Gaertner, Karl Friedrich von

(b. Göppingen, Germany, 1 May 1772; d. Calw, Württemberg, Germany, 1 September 1850)

botany.

Gaertner was born out of wedlock to Joseph Gaertner and Maria Rebekka Mütschelin. His father, who never married, officially recognized him in 1773 and legally adopted him in 1787. Gaertner’s paternal ancestors were apothecaries and physicians; his father also acquired a reputation as a botanist. Appointed professor of anatomy at Tübingen in 1761, Joseph Gaertner became professor of botany and natural history at St. Petersburg in 1768; until 1770 he was also in charge of the botanical garden and the natural history museum there. In addition, he undertook several scientific expeditions to various regions of Europe. His masterpiece was De fructibus et seminibus plantarum (1788–1792). The studies in comparative plant anatomy presented in this work contributed to the development of carpology and of the natural system of classification.

Gaertner spent his youth in his father’s home. He attended the local Latin school and then, from October 1787, the lower convent school in Bebenhausen. In 1791, after a two-year apprenticeship at the royal pharmacy in Stuttgart, he began to study medicine at the Hohe Karlsschule. His interest in chemistry having been awakened by K. F. Kielmeyer, he went in 1794 to Johann Göttling’s laboratory in Jena, where he also heard Christoph Hufeland’s lectures. The following year he studied at Göttingen. In 1796, after earning his medical degree at Tübingen, he set up practice in Calw. He traveled to Paris, England, and Holland in 1802 and met the leading natural scientists of the period, many of whom had been friends of his father, including Georges Cuvier, A. L. de Jussieu, J.P.F. Deleuze, R. L. Desfontaines, Joseph Banks, and K. P. Thunberg.

In 1803 at Calw, Gaertner married Christine Sybille Wagner, the daughter of a wholesale merchant. His descendants include the political economist Gustav von Schmoller (a grandson) and the chemist Walter Hückel and the physicist Erich Hückel (greatgrandsons). Gaertner was granted a title of personal nobility in 1846.

Like his father, Gaertner contracted an eye ailment in the course of his microscopical investigations. He therefore discontinued them and ceased his medical practice as well. Beginning about 1824 he devoted his energies entirely to research on plant hybridization. Gaertner, who conducted his studies as an independent scholar, became a member of the Leopoldina in 1826 and of the Royal Netherlands Academy of Sciences in 1849.

Gaertner’s earliest research dealt with medical and physiological questions and with the chemical analysis of organic substances, including bone and urine. After 1800 he concentrated exclusively on botany. He prepared a supplementary fifth volume on the cryptogams to J. G. Gmelin’s Flora Sibirica as well as a further supplement to that volume containing data on the plants his father had gathered in the Ukraine. Following his trip abroad in 1802, Gaertner worked until 1805 on editing another supplementary volume to the Flora, this one dealing with carpology and written by his father. He then began a series of systematic and morphological investigations of the grasses.

The writings of his father’s friend J. G. Koelreuter had already drawn Gaertner’s attention to the problems of the hybrid fertilization of plants. When F. J. Schelver and his student A. W. Henschel again brought the sexuality of plants into doubt on the basis of principles derived from Naturphilosophie, the question became the subject of much debate. In 1825, Gaertner began comprehensive research on this problem after planning and beginning a general treatise on plant physiology. He published his first results in 1826, and he made further contributions almost yearly. In 1837 he won a prize for his solution of a problem presented by the Netherlands Society of Sciences at Haarlem. The first part of his masterpiece, Versuche und Beobachtungen über die Befruchtungsorgane der vollkommeneren Gewächse . . ., appeared in 1844; the second and larger part in 1849, under the title Versuche und Beobachtungen über die Bastarderzeugung im Pflanzenreich.

The first part of this work treated the relationships and conditions of natural and artificial fertilization, as well as the functions and alterations of the individual parts of the flower during fertilization. The second part reported results of experiments carried on over decades; the experimental methods themselves were described in a supplement. In this treatise Gaertner set forth the different ways in which hybrid fertilization can occur and discussed the capacity for hybridization among the various systematic units (family, genus, species, variety). He also considered the question of the “regularities” in the behavior of several generations of hybrids, although he did not formulate any general rules. He referred to certain dominant characteristics as “decidirte Typen” (“definite types”). He observed alterations of individual characteristics but did not study them systematically. He denied the possibility of “the transformation of one species into another through hybridization” and believed in the stability of species, which he regarded as fixed types. Gaertner classified hybrids “according to their structure and origin” and collected data on the general “characteristics and properties of hybrids,” as, for example, those pertaining to their fertility.

Although Gaertner’s general theoretical conclusions were deficient in terms of contemporary biological knowledge, his writings were extremely rich in observations, presented new methodology, and, in sum, constituted the first comprehensive treatment of the problem of hybridization. In them the sexuality of plants was definitively established, and at the same time the attention of researchers was drawn to the biological problems connected with sexual reproduction. Charles Darwin read Gaertner closely when he was developing his theory of pangenesis. However, Gaertner’s work achieved its greatest impact through its influence on Gregor Mendel, whose investigations were directly inspired by it.

BIBLIOGRAPHY

I. Original Works. Gaertner’s major works are “Fortgesetzte Nachrichten über Bastardgewächse,” in Flora (Regensburg), 10–21 (1827–1838); “Over de voortteling van bastaard-planten,” in Natuurkundige verhandlelingen van de Hollandsche maatschappij der wetenschappen te Haarlem, 24 (1844), 1–202; Versuche und Beobachtungen über die Befruchtungsorgane der vollkommeneren Gewächse und über die naturliche und künstliche Befruchtung durch den eigenen Pollen (Stuttgart, 1844); and Versuche und Beobachtungen über die Bastarderzeugung im Pflanzenreich (Stuttgart, 1849).

II. Secondary Literature. An obituary is in Flora, 34 (1851), 135–143. See also F. Reinöhl, in Schwäbische Lebensbilder, III (Stuttgart, 1942), 190–198, with portrait, bibliography of his works, and list of the literature.

Brigitte Hoppe