Karl Friedrich von Gaertner was a German botanist and physician. He is known through his achievements in botany.
Background
Karl von Gaertner was born on May 1, 1772, in Göppingen, Germany. He was the son of 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.
Education
Karl 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 he earned a medical degree at Tübingen.
After earning his medical degree at Tübingen, Karl 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.
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. 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.
Gaertner was a member of the German Academy of Sciences Leopoldina and of the Royal Netherlands Academy of Sciences.
Personality
Physical Characteristics:
Like his father, Gaertner contracted an eye ailment in the course of his microscopical investigations. He therefore discontinued them and ceased his medical practice in about 1824.
Connections
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).