Geología

Although in 1718 it gave rise to the first French treatise of m icroscopical research, the work of Louis Joblot (1645-1723), published in Paris with the title Descriptions et usages de plusieurs nou veaux microscopes, tant simples que composés was seldom discussed by historians. Historiography for Joblot is both poor and dated, especially if compared with historiography for Leeuw enhoek and Malpighi. In 1895, Konarski claimed a pre-em inent place for Joblot in the history of protozoology, attesting that he had

discovered their contractile vacuole. O udem ans later show ed that Joblot also described the parasitic nymph o f the pond M u sse l.^

However, the biographer of Leeuwenhoek, Clifford D obell strongly defended L eeuw enhoek’s primacy going as far as to consider that Joblot had im itated him.^ Jo b lo t’s book was ignored by Jacques Roger, who, in 1963, integrated him into the context of the growing quarrel o f anim alculism against o v ism .^ A ccording to Roger, Joblot show ed the spermatic animalcules^ to some Italian and French physicians. M ost likely, Roger has found evidence for this but did not quote his sources, and actually such interest in spermatic anim alcules does not stem at all from the 1718 treatise. N owhere is there mention of the spermatic animalcules. Even the term “anim alcule” is absent; Joblot always uses “anim als” , “fishes” and sometimes “insects” to name the animalcules of infusionss. Van der Pas in his biographical entry for Joblot, in DSB, and more recently Fournier, have driven attention to Jo b lo t’s antispontaneist e x p e r i m e n t s .^ Descriptions et usages de plusieurs nouveaux

m ic ro sc op es sanctioned 38 years of m icroscopical research. Jo b lo t’s interest in m icroscopic beings dates back to 1680,^ two years after the demonstration of the anim alcules given before the

A ca d ém ie des sciences by Christiaan Huygens (1629-1695) and N icolaas H artsoeker (1656-1725) during the sum m er o f 1678.9

^ O udem ans is cited by Van der Pas 1973, 110-111. 5 Dobell 1932, 372.

6 R oger 1993, 312-313.

^ Fournier 1991, 182-183; Van der Pas 1973, 110-111. 8 Joblot 1718 II, 2, 5.

9 Joblot 1718 II, 12-13. See Ruestow 1996, 25-26; Van der Pas 1973, 110; Cole 1926. The 30th o f July 1678, H uygens dem onstrated not only the anim alcules o f the p epper infusion, but also “a in fin ity o f sm all anim als sim ilar to the sm all frogs when they form . They w ere in s p e rm a te c a n is ' (PV AS 1675-1679, f° 185-185v). B oth observations w ere reported in H uygens 1730, 608-609. On the quarrel that follow ed, see R oger 1993, 302-304.

The observations and experiments on anim alcules, which are reported in the book, were carried out mainly betw een 1710 and

1716, as shown by m ention of the dates of the observations. The book, which was accepted in 1716 for printing by the A c a d é m i e de sculpture et de peinture, of which Joblot had been professor of m athem atics since 1699, is divided into two parts, first the construction of m icroscopes and second the study of

m icroscopical beings, mainly animalcules. The second part of the book, which I will mainly deal with here, is organised around a central them atic —the refutation of spontaneous generation with experim ents and arg u m en ts— to which m any detailed descriptions and references to the plates of the animals of infusions served as a counterpoint, being good exam ple of “m icroscopical rep o rts” . Up to but excluding Konarski (1895) and three pages by Fournier, secondary literature does not supply a com prehensive account of Jo b lo t’s book and experiments, and therefore I will analyse it in detail in the following pages before presenting its reception in the e i g h t e e n t h - c e n t u r y .

J o b lo t’s jo u rn al of experim ents guided the chronological structure of the second part of the book, in the m iddle of which the antispontaneist “hy p o th esis” is interpolated. He first reports experiments during the 1680s and 1710s on the life and death of eels of vinegar (pp. 2-1 2), followed by the animals appearing in the

pepper infusion as dem onstrated by H artsoeker when in Paris in 1678 (12-16). Joblot then describes animals from various

infusions as observed between July 1710 and Autum n 1711 (16- 39), that led to the crucial experiments on the infusion of hay carried out in October 1711 (39-40). From then on comes an interruption because Joblot stopped reporting directly to his

journal, and began synthesising previous em pirical data for the repetition of which he gave much advice (40-43). The three following pages (44-46) disclose what he calls his hypothesis or conjecture on the generation of the small animals. The next forty pages continue with many descriptions of new animals from other infusions (46-85), which brings the journal to D ecem ber 1718. Finishing with the m icroscopical reports, the book then comes to a close with a dissertation of ten pages long on optical perception through the m icroscope. The observations seem to have been interrupted betw een 1680 and 1710. But Joblot stated that he carried out his observations over 36 years (he wrote the passage in

1 7 1 6 ). Two pieces of evidence show that he indeed continued the m icroscopical observations during that time. G uillaum e Amontons, who brought him vinegar containing many eels for observation, died in 1705 and was active in the A c a d é m i e des s c i e n c e s between 1687 and 1705. Joblot also reports he made observations on the metamorphosis of a w orm in 1692 and 1693.1 1

In which way were the animals described by Joblot? He certainly did not use routine methods as in the Renaissance treatises on botany, where authors filled up several entries in a fixed order: names, m orphology, generation, costums, etc. Yet J o b lo t’s

approach rem ains category-specific, though w ithout using a rigid order adopted for the description of the animal. He is m uch more attracted by some “rem arkable ph en o m en a” p resented by an

animalcule, which leads him, on the contrary, to neglect reporting on some anim alcules considered too common. Thus no systematic

10 Joblot 1718 II, 5. 1 1 Joblot 1718 I, 34-36.

approach was used. Nevertheless, categories are m eaningful both for the inform ation displayed about anim alcules —that will

prom ote Joblot as the leading discoverer of infusoria until 1786^2- - and because these categories reveal things about the context to which he belonged. He indeed scrutinized m orphological aspects of animalcules, always trying to put the right name to the right shape —a fully diagnostics scheme— and named them as oval, sock, kidney, slug, swan, turtle, etc. Still Joblot, as Leeuwenhoek,

Huygens or, later Eichhorn or Colombo, did not use a systematical report, and paid no attention to names, despite what has been said by historians. A natom ical observations also becam e

m orphological analysis, when he identified eggs, heart and

intestine in several animals. Reasoning still plays an im portant part in his work; for instance he deduced that many of the animals should have eyes since they were able to avoid each other when s w i m m i n g . 14 Altogether, there are about one hundred experiments —m ost of these vegetable infusions— conducted over six years, that yielded betw een thirty and forty species described and engraved

{Fig. A), for which Joblot gave further details on their morphology, behaviour, and, less im portant, on their anatom o-physiology.

Death of the infusion animals and the determ ination o f their limits is a recurrent theme in the works. He noted for many animals the standard duration of their life, their m orphological changes after d e a th ly and started investigating the various causes o f death, such as putting a drop of vinegar in an infusion or in oysters, a

procedure also used to confirm the specificity o f some new kinds

12 See ch ap ter 6.4.3.

13 Stafford 1997, 233. See chapter 6. 14 Joblot 1718 II, 5, 33, 61, 70.

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F ig. A. T he dotted line tech n iq u e used by Jo b lo t to show the various m otions o f the an im alcu les. A n im al O and R: the g y ratory and straight m o tio n s dem an d an iconographie tec h n iq u e sim ila r to that used to represent the lines o f force in m ag n ets (Jo b lo t 1718, pi. 2).

of eels, appearing in the infusion of c a r n a t i o n . J o b l o t determ ined that certain animals could only live in a range of various degrees of warmth and cold.i^ Similar techniques were used previously

notably by Leeuw enhoek and Power. Attention was also paid to other dim ensions related to the “circum stances of the

observation” , like the smell of the infusions, and to more

m easurable variables such as time, motion, quantity of animalcules and temperature. Time is most likely the better heeded variable along the whole book. Joblot usually reported dates, hours and duration of the observations, life span of the various species, of the infusions, succession among time of various species in the same infusion, and the experimental time used in the procedures. He recorded for instance having boiled an infusion over a quarter of an hour. Joblot frequently kept infusions for more than one year, observing the kinds of animals that succeeded in it.19 Equally strong attention was given to types of motion of the animals,

usually well described and determined by means of idioms,

sometimes even compared to the much richer show o f d an cers. 2 0

One of the “behavioural m otions” is of course mating, which Joblot acknowledged and engraved for many species. He illustrated —with a m uch more precise technique than L eeuw enhoek used for

b a c t e r i a ^ i — through dotted lines starting from the centre of the animals (we now identify as bacteria) the various sorts of their motions {Fig. A pi. 2). He also detected the alternation o f several

16 Joblot 1718 II, 6, 18, 22, 28-29.

1^ Joblot 1718 II, 19. See also ibid. II, 15-16. 1 8 See W ilson 1995, 86; Fournier 1991, 182. 19 Joblot 1718 II, 15-16, 20.

2 0 Joblot 1718 II, 35, 50, 56.

21 D obell 1932, pi. 24 L eeuw enhoek illustrated it in a letter o f the 17th S e p tem b e r 1683.

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Fig. B. A nim al 10: the w hirlpool by w hich certain an im alcu les draw sm aller anim alcules into their m outh (Joblot 1718, pi. 6, fig. 10).

types of gyratory and straight motions in some animals he made engravings of, with an iconographie technique similar to that used to represent the lines of force in magnets {Fig. A, animal O, and R) . 2 2 A close technique of dotted circling allows the delineation of

effects of the little whirlpool by which some “aquatic caterpillars” (ro tife rs) draw smaller animalcules in their mouth {Fig. B, animal 10).23 The same methods was used later by German scholars in the second part of the century to represent the motion o f the lips in some rotifers and Ciliograda, and the m otion of animalcules {Fig.

C).24 For Joblot, such an interest in the various aspects of motion and in its representation probably arose from his professional environment, as well as from his personal interests. He indeed invented the first artificial magnet, and was a professor of geometry at the Paris Academy of Arts. Yet motion is not only referred to for the charm of its “show”—animalcules move “like dancers”— because the kind of motion also served as a mark enabling one to distinguish among two species of eels.25

Jo b lo t’s book represents a good example of the systematic rationalisation that was obtainable using the m icroscope in the beginning of the eighteenth-century. Such a rationalisation is

evident in his interest in developing five topics: 1. explaining optics

and the construction of microscopes; 2. doing research on the

microscope itself; 3. giving the measures of the focusing powers used in the observations; 4. explaining general procedures enabling one to use the microscope and to conserve animals alive; 5.

supplying readers with good narrative descriptions o f the

2 2 Joblot 1718 II, 13-14; see also ibid. II, 64-65.

2 3 Joblot 1718 II, 54-55. A is the m outh o f the anim al. 2 4 See also Fig. Z.

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Fig. C The dotted lines and the whirlpool in other animalcules (top; Gleichen 1778, pi. 23; left; Rôsel von R osenhoef 1755, 593, pi. 95, fig. 5).

observations allowing their reproduction. I leave the three first points for discussing in chapter three and develop the latter two h e r e .

On several occasions, and contrary to Leeuw enhoek, Joblot indeed showed how to use the various kinds of m icroscopes and explained the m any fine operations necessary for accurate

observations: dipping the point of a feather in the infusion to take a drop, using a pipette, handling several kinds o f tweezers, sticking the glasses of the slide with gum water, nailing insects to

cardboard, blowing sand to stick it to the glass, fitting tadpoles and small lampreys within a glass tube, setting the glass tube to the m icroscope, using a filter for the infusion, etc.^^ Each of these procedures conform s to the general scheme of showing secrets of the m icroscope developed by Joblot, which was furtherm ore

integrated to the ideology of utility and relative transparency

defended in the academic milieu of Paris, including the creation of a Société des Arts in the 1720s.27 Many tools, like the pipette, the tweezers, the glass-tubes and the “anim alcule conveyor” , are also shown in engravings {Fig. D).28 The value of these procedures is two-pronged, being on the one hand the way to make a successful observation, and on the other hand, on the level of

com m unication, they fully belonged to the social environm ent. Such a social factor appears to have been very im portant to Joblot, for he often reported having done an experim ent in collaboration with an anonymous someone, discussed with someone else or

2 6 Joblot 1718 I, 8, 74-78; ibid. II, 43, 62-63.

2 2 On utility in the A cadém ie des Sciences, see D aston & Park 1998, 353- 354, Licoppe 1996, 116-124; Briggs 1991, On Société des arts, see Hahn 1971, 109-110.

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Fig. D Joblot (1718) sh ow ed m an y tools in the engravings like tw eezers (top: pi. 3, fig. S, T, Q), g lass-tubes, and “ an im alcu le c o n v ey o r” (pi. 7, fig. PQ , pi. 10, fig. S, T, F, L).

dem onstrated the “show” of the animals to “several p erso n s” . People who saw the eels of vinegars through the microscope at the turn of the century in Paris stopped eating salad, and Joblot strove to convince them the creatures were so small as to be innocuous. As an honnê te h om m e he was delighted to “answer the difficulties [the spectator] w ould have honoured me to propose on what he was seeing [through the m ic r o s c o p e ] ” .29 O bservations were sometimes made with “a person of the higher ranking” . In other cases, some friends also made the infusions by themselves, and Joblot notified the public of their results. On several occasions, he defended a kind of moral value he imputed to the show depicted through the screen of the microscope, as being far more estimable than those showed in comedy, opera, dancing and “fights of

animals of that m agnificent City” .3 0

Joblot, however, was also pragm atic and on repeated occasions invited people to repeat experiments in order to see the

“ spectacle” and to be convinced of it by themselves. Nothing beats e m p i r ic i s m :

I feel obliged to warn that a w ritten explanation, how ever long it is, will never supply full understanding, one m ust have to m anage in using all the pieces o f this m icroscope [universal], and to prepare the objects one can observe through it. In less than tw o hours o f co n v ersatio n w ith

som eone w ell acq u ain ted w ith such an u n d e rsta n d in g , one w ill learn m ore than w hat he w ould get in eight days o f reading (...) W hich is the reason why I w ill say only necessary things as to avoid boring p e o p le .3 1

This is saying that the transmission of knowledge always has other resources than writings, this being a current b elief in Jo b lo t’s academ ic environm ent. Consistent with such a dem and for conciseness, Joblot clearly outlined the way to make infusions.

2 9 Joblot 1718 11, 62. 3 0 Joblot 1718 11, 56. 3 1 Joblot 1718 1, 59.

with cold or hot water, and unfurled before the rea d er’s eyes a whole education of seeing: how to observe, what to observe and what means could be used to refine the conditions of vision. He disclosed, for instance, suitable means for avoiding opacity of the infusions, and dem onstrated how to take advantage o f the natural conditions, such as waiting for a drop to start drying in order to slow down the motion of an animal in order to observe it b e t t e r .