Results found: 2

Search results

Search:
in the keywords: SPONTANEOUS GENERATION

Sort By:

Limit search:

Caspar Friedrich Wolff (1734-1794). The concept of epigenesis and the problem of spontaneous generation

100%

Bednarczyk A.

Kwartalnik Historii Nauki i Techniki

2005

vol. 50

issue 3-4

59-86

The link between the notion of epigenesis and that of spontaneous generation does not seem complicated when it is viewed in theoretical terms or when it is approached in a pure model form. However, once any of its particular manifestations in the history of biology is analysed, the interrelationship between the two notions ceases to be unequivocal. One example of that comes with the first fully-fledged concept of epigenesis, based on careful observation of embryonic development, presented by Caspar Friedrich Wolff in the 18th century. The process of development that an act of spontaneous generation has given rise to cannot, of course, be anything else but one of epigenesis. In this sense, epigenesis constitutes a necessary condition for spontaneous generation, but is not a sufficient condition, i.e. not every process of development through epigenesis has at its source an act of spontaneous generation. Evidence that Wolff was inclined towards the concept of spontaneous generation comes from the presence in his works of a notion described by the Latin term 'ortus' (emergence). That notion - together with that of an organic body - is subject to detailed analysis in the current paper. If the process of spontaneous generation is understood as a process of emergence in nature of what is animate and organic, from what is inanimate and non-organic, and as a process in which living beings are not involved, but a living being is its outcome, then the notion of 'ortus' is close in meaning to the notion of spontaneous generation. However, the deistic and theological philosophical foundation of Wolff's concept of epigenesis is in conflict with the notion of spontaneous generation. It seems that Wolff's notion of 'ortus' can be interpreted in two ways. Firstly, it can be interpreted as as result of the theoretical extrapolation in time applied by Wolff to the usual way in which organic bodies emerge (the process is always given rise to by a non-organic body, supplied by another organic body), all the way back to that the distant moment when the first organic body in time was to emerge; this extrapolation has been reconstructed in detail in the current paper. Secondly, the notion of 'ortus' can be also interpreted as a special kind of heterogenesis, a process which is given rise to by an organic body, but which produces living beings that do not deserve the name of organic bodies - beings that are poorly differentiated in terms of morphology and organization, and thus devoid of distinct species membership, such as simple algae, moulds, internal parasites etc. If that is a correct interpretation, then in neither case would Wolff's ideas have anything to do with real spontaneous generation in the strict sense.

PETER SIMON PALLAS (1741-1811). THE STRUCTURE OF THE ORGANIC WORLD AND THE NOTION OF SPECIES. ON THE BICENTENARY OF HIS DEATH (Peter Simon Pallas (1741-1811). Struktura swiata organicznego i pojecie gatunku. W dwusetna rocznice smierci)

63%

Bednarczyk A.

Kwartalnik Historii Nauki i Techniki

2010

vol. 55

issue 2

An attempt has been made in the current paper to dispel two myths concerning Peter Simon Pallas, myths which have led historians of biology to distort the picture of some of the general biological ideas developed by that eminent naturalist of the Age of Enlightenment. The first point dealt with in the paper involves the myth that Pallas had allegedly drafted a 'tree of life' diagram, one of the many graphic representations of this kind to appear in later times, illustrating the structure of the organic world. The tree, of which Pallas merely left a short description (but not a depiction), took - in the articles of authors who wrote about it - a variety of graphic forms (largely dependent on the authors' pictorial inventiveness), with all the authors assuring the readers that they illustrated their reasoning with the help of Pallas's tree of life, but never mentioning that it was they themselves who had drawn it. The current paper presents a juxtaposition of a number of such diagrams, drawn by different authors: the great diversity of the diagrams is sufficient proof that the existence of one, original 'Pallas tree' is just a myth. Another aspect of the myth has to do with the view that the tree supposedly illustrated phylogenetic dependencies - in fact, Pallas described affinity relationships between groups in the animal world. The present paper investigates how the 'tree of life' myth has developed, and reveals the mechanism that has most likely led to the myth being perpetuated in writings on the history of biology. The second issue discussed in the current paper relates to the myth of how Pallas's general views on biology allegedly evolved. The naturalist was supposed to have moved from transformism (characteristic of early stages of his work) to the idea of the immutability of species, formed in the period of his full scientific maturity. The current paper proves, inter alia on the basis of little known and not easily accessible writings by the scholar, that Pallas espoused the Age of Enlightenment's deism, an important element of which was the idea of the immutability of species, to which Pallas steadfastly subscribed. On the other hand, the analysis presented in the paper has revealed that Pallas seemed to consider the problem of species on two planes: that of free-roaming wild species, which remained absolutely immutable, and that of domesticated species, which did manifest some mutability, largely sustained by human effort but never transgressing species boundaries. It was also - and only - under domestication that monsters appeared. Pallas did contemplate, not without much hesitation, teratogenesis as a possible mechanism behind speciation, but - given the lethal character of monstrous modifications - he did not treat it as the real mechanism of speciation.

Refine search results

2 Kwartalnik Historii Nauki i Techniki

2 Bednarczyk A.

1 2010

1 2005

Search results

Caspar Friedrich Wolff (1734-1794). The concept of epigenesis and the problem of spontaneous generation

PETER SIMON PALLAS (1741-1811). THE STRUCTURE OF THE ORGANIC WORLD AND THE NOTION OF SPECIES. ON THE BICENTENARY OF HIS DEATH (Peter Simon Pallas (1741-1811). Struktura swiata organicznego i pojecie gatunku. W dwusetna rocznice smierci)