Geer, Charles De

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Geer, Charles De

(b. Finspång, Sweden, 10 February 1720; d. Leufsta, Sweden, 8 March 1778)


De Geer grew up in Holland and returned to Sweden in 1739, where, at the age of nineteen, he was invited to become a member of the Swedish Academy of Sciences. He had not yet published any scientific work but, since he was one of the country’s wealthiest men, the academy expected him to make generous donations after his election. Nothing came of that hope, but De Geer became one of the academy’s most outstanding and widely known scientists. He resided in Leufsta castle, which still belongs to the De Geer family and contains his large and extremely valuable library. His position brought him into close contact with the royal court, and he was made master of the royal household.

After Linnaeus, De Geer was Sweden’s most important and internationally known biologist in the eighteenth century. In contrast with Linnaeus, he was not primarily interested in descriptive systematics; he considered the study of “dead insects” both meaningless and useless. That did not prevent him from describing and naming several species, but such activity was a necessity; he had to name the previously unobserved species which he studied and whose biology he described. Otherwise, as he acknowledged, the biological description would be of little value. It is, however, of interest that in his seven-volume Mémoires he did not employ the binary Linnaean nomenclature until the third volume (173).

Although De Geer lacked a particular interest in classification and cataloging, his enthusiasm for studying the life and metamorphosis of insects was great. His position gave him plenty of time for all kinds of nature studies, the only work which could not be left to his large staff of servants. In the field De Geer made his brilliant observations; he placed insect larvae in cages and studied their metamorphosis; and with the microscope—the best and most expensive English make—he made morphological observations and drawings of insects and their structures. He was an exceptional draftsman, which is reflected in his illustrations.

De Geer’s scientific models were Leeuwenhoek, Swammerdam, and Réaumur. From the first two he drew the technique of using the microscope, and from the latter the method of biological observation. It is no coincidence that his monumental Mémoires pour servir à l’histoire des insectes (1752–1778) carries exactly the same title as Réaumur’s equally large work (1734–1742). When the first volume was published in 1752, De Geer was accused, doubtless on the basis of the title of the work, of compilation and lack of independence; it was only a rehash of Réaumur. The great injustice of these accusations strongly disturbed De Geer; he announced that he would not continue the work and had the remaining part of the edition of the first volume destroyed. Not until nineteen years later, in 1771, was it possible to persuade him to resume communication of his experience by publishing the other volumes. From then on, the volumes appeared in unbroken sequence and received the notice and appreciation they deserved. The seventh and last volume appeared posthumously, in the fall of 1778. As already mentioned, De Geer did not use Linnaeus’ binary nomenclature consistently; but a commentary introducing that principle of naming was published by Retzius in 1783 on the basis of De Geer’s work. The work was translated into German by the entomologist J. A. E. Goeze, who published it, together with an extensive and valuable commentary, in 1776–1783.

De Geer published about twenty entomological works, the majority in the Handlingar of the Royal Academy of Sciences. His first article, published in 1740, was a short and very valuable treatise on Collembola. His smaller articles were always of high quality; the majority were published in more or less revised form in the Mèmoires. He also published excellent studies on protozoa, which testified to the author’s abilities as well as to the quality of his microscope.

De Geer was in close contact with the greatest entomological authorities of his time, as the library at Leufsta shows. After his death his microscope and collections were turned over to the academy; the insect collections are now in the entomological department of the Swedish Museum of Natural History in Stockholm.

De Geer’s importance for biological research and for the technique of observing nature is much greater than the quite limited literature about him would indicate. Torbern Bergman, himself one of the great Swedish scientists of the eighteenth century, gave fine testimony about De Geer’s merits in the obituary that he read before the Academy of Sciences in 1778.


I. Original Works. De Geer’s writings include “Rön och Observation öfver små Insecter som kunna häppa i högden,” in Kungliga Svenska uetenskapsakademiens handlingar (1740), pp. 265–281; “Beskrifning på en märkwärdig Fluga kallad Ichneumon ater, antennis ramosis,” ibid. pp. 458–463; “Beskrifning på en Insect af ett nytt släagte kallad Physapus,” ibid (1744). pp. 1–9; “Om maskar funne på snön om vintern,” ibid (1749), pp. 76–78; and Mémoires pour Servir à l’histoire des insectes 7 vols. (Stockholm, 1752–1778), translated into German by J. A. E. Goeze as Des Herrn Baron Karl de Geer Abhandlungen zur Geschichte der Insecten, 7 vols. (Leipzig-Nuremberg, 1776–1783).

II. Secondary Literature. See Torbern Bergman, Aminnelse-Tal öfer Höf-Märschalken, Högväborne Friherren Herr Carl De Geer, hället 19 Decemb. 1778 (Stockholm, 1779); F. Bryk, in S. Lindroth, ed., Swedish Men of Science 1650–1950 (Stockholm, 1952), pp. 113–121; and A. J. Retzius, Caroli De Geer genera et specis insectorum equand, pertem reddidit, et terminologiam insectorum Linneanam addidit (Leiozig, 1783).

Bengt-Olof Landin