Caspar Friedrich Wolff
Caspar Friedrich Wolff (* 18th January 1734 in Berlin , † March 5 (according to the Julian calendar: February 22 ) in 1794 in Saint Petersburg ) was a German anatomist , physiologist and botanist and one of the founders of modern Embryology (theory of evolution) and histology (Tissue theory). Using microscopic examinations of plants and animals, he was able to refute the view of the preformation theory of embryos and show how they develop during embryogenesis .
biography
Early years and education
Caspar Friedrich Wolff was born in 1734 as the son of master tailor Johann Wolff and his wife Anna Sophie Wolff. Stiebeler born in Berlin. With Christian Friedrich (born 1728), Anna Sophia (born 1732) and Maria Elisabeth (born 1732) he had three older siblings. His father came from Prenzlau and had settled in Berlin and acquired civil rights.
Almost nothing is known about his youth, all we know is that in 1753, at the age of 19, he attended the Berlin Collegium medico-chirurgicum , the military medical training center of the Royal Academy of Sciences in Berlin. Here various full members of the Academy taught the students and offered courses in surgery , anatomy , microscopy , chemistry and botany . Among them were some of the most famous researchers of the time, such as Peter Simon Pallas , Johann Friedrich Meckel , Johann Gottlieb Gleditsch , Johann Nathanael Lieberkühn and Johann Heinrich Pott . Before Wolff began studying, Pierre-Louis Moreau de Maupertuis was the director of the academy, who was known not only for an expedition to Lapland to measure degrees at the North Pole but also for his writings on the development of germs in animals. He spoke out against the theories according to which the embryo and thus the offspring are preformed (preformed) in the mother's egg (according to the theory of the Ovists) or in the father's sperm (according to the theory of the animal culists). He himself researched the inheritance of deformities , especially toe anomalies in chickens and dogs and six-fingeredness in a Berlin family, as well as about bastards in the animal kingdom. The spontaneous generation theories put forward by Georges-Louis Leclerc de Buffon and John Turberville Needham could not explain the conception for him and he encouraged intensive microscopic research to clarify this question. Maupertuis left Berlin in 1752, but his writings continued to be popular and also inspired Caspar Friedrich Wolff in his studies.
In 1755 Wolff went to the medical faculty in Halle and worked there under Andreas Elias Büchner , the dean of the university and president of the German Academy of Natural Scientists Leopoldina , on his dissertation entitled Theoria generationis , which he completed on November 28, 1759. It is not known whether Büchner actually supported him in his work or whether it was developed under a Berlin doctoral supervisor, as no name is given in the dissertation. He was influenced in any case by the physician Philipp Adolph Böhmer , who, like Wolff , advocated the development of germs from simple tissues ( epigenesis ), as well as by Heinrich Christian Alberti , who regularly conducted botanical lectures and excursions. In his work, Wolff presented the embryonic development of plants and animals on the basis of microscopic examinations. He also formulated a theory according to which the development of new organs during embryogenesis occurs through an "essential force" which he does not name, but does is responsible for the nutritional processes of the organisms. In doing so, he contrasts his theory of the development of the embryo from relatively undifferentiated tissue with the theory of preformation, according to which all structures should already be contained in the germ. His work was recognized by both supporters of a similar view and a number of critics of epigenesis.
Career entry and early teaching
After Wolff received his doctorate, he tried to get a job as an academic teacher and applied to various universities, including the one in Bützow and the one in Rinteln . Towards the end of the year, the mathematician Leonhard Euler , who was a good friend of Maupertuis' and deputy director of the Berlin Academy of Sciences, recommended Wolff for a professorship at the University of Saint Petersburg . He described Wolff as a young man:
- “Which is excellent for the Kaiserl. Academie would send. The same person seriously has no tendency to practice Medica, but lays solely on studying and experimenting. " (After Jahn 2001, p. 102)
However, since Prussia and Russia were at war at the time, Wolff was not yet called to Saint Petersburg at that time. Instead he served from 1761 to 1763, until the end of the Seven Years' War , as a military doctor in the field hospital in Breslau for the Prussian army. Here he was released from field service by the chief field doctor Christian Andreas Cothenius due to his knowledge and was supposed to give lectures on anatomy to the field surgeons. In 1763 the field hospital was closed. The first biographical description of his work by Christian Ludwig Mursinna , whom he trained here and who later became his assistant, comes from this time . Mursinna, who became professor at the Collegium medico-chirurgicum and surgeon at the Charité from 1787 , portrayed Wolff as a very good teacher:
- “Therefore all surgeons were able to enjoy the most fruitful lessons, which soon all field and city doctors took part. Wolff had such a neatly clear, logical lecture that everyone could easily understand it and learn more or less thoroughly, as the monthly exams testified. " (After Jahn 2001, p. 103)
Wolff had already applied to the Collegium medico-chirurgicum in Berlin in 1762 to be allowed to give lectures. The Collegium rejected the application because it would have presented a special regulation against the premise that only ordinary members of the Academy were allowed to give lectures. Cothenius, who was dean at the Obercollegium Medicum at that time , subsequently granted Wolff permission to hold private lectures. Wolff did this very successfully for four years, even though, unlike the professors at the Collegium, he had to bear the costs for his demonstration objects and the room rent himself. This success was a thorn in the side of some professors; they and their students became sharp critics of Wolff's teaching methods.
During this time, too, Wolff's research concentrated very much on the observation of embryonic development, which he carried out on chicken embryos. In doing so, he succeeded in depicting the processes that later led to his publication “About the formation of the intestinal canal in incubated chickens” . For this work he was in constant contact with Albrecht von Haller , who rejected the epigenesis theory, but showed great interest in Wolff's work. The benevolence changed after a publication by Wolff in 1766, which was very polemical against the preformation theory and above all against a publication by Charles Bonnet against the epigenesis. Albrecht von Haller presented his opinion on Wolff's theories with a clear sentence in his textbook "Elementa physiologiae corporis humani" : "nulla est epigenesis" (in German: "There is no epigenesis" ). He justified this definition with the fact that nothing could arise out of nature, i.e. through epigenesis, since it was created by God. Wolff reacted to this with confusion, since on the one hand he believed his Epigenesis theory to be correct, on the other hand the arguments of Haller's words were weighty. He wrote:
- "That I almost don't know what to do in the future with regard to the development of generation theory." (After Jahn 2001, p. 106)
At the same time, Wolff was offered a chair as professor of anatomy and physiology in Saint Petersburg and was invited to become a member of the local Academy of Sciences. Wolff accepted this offer and arrived on May 15, 1767 in Saint Petersburg. He did not continue his embryological work in Saint Petersburg, but published his results on the formation of the intestinal canal there for the first time in 1769.
Research and teaching activity in Saint Petersburg
In Saint Petersburg, his work and responsibilities were mainly in the administration of the Anatomical Cabinet, the Anatomical Theater and the Botanical Garden of the Academy of Sciences. However, very little is known about his professional and family life from this period, as there are neither autobiographical notes nor descriptions from colleagues or friends. According to Mursinna, shortly before leaving for Saint Petersburg, he married a handsome woman whose name is unknown. With this and their three children Louisa , Maria and Karl , Wolff lived relatively withdrawn on the Vasilevsk Island and devoted himself almost exclusively to work.
As an anatomist, Caspar Friedrich Wolff had, among other things, the task of dissecting corpses that were found by the police and was supposed to show the circumstances of death. He used this work for anatomical studies and compared the results with those he made when dissecting dead lions and tigers in the court zoo. Furthermore, he examined anatomical malformations ( freak births , "monsters" in his day) that were present in the anatomical collection as alcohol preparations and that were also made available to him as fresh preparations for the collection by the country's doctors on imperial instructions. Wolff not only worked scientifically on the preparations, he also tried to capture the aesthetics of the anatomy. He wrote:
- “There is no doubt that the intestines also have their own true and non-apparent beauty. I saw the interiors of some monsters with such astonishing grace and elegance that I have no doubt that the nature which created these bodies must also have set itself the beauty of the structure as its goal. Even in the most general internal organs of our body there is a remarkable beauty that is easier to track down than to express with words. " (After Jahn 2001, p. 107)
Through the research on the deformities, a conflict between the preformists and the representatives of epigenesis, already mentioned by Maupertuis, was touched upon, which Wolff had already mentioned in his dissertation: The training of the monsters could not correspond to the will of the creator god. Wolff had the unique opportunity in St. Petersburg to examine a collection of 42 monsters and wrote extensive manuscripts for them. Around 1,000 handwritten pages on this subject were found in his estate, along with 52 panels he had drawn. On about 100 pages Wolff presented his theories about the formation of the monster:
- "The monsters do not come from God, but are a matter of nature, which has failed to succeed." (Wolff 1773, after Jahn 2001, p. 108)
The work of Caspar Friedrich Wolff in Saint Petersburg was hardly noticed in Europe; on the other hand, Wolff followed the discussion about epigenesis with interest, and above all the work of Johann Friedrich Blumenbach , who succeeded Albrecht von Haller in Göttingen from 1777. Like Wolff, Blumenbach was convinced of the epigenesis and is now considered to be the one who brought about the breakthrough of the epigenesis over the preformation theory in research.
Caspar Friedrich Wolff died of a stroke on February 22, 1794 in Saint Petersburg.
Work viewing
Caspar Friedrich Wolff was considered a good observer during his time in office. However, attempts to explain his observations through the theory of epigenesis were largely rejected. They contradicted the theory of preformation, which was widespread and accepted in the 18th century, and were even viewed as incompatible with the belief in divine creation . Wolff was not the first scientist to deny the preformation, but he was the first who, with his fully formulated theory of epigenesis, confronted it with a serious alternative that was based on direct observation.
The dissertation Theoria generationis
This contrast in the assessment of his work first appeared with his dissertation Theoria generationis, written in Latin in 1759: While he himself attached great importance to his conclusions and explanations for the development processes described in plants and animals, the work of science was above all due to the very good microscopic work and the careful representation of what has been seen.
In the first part of this work, Wolff describes in detail the development of plant seedlings from simple germinal tissues and "vesicles" ( cells ) to more complex plants. According to his description, larger structures, canals and vessels develop through the absorption of fluids ("nutritional forces"), followed by solid structures such as walls, stems and leaf veins through evaporation . He also describes in detail the formation and formation of flower parts and leaves as well as the formation of fruits and seeds . The stalks of the broad bean ( Vicia faba ) and the pulp of apples and pears , in which he could make out both juice-filled cells and ducts, served him as objects . He described the growth on the stems, leaves and flowers of cabbage and chestnuts , and in his investigations he could not discover any prefabricated and rolled-up structures as required by the preformists. Instead, he found points of vegetation , which he described as punctum sive superficies vegetationis and from which the newly growing structures developed. He was also able to observe the fertilization by the pollen and described this as "delivery of a perfect food" , which causes new growth and the formation of an embryo.
In the second part of this thesis he describes in detail the embryonic development of the chicken embryo, which develops from a simple germinal disc on the yolk into a fully developed chick. According to his observation, all visible organs develop from the blood vessels to the heart and kidneys to the intestines, to which he later devoted another, more detailed work. In his observations he recognized parallels between the development of plants and animals, which he tried to explain through his principles of "procreation". In the third part of the thesis, he accordingly formulated the general educational laws for the development of organisms through the “nutritional force” (“essential force”) for growth and the “solidification ability” for organ formation, which can also cause deformities.
Albrecht von Haller, in particular, described the Theoria generationis as an important work, although he rejected the Epigenesis theory presented in it, and it is assumed that many scholars already dealt with it during Wolff's lifetime. In 1774 the Berlin doctor Philipp Friedrich Theodor Meckel had the work reprinted and Johann Friedrich Blumenbach also cited it in his works.
The theory of the generation
In 1764, The Theory of the Generation, an extension of the dissertation in German followed, in which he primarily addressed the questions of his acquaintances and friends and again presented his theories in an understandable manner and with examples. The first version appeared only in handwritten form for his acquaintances, after starting his teaching activity in Berlin he also published the work to make it accessible to his students.
In an introductory part, Wolff explained the terms “anatomy”, “physiology” and, in particular, his understanding of the term “generation”, presenting a historical outline of Aristotle up to his own time. The most important section of the work, however, is a justification of his epigenesis theory to the representatives of the preformation theory, and he answered in detail, sometimes clearly polemical , to the criticisms made by Albrecht von Haller and Charles Bonnet of the epigenesis. At the center of this essay is the thought that nature itself is capable of bringing about an abundance of changes.
In the second part of the theory of the generation , he repeats the results of his dissertation, becoming clearer in the areas questioned and, above all, in the development of animal organs and in what he calls “conception”. In this part he regularly presented parallels between the development of plants and animals and highlighted their similarities. He also described the structure of both plants and animals on the basis of three organizational levels: the "vesicles" or cells that form the simple parts, the structures made up of tissues such as the pulp of plants or the muscles of animals, and the more complex organs. According to Wolff's theory, the structures develop apart, either through "excernation" (structures are formed by other structures) or through "deposition" (structures are combined with other structures to form new ones). He believed (in contrast to the theory of the multiplication of cells that emerged in the 19th century) that all structures develop from a previously unorganized germ mass in which no structures are yet present. In his opinion, the “concept”, ie the plan for the differentiation of living beings, arises from the addition of a new nutrient substance, the pollen in plants or the sperm in animals.
De formatione intestinorum
To this day, Wolff's main work is considered to be his treatise on the formation of the intestinal canal in incubated chickens, which appeared in Latin under the title De formatione intestinorum in his first year in Saint Petersburg, 1769. This representation was so detailed that it was long considered one of the most important works in the field of nature observation.
To support his Epigenesis theories, he closely observed the development of the chicken by taking eggs with a precisely known incubation time at regular intervals and analyzing them under the microscope. The result was a series of pictures and descriptions that for the first time described an organ in its development from the first plant to the complete formation and was able to trace it back to a leaf-like germ mass, which was incorporated into the cotyledon theory of Christian Heinrich Pander in 1817 and its refinement by Karl Ernst von Baer flowed in 1828. In his account of the evolution of animals from 1828 it says:
- "Wolff first recognized this method of development and fully explored it in the greatest masterpiece that we know from the field of observational natural sciences." (After Jahn 2001, p. 113)
The work was even more widely distributed in 1812 when it was reprinted in German by Johann Friedrich Meckel the Younger .
Working in Saint Petersburg
While the work in Saint Petersburg was as solid as the treatises on embryonic development and epigenesis, it had very little impact on the science of the time and subsequent generations. During this time he mainly described the anatomy of humans and various zoo animals as well as various deformities of humans. This work was also very thorough, especially his depictions of the muscles and the heart. He linked the research on the deformities with the work he had already done during his dissertation and continued to try to find the force that could have caused these changes (the "essential force") and also wrote an award for the best paper on this subject. As a result, he published the contributions of Johann Friedrich Blumenbach and Ignaz von Born in 1789 , which he assessed as outstanding, and added his own thoughts on the Vis essentialis .
Wolff's unpublished documents about the deformities that Ernst von Baer found in his estate and presented to the scientific public for the first time in 1847 are considered a special discovery. In these writings it becomes clear that Wolff, on the one hand, had thought about the individual development and the origin of the deformities, on the other hand, the main features of an inheritance theory can be recognized in the writings. For example, he explained the six fingers as an "organization that suddenly appeared" that is passed on to the descendants. In addition, he assumed a constancy of characteristics, which he called materia qualificata , and which must change before the individual changes (corresponds to today's mutation ). To this day, however, these writings have not been fully cataloged.
Effect after his death
Although Caspar Friedrich Wolff must be regarded as one of the most important natural scientists of his time, there are hardly any records of his life that go beyond the scientific writings. Ernst von Baer made the first systematic compilation of biographical material when he presented Wolff's unknown manuscripts in 1847.
Wolff received literary appreciation in 1817 from the poet and naturalist Johann Wolfgang von Goethe , who printed Wolff's texts on plant development together with his own treatise Metamorphosis of Plants in the first edition of his Morphological Notebooks . Caspar Friedrich Wolff's renewed memory of Mursinna was then printed in the second issue .
Wolff's writings became more widely known through the printing of his work On the Formation of the Intestinal Canal in Incubated Chickens in German, especially since, together with Goethe's publications in 1817, the research of embryonic development through the contributions of Pander and Baer once again came to the fore Interest. In 1840, Wolff's theories were finally included in the Handbuch der Physiologie des Menschen by Johannes Müller and became internationally known. After Caspar Friedrich Wolff, various structures were named in this work, which he described for the first time during his work and whose names are still valid today. The best-known of these discoveries is the Wolff Gang ; the mesonephros is also called Wolff's body .
Publications (selection)
Caspar Friedrich Wolff has published around 40 publications in his academic career, most of which appeared in the newspapers of the Royal Academy of Sciences in Saint Petersburg. The following titles represent a selection:
- Theoria generationis , Halle 1759 (German translation: Ostwald's Classics of Exact Sciences Volume 84/85, Leipzig 1896, reprint 1999)
- Theory of the Generation, explained and proven in two treatises , Berlin 1764 ( digitized and full text in the German Text Archive )
- De formatione intestinorum , Saint Petersburg 1769
- De leone observationes anatomicae , Saint Petersburg 1771
- On the peculiar and essential power of both vegetable and animal substance, as an explanation of two price papers on the nutritional power , Saint Petersburg 1789
- Explicatio tabularum anatomicarum VII, VIII et IX , Saint Petersburg 1801
- On the formation of the intestinal canal in incubated chickens , Halle 1812
literature
- Werner E. Gerabek : Wolff, Caspar Friedrich. In: Werner E. Gerabek, Bernhard D. Haage, Gundolf Keil , Wolfgang Wegner (Hrsgg.): Enzyklopädie Medizingeschichte. De Gruyter, Berlin / New York 2005, ISBN 3-11-015714-4 , p. 1502 f.
- Ilse Jahn : Caspar Friedrich Wolff . In: Ilse Jahn, Michael Schmitt (eds.): Darwin & Co. The history of biology in portraits . CH Beck, Munich 2001. ISBN 3-406-44642-6 (2 vols.)
- Ilse Jahn: history of biology. Theories, methods, institutions, short biographies . Nikol VG Spectrum, Hamburg 2004, ISBN 3-937872-01-9
- Richard Toellner (Hrsg.): Illustrated history of medicine . Bechtermünz Verlag, Augsburg 2000, ISBN 3-8289-1875-1 (6 vols.).
- Georg Uschmann : Caspar Friedrich Wolff. A pioneer in modern embryology. Leipzig u. a. 1955.
- Ernst Wunschmann: Wolff, Kaspar Friedrich . In: Allgemeine Deutsche Biographie (ADB). Volume 44, Duncker & Humblot, Leipzig 1898, pp. 41-43.
Web links
Remarks
| personal data | |
|---|---|
| SURNAME | Wolff, Caspar Friedrich |
| BRIEF DESCRIPTION | German physiologist and founder of modern embryology |
| DATE OF BIRTH | January 18, 1734 |
| PLACE OF BIRTH | Berlin |
| DATE OF DEATH | March 5, 1794 |
| Place of death | St. Petersburg |