GOOD MICROSCOPICAL OBJECTS
3.4. A genealogy for the green fly
In addition to natural history where he had proposed corrections to his previous theory on the hermaphroditism of the coccus, Breyn took the opportunity of proposing a general question concerning parthenogenesis, which was expressed as follows:
“PHYSICAL QUESTION. Could it be possible to demonstrate in an indisputable way, that among the natural things, there existed a truly androgynous species of animal? Say, could it be possible that such a species propagates only through eggs which appear but to be fertilised by themselves, and without any support from the male of the same species?”.374
371 Baglioni 1940, 70.
372 Recent works furthermore show that Redi took only a small part in the active experimentation and observation of nature, and, as a court physician, his role was much more that of leading a programme for which the grand Duke of Tuscany had offered him all suitable means (Bernardi 1999, 14-15, 28-30;
Guerrini 1999, 52). According to Baglioni (1940, 26-30), Cestoni contributed to the main discovery of the generation of the insects through the eggs traditionally ascribed to Redi.
373 See Ruestow (1996, 215, 220-222; 1984, 246-248) on the tension between the solitary and the social behavior of Leeuwenhoek.
374 Breyn 1733b, 28. The problem was asked as follows: “PROBLEMA PHYSICUM.An indubitate demonstrari possit, in rerum natura genus aliquod animalium vere androgynum, id est, quod sine
Many consequences stem from Breyn’s research. First, after forty years of investigation on small insects, no hermaphroditism could actually be considered to have been
established, though Cestoni and Garidel had maintained that lice were hermaphroditic.
Indeed, no experiments had been carried out on parthenogenesis, but only observations.
Second, the tradition of natural history had established itself as a judge of previous works and their value for increasing understanding of such a topic, and Leeuwenhoek’s works were discarded.375 Third, Breyn’s question hid one of the historical dimensions that had for a long time accompanied the issue, i.e. the topic of the ambiguity of organisms. Highlighting the parthenogenetic issue contributed to putting aside the question of ambiguity. Fourth, the microscope was acknowledged hereto as an tacit routine tool for such research. Breyn’s study positively created a visible framework for the democratic microscope, and defined not only a type of object but also a range of phenomena that the microscope, along with other techniques, had helped to bring to the forefront.
Public reaction to Breyn’s thesis soon appeared which welcomed these ideas, regardless of the means, and the advancement of insect research came to be known everywhere.
This was acknowledged for instance in a review of Massuet and Rousset de Missy’s research on the worms that destroyed the sea wall of Holland in the 1730s. To the question of how did these worms reproduce, a writer in Journal de Trévoux replied in 1734 : “We can not consider that, in order to answer such a question, we should resort to the unproved system of the two sexes gathered in one animal to multiply itself
without mating. Thus we guess it is much simpler to say that these worms first mate and then lay their eggs somewhere”.376 An additional major indication demonstrating that Breyn’s research was topical is that after his 1733 book, publication on insects and on parthenogenesis increased a lot. In 1734 Johann Leonhard Frisch (1666-1743), who had
adminiculo maris sui generis, ova in et a se ipso foecundata parere, adeoque solum ex et a se ipso genus suum propagare possit?”.
375 That is also a reason why the primacy claimed by van Seters (1962, 99) of Leeuwenhoek on the viviparity of lice can not be considered relevant.
376 An. 1734, 501-502.
been working in Berlin for 14 years on insects, observed mating in lice;377 the same year, Cosmus Conrad Cuno in Augsburg published his Observations on the
microscopical structure of insects,378 and, in the early 1740s, August Rösel von
Rosenhoef (1705-1759) in Nuremberg began the publication of Monthly entomological entertainment, a journal which lasted until 1761. Also in 1734, Réaumur launched a synthesis of the previous research on insects and right from the first pages of the huge Mémoires pour servir à l’histoire des insectes, he reminded the reader that cochineal and Kermes had been proven definitely to be insects.379 The next two steps in the study of parthenogenesis are much better known than the above and I will not insist on them here.380 Réaumur tackled Breyn’s question with an experiment of isolating a louse in 1735 in order to observe whether absence of mating would lead the green fly to have offspring. The protocol was based on a previous experiment reported to the academy by C.-J. Geoffroy, who in 1724 had established the viviparity of the louse. When enclosing a louse freshly taken from an elm-gall under a glass bell, he discovered they could breed directly without eggs.381 Geoffroy thus provided an important element for Réaumur’s and Bonnet’s subsequent experimental protocol, because the entire demonstration of parthenogenesis required the control of presence or absence of a previous mating of the insects, which was supplied by this procedure. Nevertheless, even when the absence of mating was assured, Réaumur’s green flies died before laying their offspring so that he could not observe parthenogenetic phenomena. When Charles
377 van Seters 1962, 99.
378 For an account of Cuno’s microscopical observations, see Geus 1976, 133-134.
379 Réaumur 1734 I, 5-6. Five methodologies were synthesised in Réaumur’s comprehensive works, systematics, microanatomy, physiology, the study of behaviour, and drawing. This work discussed ideas of a comprehensive range of scholars (Aldrovande, Mouffet, Swammerdam, Goedart, Mérian, Redi, Malpighi, Leeuwenhoek, Vallisneri, etc.). Some of Réaumur’s Mémoires are constant colloquy with particular authors. Réaumur’s Mémoires --about 80 mémoires published-- are a heuristic and selective synthesis of the knowledge and methodologies of insects. Selective because he sorted much information out, rejecting with further observations not only Pliny or Goedart’s “tales”, but even, after Vallisneri, Redi’s belief that the gall-insects came from a vegetable (Réaumur 1734 I, 31; see n13) Every previous assertion on insects was filtered by Réaumur with the sieve of systematic observation and experiments, which provided a base for many subsequent naturalistic studies.
380 On the relation between Réaumur and Bonnet, and on the latter’s experiment on the parthenogenesis of green fly, see Roger 1993, 281; Dawson 1987, 77-81.
381 Geoffroy 1726, 323.
Bonnet started corresponding with Réaumur in 1737, the French Academician left the issue in the young man’s hands who, in 1740, succeeded in observing parthenogenesis on several species of louse.382 The following table provides a genealogical trajectory of the problem of the parthenogenesis.
Table 1. Genealogical trajectory of the parthenogenetic problem
Date 1660 1680 1700 1710-14 1724-30 1735 1740 1750
Redi-> Cestoni-> Cestoni-> ->Vallisneri->Breyn-> ->Réaumur->->Bonnet->
->Marsigli ->Bazin
->La Hire-> ->La Hire ->Geoffroy->Geoffroy ->Trembley
Swammerdam383 ->Leeuwenhoek Ruysscher-> Lyonet
Strobelberger Albrecht?384 ->Frisch
Two things characterise the change after Breyn’s clarification of the question: the systematic recourse to experimentation with Réaumur, and the standard use of the microscope. Rejection of Leeuwenhoek by the entomological tradition was nevertheless softened by Réaumur who continued to quote him, as he used to quote everyone who had previously done research on objects he investigated. Contrary to the discontinuous vision of the history of parthenogenesis given by historians,385 the issue went through many steps between Leeuwenhoek and Bonnet, and crossed four final important episodes --Geoffroy, Ruysscher, Breyn and Réaumur’s works-- that had further
ramifications for subsequent discoveries. By introducing the microscope into the court
382 For a detailed account of Bonnet’s research, see Buscaglia 1994, 289-292 and Dawson 1988, 197-200.
383 On Swammerdam, Bonnet (1781[1764] II, 375) indicated that there were no proofs that the louse was androgynous, even after Swammerdam dissected 40 of them. Is it necessary to say that Cestoni, Breyn and Ruysscher had been ignored by Wilson, Fournier and even Ruestow, to show that the origin of parthenogenesis, its relation to the microscope and its influence on its use have been ignored by historians of microscopy? For an account of the genealogy of the discovery see van Seters 1962, 98-104.
384 On Albrecht from Hildesheim near Hanover, see Baker 1952, 19.
385 Fournier 1991, 171; Dawson 1987, 16-18.
of law, Ruysscher established both the absence of the ambiguity of cochineal and credited the microscope with being suitable for research. A further step in Breyn’s work was to ask whether true hermaphroditism could be found in nature, a question that
“forced” Réaumur to enter into the experimental arena on lice, using Geoffroy’s procedure. The problem was then offered to Bonnet, and for this he had always in fact been grateful to Réaumur. The discovery of parthenogenesis by Bonnet crowned seventy years of intensive research and synthesised works of entomological traditions coming from several countries. Bonnet completed the circle by referring to Redi, Malpighi, Vallisneri and Réaumur, and to Breyn’s problem in the 1745 Treatise on Insectology, saying that it was after the work of Réaumur that he succeeded in finding a positive solution.386 Actually Réaumur never ceased to argue in favour of the
democratic microscope, encouraging young scholars to observe and to reveal their methods, as in a 1746 letter to Pierre Lyonnet: “You will be of a great help to those who observe and draw with the microscope, when you will teach them how to get rid of the gear some believe is necessary. You say things so interesting in your letter that I should not dare showing that I would have been charmed to read the method by which you simplify the use of the microscope”.387
Contrary to what has been written by historians,388 up to the 1730s the ex ovo omnia was thus not admitted as the general paradigm, mainly because some exceptions were always to be found for numerous species. The seeds of fungi were dubious, as were the seeds of coral, considered a plant;389 several cryptogam, like mosses and nostoc, still had no seeds, lice and green flies seemed to present a different way of generation; the first experiment of the regeneration of a millipede had been performed by an
anonymous scholar, probably Puget, in 1706; viviparity of lice had been established.
Bourguet considered in 1722 that “there is an almost infinite number of insects and
386 Bonnet 1745, viii-xi, 99-100.
387 Réaumur to Lyonnet, the 13th of January 1746 (BPU: FT 5, f° 159v).
388 Wilson 1995, 203.
389 Marchant 1714, 106-107; Réaumur 1729, 272. On coral, see chapter 5.1, 5.3.
other animals that leave on the earth and in the sea, of which each individual produces his own kind, with no distinction of sex”.390 The only general rule was the preexistence of the germ, as opposed to spontaneism and transmutationism. The demonstration of a method for generation close to that of seeds for the fungi proven by Micheli in 1729, and the synthesis of the parthenogenetic issue by Breyn allowed the reorientation of the entire subject of the generation of cryptogam and insects, by raising the level of the standard required to study these subjects. When Breyn expressed his famous
parthenogenetic question, he hardened and extended the preexistentialist value of ex ovo omnia, which consequently required henceforth the passage to experimentation as a key step. This is the reason why, only from 1730, did ex ovo omnia become more visible, after a period of competition with the preexisting model.
The status acquired by the microscope through this period of research was actually not the same as the great visibility that existed before the 1690s. The routine use of the instrument, present in every one of these papers, was not in fact questioned at all.
Considering the importance of the naturalistic problems dealt with, mainly involving hermaphroditism and the exception to the general rule it could provide, they credited the microscope with the status of a research tool, acknowledged by everyone though never highlighted. This trend was echoed by a new small-scale if not microscopical object, insects and seeds, defined and shared at least by all academics and scholars. The lower visibility of the microscope from the beginning of the century corresponds to its new routine status, and explains why historians have not found microscopes in this period. Indeed it belongs to the area where practices cross disciplines. In a sense, this was the period of microscopists without microscopes, for microscopes were never emphasised in the research, though they were often included in both the iconographic and demonstrative strategies by scholars. This was no longer the time of the surprising marvels the microscope had revealed before the astounded public eye of seventeenth-century observers. Marvels were, for a certain time, better controlled staying within the
390 Bourguet 1729, 78.
arena of academies. But there would not be much time to wait before new marvels would appear through the ocular. Réaumur indeed revealed in the 1742 sixth volume of Mémoires the existence of a strange microscopic animal that had the ability to fully regenerate after being cut.391 As we will see in chapter 5, the polyp soon would enter into science and public life.
391 Réaumur 1742 VI, xlix-lv.
CHAPTER 4.PRODUCTION AND VISIBILITY OF MICROSCOPES IN THE EIGHTEENTH
-CENTURY.
4.1. Changes in visibility in the European market of the microscope in the first