographic image of this object, obtained by the English astronomer Dr. Roberts, by means of a twenty-inch reflecting telescope, exhibits distinctly the various phases of its development. The improved telescopes of the present time have furthermore provided us with such an intimate knowledge of the constitution of the surface of our moon that it is now better known than some parts of the surface of the earth—as in the interior of the great continents of Africa, Australia, and America. Similar information, though to be taken with reserve, was obtained from the remarkable phenomena observed on the surface of the planet Mars. The interpretation of these features has not been thus far absolutely settled, but in the opinion of eminent astronomers they indicate the presence on that planet of thinking beings. To the present century also belongs the somewhat older discovery of the planet Neptune, which was made in such a wonderful way by Leverrier and Galle in 1846. This discovery must be regarded as one of the greatest triumphs of astronomical science, since it was the fruit of a demonstration by mathematical calculations of the existence of a heavenly body, while the actual finding and identification of it were achieved afterward by means of the telescope. In like manner, by the application of the laws of gravitation to the peculiar movements of the magnificent fixed star Sirius (the Dog Star of the ancients), its character as a double star was recognized twenty years before Clark, in Boston, discovered, on January 31, 1862, its companion, and by this discovery furnished the weightiest argument in support of the universality of the law of mass attraction.
​Physics.—With astronomical science ranks, as a matter of course, physical science and the great discovery of the conservation or persistence of force, which now like an animating breath pervades all natural sciences, and deserves to be classed with the greatest discoveries of all time. Guessed and clearly predicted by Friedrich Mohr as early as 1837, this principle received its scientific confirmation from the German Robert Mayer (1842) and the Englishman Joule (1842-'49). Both these scientists had worked independently of each other. The validity of this great theory was first established by proving the identity of heat and motion (because proof as to these was easiest), and, the mechanical equivalent of heat having been calculated, was very soon fixed for all the forces of Nature. Thus the unity and immortality of force were demonstrated.
The physics of our century shows another great advance in what is called the kinetic theory of gases, for which Clausius and Maxwell paved the way, and which permits us a deep insight into the infinite fineness of matter and the inconceivable velocity of its internal motion. According to Clerk Maxwell, the most minute living being that can be seen under the most powerful microscope still contains a million (according to Tait, two million) organic molecules or atomic groups; so that we can not form any conception whatever of the incalculably great number of the finest histological elements for which perhaps no method of investigation is at our command. Finally, the century, shortly before its departure, has accomplished in the physical domain one of its most valuable feats by the discovery of the X or Röntgen rays, which permit our eye to penetrate to the innermost depths of objects hitherto regarded as opaque, and thereby make almost true the marvels of the Arabian Nights. Not less wonderful and unexpected is the success, likewise belonging to very recent time, attained by the experiments in liquefying and solidifying gases, like oxygen, nitrogen, carbonic acid, chlorine gas, and atmospheric air.
Chemistry.—As regards the domain of chemistry, this science, not to mention the numerous smaller discoveries important to industry and therapeutics, has achieved one of its greatest triumphs by its surprising penetration into the organic domain, and the consequent elucidation of the relation of the vegetable and animal metabolism. These discoveries, chiefly initiated by the renowned Liebig, in the years 1848-'55, were productive of the most beneficial results in the development of the physiological and medical sciences, as well as in agriculture. As a consequence of this knowledge, we have to greet the successful experiments in the artificial production of organic matter or the chemical synthesis inaugurated by the French chemist Berthelot in 1856. At present a whole series of genuine ​organic substances, such as alcohol, various kinds of ether, grape sugar, organic acids, fats, alkaloids, vegetable oils or perfumes, etc., are being manufactured in a purely chemical way, and the hope is well founded that in course of time we may also succeed in preparing directly from the elements sugars and albumins—yea, even the protoplasm or that organic primal substance out of which all living beings are evolving. What chemistry even now is capable of achieving is shown by the preparations made from coal tar of practicable pigments, perfumes, saccharines, and drugs.
Finally, we must mention in this place the discovery of argon, a hitherto unknown element of the atmospheric air, as well as the successful preparation of acetylene by Professor Moisson. This is a luminous gas which is sixteen times stronger than common gas, and has five times the illuminating power of Auer's gaslight.
Geology.—As we owe to the progress in chemistry the refutation of the theory of a vital principle, geology in like manner has disproved, chiefly through the labors of the gifted English geologist Lyell (1830-'33), the formerly accepted theory of great physical catastrophes or terrestrial revolutions and of separate acts of creation, and has shown that the past of the history of our globe (which in its evolutionary process advances slowly but continuously) is nothing but its unrolled present.
Paleontology.—In close connection with geology is paleontology, or the knowledge of the former life of our globe. This has been raised to the rank of a science only during the present century. Now this science has so far advanced that we can survey the gradual development of the entire organic world, and find that those transitional and intermediate forms required of the evolutionary theory are no longer missing. The vast North American plains are especially remarkable as having been found to be rich treasure houses of such forms.
Anatomy.—Closely connected with paleontology are anatomy and the discovery made in this science of the cell as the primordial element or fundamental form of the whole organic world. This discovery was made by Schwann and Schleiden in 1839, after the microscope had been brought, through the efforts of Amici, to such a perfection as to make possible by its use the more and more subtle investigation of animal tissue. Through the discovery of the cell, the unity, as to kind and origin, of everything living was demonstrated; and it was shown that even the highest and most complicated organisms were simply combinations of cells in a more or less changed condition. Then, in 1859, Virchow made an ingenious application of the cell theory to medical science. Virchow, in his Cellular-Pathologie, searched in the modified cell for the nature ​of disease, and promulgated that doctrine, so bold for his time, "Omnis cellula ab cellula" (every cell from a cell)—a doctrine that will always stand like a corner stone of the temple of science. The continuity of everything living expressed by this doctrine was confirmed later on by the progress made in comparative anatomy, so that the fundamental plan common to the type of vertebrates could be traced to its last details, and it was shown that between animal and human structure the characteristic of distinction is not absolute, but only relative. Of special importance in this connection is the proof that even the organ of mind—i. e., the brain—is no exception to the general rule, and that it is built on a common fundamental plan in both man and animal.
After all, not much had been gained for a philosophical view of Nature and a natural explanation of generation, in its inception, by the discovery of the cell as the primordial form of the organic world, the cell itself being too high and complicated a formation to be regarded as rudimentary. There was therefore a hiatus in our knowledge which gave the opponents of the theory that the world is the result of a series of changes governed by natural laws a convenient ground for declaring the theory untenable and false. But this difficulty also was removed by the discovery (likewise belonging to our century) of protoplasm, or the original primordial substance, made by Max Schulze in 1863. This protoplasm, consisting of shapeless organic matter, is identical with Haeckel's celebrated monera, or those formless albumin lumps, those organless organisms out of which the true cell only develops after a long series of intermediate stages. And the moner itself, in all probability, is not the first step, but the ultimate product of previous stages of development in the process of the transformation of the inorganic into the organic. Naegeli's mechanico-physiological theory of descent goes even so far as to declare the distance between the moner and the true primordial plasma substance far greater that that between the moner and the mammal! In the light of these discoveries and the consequent conclusions, the much-ventilated question of primal generation, which formerly was covered by impenetrable darkness, no longer presents any difficulty in the way of scientific explanation.
Physiology.—In close connection with anatomy and the history of evolution, which are occupied with the physical building up of the organisms, stands physiology, or the science of the functions of the organs. Here we notice, in the first place, the great discovery made by von Baer, in 1827, of the ovum of the mammals and of man, in its original place in the ovary. This discovery was soon after followed, in 1844, by the elucidation by Th. Bischoff of the ​process of fecundation and generation, which theretofore had been wrapped in the deepest obscurity. Four years later, in 1848, followed Du Bois-Reymond's researches in animal electricity and the roof that the nerve is not, as formerly believed, a mere conductor, but a self-generator of the electricity originated by chemical metabolism and the transformation of what is designated as potential force or elasticity into living force or motion by virtue of the great principle of the conservation of force.
Under the head of physiology, special mention must also be made of the great successes that accompanied the researches of Messrs. Schiff, Ferrier, Munk, Nothnagel, Hitzig, Fritsch, Broca, Flechsig, and others concerning the localization of the various activities of the soul, or the divisions of labor taking place in the brain, and the topographical distribution of certain functions of the brain on its surface—researches which have not by any means reached their end. The most important among these is the discovery, made first by Broca, in 1861, of the controlling center of speech at a definite place in the fore part of the brain. Morbid degeneration or destruction of this spot is the cause of aphasia, or speechlessness. This discovery also satisfactorily explains why the large manlike apes which are almost devoid of that part of the brain can not speak, notwithstanding the formation of their larynges is similar to that of man. Not less important are the entirely new researches of Professor Flechsig on the so-called centers of association in the brain and the definite proof furnished by him that all thinking springs from the senses, inasmuch as it is only by the gradual development of those centers that the action of the different organs is connected, and thus thinking and intelligence are made possible.
Zoölogy.—Besides the numerous acquisitions of systematic zoölogy, special mention should be made here of the researches as to the life in the sea. These have been prosecuted largely through the zoological marine stations supported by Government, and have been rendered more effective by means of improved apparatus which made possible the acquisition of knowledge as to the deep-sea fauna. The results enabled Haeckel to establish his renowned Gastræa theory, according to which all animal species—however far differentiated—owe their primal origin to a single primitive form of the greatest simplicity that might be properly designated as "primitive stomach." To the zoölogical researches of the century we are also indebted for the better knowledge of those strange animal creatures nearest to man whose existence was still doubted or relegated to the realm of fable as late as the last century even by scholars, although as early as 500 b. c. the Carthaginian Hanno had seen gorillas on the western coast of Africa, and described them as wild "haired men." ​Now, the so-called anthropoids or large manlike apes may be seen either dead or alive in many museums and zoölogical gardens.
Biology.—Closely connected with zoölogy is biology, or the science of life, which undoubtedly has achieved the greatest progress made by physical science in the century by the promulgation and victory of the theory of descent by evolution, a theory brought forward by Darwin in 1860, and developed by Haeckel and others. Nearly related to it are the above-mentioned remarkable discoveries in the domain of paleontology and the knowledge of numerous intermediate forms which formerly had been disregarded as unimportant "varieties."
Archæology.—The existence of the fossil man, which had been doubted so long, has been proved, and the geological age of the human race established. The series of discoveries coming under this head was opened in the years 1830-'40 by the discovery, made by the French scientist Boucher de Perthes, of man-made diluvial flint axes in the Somme Valley in the north of France. Since then the researches concerning the age and the preliminary history of mankind have become the favorite study of the time and of scholars, and there has come into being within a comparatively short time a literature on this subject the wealth of which can hrdly be surveyed. The discoveries in this vast and interesting domain are accumulating from year to year to such an extent as to give rise to a new and successful science of archæology. While on the one hand this science teaches us that the existence of man on earth must be shifted back into hoary ages to which the historical period can not be compared at all, it shows us, on the other hand, that this period considered geologically—i. e., when compared with the periods of evolution of the earth—is of itself a very recent and new one. It is for this reason that the origin of man must be regarded as the crowning or culminating point of the whole organic evolution—a point beyond which the development of the world was no longer carried on by Nature, but by man. A highly desirable completion of these studies on the primal history of the human race was supplied by the great progress in ethnology made possible by the enormous traveling facilities of our century.
Psychology.—Closely related to anthropology is psychology, as to which the conviction prevails in authoritative circles that it should not be classed with the philosophical sciences, but with the physical; or at least that it must be treated after the physical method if any tangible result is to be attained. It was this mode of treatment that achieved the afore-mentioned result of the measurement of the duration of human thought. We owe also to this method the better knowledge of the animal soul and the foundation for ​comparative psychology, analogous to comparative anatomy, which latter has been in an advanced stage for a long time. Finally, in the psychological domain we owe to modern times the knowledge of the strange phenomena of double consciousness and of hypnotism with the phenomena of suggestion, the study of which is calculated to throw on the mental being more light than could the most voluminous works on psychology of former times, which were the result of self-observation and self-deification. Unfortunately, these phenomena have given food to the inextirpable belief in miracles, and furnished new support for unfounded spiritualistic and spiritistic chimeras of every kind, such as thought-reading, telepathy, magnetic rapport, the belief in ghosts, spooks, etc.
Medicine.—If we finally mention medicine or therapeutics as a branch of physical science we have here also to record a series of the most important advances in the course of the century. At the head stands the method of auscultation or of listening by means of an ear trumpet to the sounds in the chest in order to discover disease in the lungs and the heart. This method was invented by the French physician Laennec in 1819, soon after the method of percussion had been improved by Piorry, while the foundation of pathological anatomy through Professor Rokitansky, and of pathological histology by Professor Virchow, which soon after followed, advanced medicine to a real science. Another invention, highly important in practice—subcutaneous injection—was made by A. Wood in 1850. More recent than all this is the very important discovery of the infectious micro-organisms or bacteria as the causes of disease. This discovery, which led to the application of disinfection, in common with the introduction of chloroform and cocaine as anæsthetics, on the one hand, cleared the way for the acknowledged wonderful progress made in surgery, and, on the other hand, materially facilitated the combating of diseases caused by those organisms by prophylactic measures.
We must also allude to the invention of a great number of new remedies obtained by means of chemistry, as well as of new methods of curing ailments (e. g., massage). We must mention, too, the general introduction of vaccination, which has proved one of the greatest blessings to mankind. Whether the injection of fluids as an immunity against certain diseases (e. g., diphtheria), tried according to the same method, will fulfill the hope entertained is a question the solution of which must be awaited after the unfortunate failure of a similar procedure employed in tuberculosis. It seems, however, as though this so-called "serum therapeutics" in its further development might accomplish great results in the field of infectious diseases. The ascertaining and location of internal diseases ( ​particularly as to the skeleton) has likewise been advanced, as previously referred to, in marvelous manner by the application of the "X" or Röntgen rays to the illumination of the human body.
To the great progress in human knowledge must be added the no less gigantic advances in power accomplished by the nineteenth century, and effected by the greater knowledge and mastery of the forces of Nature. Above all must be noticed here the forces acquired by the control of steam, conquering all resistance and giving birth to those noble children of the century—railroads and steamboats. This has brought the powers of legendary giants under the commanding hand of man. A few decades have been sufficient to span the greater part of our globe with space and time annihilating messengers, and by means of the even more marvelous inventions of the telegraph and telephone to bring into direct communication with each other the most distant parts of the earth's surface. Another child of this our century is the phonograph, whose astonishing achievements remind us of fairy tales; and another is the art of photography, which, as already said, has with an unanticipated success been placed in the service of science (astronomy, telescopy, geography, and ethnography). Its instantaeous pictures have brought it about that the successive movements of a complete occurrence are separately reproduced before our wondering eyes as though we saw a repetition of the actual scene. This art, however, still awaits one of its greatest triumphs in the production of colored pictures. We must also mention the invention of dynamite, a product making practicable the exertion of unprecedented energy, and so indispensable wherever great mass effects are to be attained; and also of smokeless powder, which may prove beneficent in abating or even completely abolishing the great continental wars.
Finally, our century has witnessed the union of electric force with chemistry and technics in the form of electro-chemistry and electro-technics, which open the brightest vistas into the future. For the wonderful force of electricity excels in readiness of application and utility all other forces of Nature, and beyond any other vanquishes the checking barriers of space and time. It can, without any special means, be almost directly derived from or changed into all other forms of natural force, and proceeds with an extraordinary velocity through the prescribed paths of the conducting wires. It can, therefore, at any moment be conducted to any place where its effect is required. Dwellings are now illuminated by electricity almost everywhere, and if heating by the same agent and the cooking of food by means of it become common, then is foreshadowed an almost paradisiacal state, in place of the conditions of existence now ​prevailing with their attendant trouble, uncleanliness, dust, vexation, and disease. And should electro-technics succeed—as there is well-founded hope that it will—in solving the problem of obtaining electricity direct from the fuel, instead of by an expensive indirect method as heretofore, the far-reaching effect of such success can scarcely be overestimated. As with respect to material progress this century is fittingly called the Century of Steam, so most likely the coming century will have to be designated the Century of Electricity, when the more extended control of the forces of Nature by the human mind shall have taken an immense stride in the forward direction. If we add to all this that the grand material as well as intellectual development of the great land of liberty in the far West of our globe, the like of which has never been seen before, promises to continue in the same or even a higher degree, then the men of the coming century will of necessity be more profoundly impressed than the children of the present by the achievements of human intellect and human power.
It may be that we are, with respect to the coming century, in the same immature mental condition in which the people of the eighteenth century were with regard to the nineteenth. If some one in the preceding century had dared to predict the wonderful achievements of the nineteenth, he would probably have been declared a fool, and treated as was Robert Mayer, in Germany, in this century, who, after the discovery of the law of the conservation of force, was put into an insane asylum. A like fate might befall the man who should dare now to cast a horoscope for the twentieth century, and to predict the progress of the human mind in the various domains of scientific research. After all, those may be right who, in spite of all those acquisitions on which we so justly pride ourselves, are of opinion that we are still moving in only the initial steps, in the leading strings of evolution, and that we are yet very far from the goal of those material and ideal aims which the human race in its unremitting onward struggle is destined to attain, or to show its capacity of attaining. The great Sir Isaac Newton used, perhaps, the most appropriate simile when he compared men with children who on the seashore are picking up here and there a curious pebble or colored shell while the great sea of truth lies still unexplored before them. We can only conjecture as to the probable progress, as we can not know which position we occupy in the course of human evolution, whether we are still in its beginnings or well advanced. This lies hidden in the bosom of the future. We therefore discontinue this line of thought, and remark here again that unfortunately this great progress in knowledge and power in our century has not extended to the moral, general intellectual, literary, ​or social domains, and perhaps we should except also the realm of politics. To grasp and to establish the hitherto wanting but yet so necessary harmony between being and thinking will probably be the chief task of the century soon to come in.
As regards the sciences thus far not mentioned (philosophy, theology, jurisprudence), there is, to our knowledge, much movement to be noticed, but comparatively little real progress. An exception must be made as to history, which as Kulturgeschichte (history of civilization) has assumed a scientific character contrasting markedly with its previous form. The same is true of the history of religion, which has given a well-deserved attention to the ancient Hindu religions, especially the venerable religion of Buddha; furthermore, the successful study of antiquity, which, especially in connection with a branch of physical science or geology as archaeology, has furnished the most valuable disclosures as to prehistoric times. Political economy, statistics, and hygiene also may look back on their achievements with pride. The ethics of moral science has also derived great profit from the revelations of physical sciences on the gradual acquisition and transmission through heredity of mental and moral qualities. The like can be said with even more emphasis of general philology, which happily applied the principles of the theory of evolution to the great problem of the origin of languages, and proved that the laws according to which species and languages originate, grow, and, through the extinction of intermediate links, separate from each other, are identical.
Furthermore, in all domains of human knowledge, without exception, a great number of important and valuable detail researches have been made which, in their totality, also tend to raise their respective sciences to a higher level.