Caspar Friedrich Wolff

Kaspar Friedrich Wolff was one of the founders of embryology and established the doctrine of germ layers. He was born in Berlin, the son Johann Wolff, a tailor and his wife Anna Sofia Stiebeler. He began his medical studies at the Medical-Surgical College – Collegium medico-chirurgicum – in Berlin (1753-1754) and in 1755 enrolled at the University of Halle, where he graduated M.D. in 1759 and obtained his doctorate on November 28 that year with the famous dissertation Theoria generationis, In this work he presented his new theory of epigenesis that gave the death-blow to the entire theory of preformation. The dissertation, criticized by Albrecht von Haller (1708-1777) and Charles Bonnet (1720-1793), who found the theory false, ranks among the most important essays ever written in the whole range of biological literature.

In 1761, at the height of the Seven Years War (1756-1763), when Prussia was at war with Russia and several other countries, Wolff became a field doctor in the Prussian army. Through the Geheimrath Christian Andreas von Cothenius (1708-1789) he obtained a post at a field hospital in Breslau (now Wroclaw, Poland) and was able to begin his anatomical research as well as lecturing. As he was gradually relieved of his practical duties, with more opportunity to concentrate on lecturing, having Christian Ludwig Mursinna (1744-1823) as his Amanuensis.

When the seven years war ended in 1763 the field hospitals were closed and both Wolff and Mursinna lost their jobs. Wolff returned to Berlin, now concentrating his efforts on natural history. He was a controversial figure at the faculty, where his attempt in 1764, like a previous attempt in 1762, to obtain permission to lecture were opposed by the professors of the Medical-Surgical College, who had guild privileges to teach medicine. Religious opposition to his theories on generation probably also played a part in this, and perhaps jealousy.

However, he obtained the right to give private lectures, and from 1763 Wolff gave private lectures in anatomy, physiology, and medicine. The following year he restated his theory of generation and replied to Haller’s and Bonnet’s criticism in Theorie von der Generation – further decreasing his chances of obtaining a professorship.

But despite ardent efforts he was unable to obtain a chair. In 1760-1761 the Swiss mathematician Leonhard Euler (1707-1783), on behalf of the Prussian Academy of Science, had tried to obtain a post for Wolff at the St. Petersburger Academy of Sciences. This was unsuccessful, but in 1767, on Euler's initiative, Wolff was ofefred, and accepted, an invitation to St. Petersburg to enter a chair of anatomy and physiology at the St. Petersburg Academy of Sciences.

He travelled to Russia with his wife in May 1767 and later that year presented to the Academy De formatione intestinorum praecipue. During the next twenty-seven years he published thirty one memoirs in the Academy’s Proceedings, including several that were devoted to anatomical research on the muscles of the heart and on connective tissue. He paid special attention to the study of human monstrosities, which were collected in the Academy’s anatomical cabinet (which Wolff directed ) of the Kunstkammer. Surviving manuscripts indicate that Wolff prepared a major work on the “theory of monsters,” in which he attempted to systematize his epigenetic ideas. His sudden death from a brain haemorrhage prevented his completing this project.

Work
In St. Petersburg his most important research was in embryology. As early as in his doctoral thesis of 1759 he had recognised that every individual, both animals and plants go through a development from an egg to a grown individual. Wolff revived Harvey's doctrine of epigenesis – gradual building up of structures – challenging the prevailing theory that each organism develops from a homunculus – or tiny version of an adult – -inside a seed or sperm, the embryo being already preformed and encased in the ovary. Wolff proposed that groups of cells, initially unspecialized, differentiated into various tissues, organs, and systems. This view was later supported by the French pathologist Xavier Bichat (1771-1802).

In the cabbage and chestnut he observed the gradual formation of the leaf layers and the appearance of veins and petioles. This theory comes close to the germ layer theory of Karl Ernst von Baer (1792-1876). In establishing the blossom is a modified leaf, Wolff anticipated the theory of metamorphosis, formulated in 1790 by Johann Wolfgang von Goethe (1749-1832), according to which all the organs of a plant are the result of transformation of leaves.

Wolff's first works found little recognition among his contemporaries. His important work on the intestinal tract in chicks remained almost completely ignored. He reported that the organs arise from undifferentiated material. The basic potential nature and organisation of the structures of the organism are determined by the genetic constitution of the fertilised egg. The work was only rediscovered through Meckel’s translation, and was regarded by the embryologist von Baer as "the greatest masterpiece of scientific observation".

• Theoria generationis. Doctoral dissertation. Halae ad Salam (Halle an der Saale), lit. Hendelianis, 1759. German translation 1764.
• Theorie von der Generation in zwo Abhandlungen erklärt und bewiesen.
  Berlin, 1764; new revised and extended edition by Philipp Friedrich Theodore Meckel (1756-1803), Halle, 1774. Modern editions include that of Paul Samassa, in German, Ostwalds Klassiker der Exacten Wissenschaften nos. 84-85, Leipzig, W. Engelmann, 1896.
  (Philipp Friedrich Theodore Meckel, 1756-1803?)
• De formatione intestinorum praecipue, tum et de amnio spurio aliisque partibus embryonis gallinacei, nondum visis, observationes, in ovis incubatis institutae.
  Novi commentarii academiae scientiarum imperialis Petropolitaneae, 1768, 12: 403-507.
  Novi commentarii academiae scientiarum imperialis Petropolitaneae, 1769, 13: 478-530.
  Presented to the St. Petersburg Academy of Sciences in 1767, shortly after his arrival in Russia.
  Also in German translation by Johann Friedrich Meckel (1781-1833) as:
  
• Über die Bildung des Darmkanals im bebrüteten Hühnchen, übersetzt und mit Anmerkungen versehen. Halle, 1812.
  One of the acknowledged classics of embryology. Wolff's description of the formation of the chick's intestine by the rolling inwards of a leaf-like layer of the blastoderm was important as proving his theory of epigenesis. A German translation by Johann Friedrich Meckel (1781-1833) was published in 1812.
• De ordine fibrarum musculorum cordis. Acta academiae scientiarum imperialis Petropolitaneae, Tom. II; also in Nova acta, Tom I-XII.
• Von der eigenthümlichen und wesentlichen Kraft der vegetabilischen sowohl als auch der animalischen Substanz, als Erläuterung zu 2 Preisschriften.
  St. Petersburg, 1789.
• Objecta meditationum pro theoria monstrorum.
  Unfinished work published in Latin and Russian by A. T. Lukina, Leningrad, 1973.
• Alfred Kirchhoff (1838-1907):
  Die Idee der Pflanzen-Metamorphose bei Wolff und bei Göthe. Berlin, 1867. Caspar Friedrich Wolff. Sein Leben und seine Bedeutung für die Lehre von der organischen Entwicklung.
  Jenaische Zeitschrift für Medicin und Naturwissenschaft, Leipzig, 1868, 4: 193-220.
• W. M. Wheeler:
  Caspar Friedrich Wolff and the Theoria generationis.
  Biological Lectures. Marine Biological Laboratory, Woods Hole, Massachusetts, for 1898. Boston, 1899, pp. 265-284.
• Wilhelm von Waldeyer-Hartz (1836-1921): :
  Festrede. Sitzungsberichte der Preussischen Akademie der Wissenschaften, Berlin, 1904, 6: 209-226.
• J. Schuster:
  Caspar Friedrich Wolff. Leben und Gestalt eines deutschen Biologen.
  Sitzungsberichte der Gesellschaft naturforschender Freunde zu Berlin, 1937: 175-195. Der Streit um die Erkenntnis des organischen Werdens im Lichte der Briefe C. F. Wolffs an A. von Haller.
  Sudhoffs Archiv für die Geschichte der Medizin und der Naturwissenschaften, 1941, 34: 196-218.
• L. Stieda:
  Wolff, Kaspar Friedrich.
  In: Biographisches Lexikon der hervorragenden Ärzte. Volume V; Berlin-Vienna, 1934, pp- 983-984. With brief bibliography of secondary literature.
• B. E. Raykov:
  Caspar Friedrich Wolff.
  Zoologische Jahrbücher, Systematik, Ökologie und Geographie, 1964, 91: 555-626.
• G. Uschmann:
  Caspar Friedrich Wolff. Ein Pionier der modernen Embryologie. Jena, 1955.
• R. Herrlinger:
  F. Wolffs Theoria generationis. 1759. Die Geschichte einer epochemachenden Dissertation.
  Zeitschrift für Anatomie und Entwicklungsgeschichte, Berlin, 1959, 121: 245-270.
• Sherley A. Roe:
  The Development of Albrecht von Haller's Views on Embryology.
  Journal of the History of Biology, 1975, 8: 167-190. Rationalism and Embryology: Caspar Friedrich Wolff's Theory of Epigenesis.
  Journal of the History of Biology, 1979, 12: 1-43. Matter, Life, and Generation. Eighteenth-Century Embryology and the Haller-Wolff Debate. Cambridge, UK : Cambridge university Press, 1981. Paperback, 2002.
• Georg Schneider:
  Die Evolutionstheorie – das Grundproblem der modernen Biologie. Ein Abriß des Entwicklungsgedankens von Kaspar Friedrich Wolff über Darwin bis Lyssenko.
  Berlin, Deutscher Bauernverlag, 1952.
• I. Jahn:
  Wer regte Caspar Friedrich Wolff (1734-1794) zu seiner Dissertation "Theoria generationis" (1759)?
  Philosophia Scientiae. 1997, Volume 2, Cahier spécial 2 : "Themen zur Geschichte der Biologie - Zum 60. Geburstag von Professor Dr. Armin Geus".