ALEXANDER VON HUMBOLDT. THE POPULAR SCIENCE MONTHLY. DECEMBER, 1883. By ÉMIL DU BOIS-REYMOND, RECTOR OF THE UNIVERSITY OF BERLIN. PROPERLY to appreciate Alexander von Humboldt's life-work, one must form a conception of the intellectual atmosphere from which he issued. The opinion may not unfrequently be found among laymen that there was no real German naturalist before Humboldt. They are accustomed, as if to a Hercules, to ascribe all deeds to him. It is not necessary to say that this is all a mistake; but even professional naturalists frequently remember too little of our older history. I do not speak of the almost ancient figures of Copernicus, Kepler, and Otto von Guericke; nor of Leibnitz, who had as clear a comprehension of the fundamental ideas of nature as we; but the eighteenth century displays names worthy of the highest degree of respect, almost as brilliant as these. The Bernoullis developed analytic mechanics, Euler recognized the feasibility of achromatic glasses, Tobias Mayer reformed the theory of the moon, Lambert laid the foundation of photometry, Kant conceived the nebular hypothesis, and William Herschel, whom we count among our own, enlarged our knowledge of the starry heavens almost as if the telescope had just been discovered. Had the Dutch physicists left him time, the Canon of Camin would have certainly possessed a perfect title to have the Leyden-jar called by his name. Volta's electrophore is really Wilcke's discovery. Segner's water-wheel, Leidenfrost's and Sulzer's experiments, became the germs of important discoveries and applications. Stahl's phlogiston, even if it was a false conception, and Haller's elementa, in the long run, made chemistry and physiology German sciences. Herr Hofman has very lately taught us how to appreciate Marggraf's services in technical chemistry. Vater and Lieberkühn are still mentioned in the finer anatomy, and the first part of Sömmering's classical activity belongs to the same category. Caspar Frederick Wolf reformed the development-history and outlined the doctrine of the metamorphosis of plants. As early as 1785 Blumenbach, the founder of physical anthropology, led a class in comparative anatomy. In natural history, Rösel earnestly advanced the labors of Swammerdam and Réaumur; Ledermüller described the creatures which he called infusoriæ. Gleditsch performed the experimental demonstration of the sexuality of the phanerogams by fertilizing the palms in our botanical gardens with pollen from Leipsic. Even in classification, in which the rivalry of the seafaring nations with the Germans was so arduous, a few, like the creator of our fish-collection, Bloch, won imperishable fame. Germans also approved themselves as scientific travelers: the two Forsters, Cook's companions around the world; and in connection with the Russian expedition for observing the second transit of Venus, our Pallas, as a student of the Siberian fauna. Finally, in geognosy had Werner secured the uncontested leadership for the Germans as the pre-eminently mining people, among whom Agricola had previously created mineralogy. This enumeration, which might be considerably extended, shows what good progress German natural science had made in the last century. Indeed, it is doubtful whether any other people can boast of a greater richness of notable achievements during the same period. But, toward the end of the century, the aspect was changed, to our disadvantage, and not without our fault. After its early bloom in the middle ages, and the activity of the Reformation, the German mind, disturbed in its development by the Thirty Years' War, remained, as respects literary production, in the background. At most, it trifled a little in a tasteless way.