louis joblot andhis microscopes · in addition, two joblot-type microscopes are in...

BACTERIOLOGICAL RzvIEws, Mar. 1976, p. 241-258Copyright 0 1976 American Society for Microbiology

Vol. 40, No. 1Printed in U.SA.

Louis Joblot and His MicroscopesHUBERT LECHEVALIER

Waksman Institute ofMicrobiology, Rutgers University, The State University ofNew Jersey, New Brunswick,New Jersey 08903

INTRODUCTION .................. 241JOBLOT'S BOOK .................. 242

Selections from Part I .................. 243Selections from Part II .................. 248

CONCLUSION..................... 256LITERATURE CITED .................. 258

INTRODUCTION

Louis Joblot was born in 1645 in Bar-le-Duc,a small town located where Lorraine andChampagne meet in the picturesque valley ofOrnain. He died in Paris in 1723. During hislife, Joblot was engaged primarily in the studyof physics: magnetism and optics had a specialfascination for him. It is mainly because of hismicroscopes and what he saw with them thatwe remember him.

Louis Joblot was a contemporary of Antonyvan Leeuwenhoek, both men dying in the sameyear. The details of the life of Joblot have beenpoorly documented, and what little we knowwas religiously assembled by a certain Wlodi-mir Konarski who buried his work in an ob-scure journal, published in 1895, dedicated tothe local history of Joblot's native town, Bar-le-Duc (12).Louis Joblot was baptized on August 9, 1645.

His parents were probably local merchants ofsome wealth. How and when he found his wayto Paris is not known, but in 1680, he wasappointed assistant to the well-known engraverSebastien Le Clerc (1637-1714) to teach geome-try to the students of the Royal Academy ofPainting and Sculpture. This position carriedno salary, and we must assume that Joblot waseither independently wealthy or had someother source of income, possibly from givingprivate lessons in mathematics. In 1697, herequested a leave of absence of 15 to 18 monthsto travel in Italy, the cradle ofthe arts. In 1699,he was appointed Professor of Perspective andGeometry, replacing Le Clerc. In his lectures,he stressed the mechanism of vision and evenindulged in the dissection of eyes. He was thenentitled to a salary of 300 pounds a year, whichwas less than that paid by the Academy to amodel!

In 1717, it was his turn to request the ap-pointment of an assistant, and four years laterhe retired, retaining the title of Counselor andProfessor Emeritus. He died on April 27, 1723.

This is the extent of the hard facts that wehave concerning the life of Joblot. To this wemight add that he was probably not married,that he associated with those interested in sci-ence, delighting them with experiments anddemonstrations in the field of magnetism andmicroscopy, and that he lived in that part ofParis where makers of precision instrumentswere concentrated.

Joblot interests us because of a book that hepublished in 1718, which was entitled Descrip-tions and Uses of Several New Microscopes,Both Simple and Compound (Descriptions etUsages de Plusieurs Nouveaux Microscopestant Simples que Composez). Part of it wastranslated into English by Adams in 1746 (1).Joblot's book was republished in 1754 and 1755in two volumes entitled Natural History Obser-vations Made with the Microscope (Observa-tions d'Histoire Naturelle Faites avec le Micro-scope). The publisher, Briasson, had bought theplates of Joblot's book and had added somematerial of little importance, mainly on in-sects, to the original text in order to make a"new book." For obvious reasons, the secondedition of Joblot's book never received the au-thor's blessing and was simply a device to makemoney for M. Briasson.Jean Senebier (14) of Geneva refers to Job-

lot's book in the introduction to his 1787 Frenchtranslation of Spallanzani's Opuscoli di FisicaAnimale e Vegetabile. After that, Dujardin(1841) (9) wrote: "Joblot, in 1754, published mi-croscopic observations which were rather goodfor the time, and which are not without value,in spite of the ridiculous names used...."Dujardin did not seem to be aware of the fact

that the 1754 edition was only, as far as micro-biology is concerned, a reproduction of the 1718edition. If Joblot's observations were good for1754, they must have been outstanding for 1718!Dujardin's error was pointed out by Fleck in1876 (10).

In 1894, Cazeneuve (5) explained how he hadread the 1754 French translation of Henry

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Baker's book on the microscope originally pub-lished in 1743, and how he had been impressedby Baker's ideas on spontaneous generation.He noted that Baker referred to Joblot severaltimes. Subsequently Cazeneuve was able to gethold of the second edition of Joblot's book, fromwhich he quoted key passages. From then on,the scientific world was to be aware of Joblot'simportant contributions.Boyer (1894) (4), who had the good fortune of

owning a copy of the original Descriptions ofJoblot, published some additions and correc-tions to Cazeneuve's comments. One year later,Konarski (12) published his comprehensivestudy on Joblot. In 1923, Dobell (7) comparedthe protozoological contributions of the two pi-oneers who had passed away two centuries pre-viously: Leeuwenhoek and Joblot. A few pagesof Joblot's book were reprinted by Woodruff in1937 (16).Since the original edition of Joblot's book and

Adams' translation of selected passages are rar-ities that few persons will ever have the chanceto see, I have included a sampling of Joblot'sillustrations, together with enough of his textin translation, to give the flavor of the book. Inmaking a fresh translation of Joblot's text, Ihave taken care to follow the spirit and style ofthe French of his time.To appreciate the importance of Joblot's

book, it is enough to remember that it is thefirst separate treatise on microorganisms, onein which some protozoa are illustated for thefirst time, and that it contains the first experi-ments ever made to disprove spontaneous gen-eration ofmicroorganisms by heat sterilization.To this, I could add that this book probablycontains the first reference to the use of a shak-ing machine in a microbiological process.

JOBLOT'S BOOKDescriptions and uses ofseveral new microscopesboth single and compound with new observa-tions made on an innumerable multitude of in-sects and other animals of various species,which are born in natural and prepared liquors.By L. Joblot, Royal Professor of Mathematics atthe Royal Academy of Painting and Sculpture,living on the Quay ofthe Clock of the Palace, atthe large Grape.'

in ParisAt Jacques Collombat, Printer ordinary of theKing, and of the Royal Academy of Paintingand Sculpture, Saint Jacques Street at the Peli-can'

' Houses, at that time in Paris, often had signs used torefer to them as we now use numbers.

MDCC XVIII

With the consent and authorization of the King

PREFACEOne part of this work is no more, so to speak,

than a sort of a Journal of the observations thatI have made on an infinite multitude of verysmall animals which are beyond the ordinaryrange of our vision.The ease of utilization ofmy new microscopes

has imperceptibly led me farther than I hadplanned and forced me into details that mightappear dull to those who are not accustomed tofollowing nature in its workings....

I have added to my observations conjectureson the production of various species of smallanimals which are found in liquors. I cannotshare the opinion ofthose who attribute them toputrefaction; this idea is hard to accept since itwould mean abandoning to the irregularity ofchance Works which are always accomplishedwith an order that one cannot cease to admire. Ihave thus substituted another concept whichseems to fit clearly with the almost infinitemultitude of all my experiments.

I have divided this work into two parts: thefirst contains the construction and uses of sev-eral Microscopes which are most convenient andmore perfect than any of those that have so farcome to my attention. One can see them inperspective on twenty-two plates,' with theplans and profiles necessary for good under-standing of their mechanisms and use. Thereare two or three of these microscopes whichhave almost universal application...On suchan instrument one will be able to mount easilyand rapidly, not only lenses of various foci, butalso very small microscopes with two and threelenses which are from one to three inches long,the shorter ones having considerable advan-tages, such as letting one observe objects intheir natural, upright position....And to ... a ... universal microscope one will

be able, very easily and without difficulty, toapply fishes of various species such as tadpoles,frog, lampreys, eels, ... minnows etc.' in thetail ofwhich, and other places, one will have thepleasure of seeing the various movements ofblood in variously curved vessels...

... I have furnished several Microscopes torenowned Physicians, famous Anatomists, andto several other illustrious amateurs in thesenovelties, and it is almost impossible that eachone of them, while pleasantly occupied with theexamination of the surprising effects of nature,will not discover every day new and singularthings, which they will be able to communicateto the Public both by the means of private

' Three of these are reproduced here.' These animals were held in a tube in such a way that

their tail was brought in focus of the lens.

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LOUIS JOBLOT'S MICROSCOPES 243

lectures and by publication in the "Journauxdes Scavans"....The second Part of this Book contains twelve

Plates' ... by means of which are illustrated aportion of the new discoveries that we havemade....

I have been able to describe the small ani-mals which are found in the infusions discussedin the second Part, only by giving them differ-entiating names. To this end I have looked forthings in nature which are rather well knownand which would have some resemblance to thefishes that I have seen in my liquors... Limitedby my lack ofknowledge ofthe various beings ofnature, I have been forced to name other fishesdifferently, by giving them names which, insome way, marked their particular inclinations,or their most common movements. Thus, I havenamed some Bagpipes, Ovals, Aquatic caterpil-lars, Funnels, Crested hens, Kidneys, etc. Toothers I have given the names of Blind ones,Somersaulters, Gobblers, Fickles, Buffoons, El-egants, etc....

From this introduction, in which the authorstates that he has borne the cost of the publica-tion of the book, it is quite obvious that Joblot,a professor, unlike Leeuwenhoek, an amateur(7), was most interested in sharing his workwith others, not only his results, but also hismethods.

Selections from Part IThis first part of Joblot's book, appropriately

entitled: "Description of the microscopes that Ihave used," starts with the apology that beforehe could relate his observations:

... It was necessary to describe all the parts ofthe instruments that I have used in these inves-tigations. Those who have a taste for these dis-coveries will be able to verify my experimentsby themselves and will be able to push themfarther than I have done.

The technical description of the microscopesis prefaced with the warning that:

Each microscope seems to me to have proper-ties that make it suitable only for certain uses.Thus, I do not think that one could invent onewhich would have all the properties of thosethat I shall propose....

The microscopes described by Louis Joblotrange from simple magnifying glasses var-iously mounted (Fig. 1) to compound micro-scopes with four lenses (Fig. 2).

Joblot distinguishes those microscopes thatwere especially made for the observation of liq-uors from those made to observe specimens held

' Four of these are reproduced here.

at the end of pins or clamps. Another type is acylindrical glass chamber within which smallanimals can be observed for prolonged periodsoftime (Fig. 3). These are called "graves," sinceanimals often died there during the period ofobservation. Finally, the "universal micro-scopes" are those with attachments permittingthe observation of "all sorts of small objects;hard, soft and all that can be seen in liquids."The descriptions of Joblot's microscopes are

very detailed as far as the mechanical parts areconcerned, but no details are given on how thelenses were made; the only references made tothe optical properties of the lenses are theirfocal lengths. In one case, the lens is referred toas having been blown (i.e., of blown glass); byimplication, this would indicate that all theother lenses were ground. At one point, the useof a lathe in polishing or cutting lenses is men-tioned.Not many microscopes exist of the types Job-

lot designed, and it is entirely possible that notone of the original microscopes that he ownedhas survived.The Royal Microscopical Society has an ex-

ample of one of the microscopes designed byJoblot (2). It is inscribed, "J. Langlois, Eleve duSieur Butterfield, aux Armes d'Angleterre, aParis" and is also described and illustrated byClay and Court (6). It is a universal microscope.Another less ornate Joblot-type microscope,also illustrated by Clay and Court, is now atthe Museum of the History of Science in Ox-ford. In addition, two Joblot-type microscopesare in the Nachet Colection in Paris.On pages 6 and 53 of Part I, Joblot notes that

some of his microscopes, at least, were built by"Monsieur Le Febvre, an engineer [who was]very skillful in the construction of mathemati-cal instruments."

In Joblot's book, details are also given on theuse of the microscopes, the placement of thespecimen, and the types of subjects recom-mended for observation. Blood circulation wasone of his favorites: in more than one place hegives instructions for the observation of capil-lary circulation. The use of slides, depressionslides, and cover slips is also discussed.As can be seen in Fig. 2, diaphragms were

used extensively. It is entirely possible thatthey may have been an original invention ofJoblot's, and they certainly improved the qual-ity of the images that he saw. On the basis ofthe focal distances given by Joblot, Konarski(12) concluded that his most powerful micro-scopes may have been capable of magnifyingsome 400x, essentially double the power ofLeeuwenhoek's instruments.

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Oee-ewdvat hed2ort&om&. -P-3

FIG. 1. Translation: "Drawing of a magnifying glass-carrier."

I.Among the simple things that one could ob-

serve, grains of sand, on which vinegar eels(Nematodes) could be placed, were recom-mended.

... But if on these same grains of sands youlet fall a small drop of vinegar in which thereare eels, they will furnish you with a new amus-ing spectacle, because of the straits in whichthey find themselves as they try to get free ofthe masses ofrocks formed by the grains of sandfalling on their bodies and by the shaking theeels give the grains of sand as they push themapart, to make a free passage.

Concerning flies:

one can easily examine all their exteriorparts and thus discover the error of ancient

Philosophers, and even of a few modern ones,who think that flies cling to bodies on whichthey walk only because a kind of sticky humoroozes continuously from their feet....

Glass cylinder microscopes, which some per-sons refer to as tombs or cemeteries of variousanimals [Fig. 3] . .. are very useful to observe apart ofwhat is going on, both in living and deadanimals ranging in size from that of a flea tothat of a June beetle. ...

... One usually despises insects and othersmall animals which men believe owe theirbirth to decaying matter; but it is easy to showthat this scorn is unfair and that it is based onlyon ignorance.... The smallest gnats are as per-fect as the largest animals: the proportions oftheir members are as good as those of others;and it even seems that God has wanted to givethem more ornaments than he gave to the

i I1

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MICROSCOPES 245

FIG. 2. Design of one of Joblotes compound microscopes.

larger animals so as to compensate in this man-ner for the smallness of their bodies.They have crowns, crests and other accouter-

ments on their heads that surpass all that theextravagance of women can devise....

If one encloses certain caterpillars in a glasscylinder microscope and if one examines themfrom time to time, one first sees them all cov-ered with long shiny hairs of various colorsdispersed with such artistry that whichfrightened us at first becomes a subject of admi-ration, since after about five to six weeks theyabandon their charming coveralls ... to be seenin shape of several cocoons somewhat similar tothose of silkworms without any sign of motionwithin. After a period of time, our surprise dou-bles as we witness the exit of butterflies well-winged and all alive....

If you enclose in this microscope a big spiderwith an ordinary fly, also rather big, you willhave the pleasure of seeing the fly in a greatstate of agitation while the spider will remainmotionless, lying on its back, its legs up in theair and spread apart; waiting with great calmuntil the fly, tired of flying here and there fallson its body. Then the spider will surround thefly with its legs, prick it at the throat, and kill itsuddenly. It will be satisfied by drinking itsblood without eating the rest of its body; thisremains whole for a long time until other verysmall white insects come and partly devour it.

Describing the types of observations that onecan make with lenses held by the elegant artic-ulated arm illustrated in Fig. 1, Joblot re-

marked:

yr-a'

B A4 ~~~~~~4

k -*A *< 'i,i

I-his X

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LOUIS JOBLOT'SVOL. 40, 1976

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246 LECHEVALIER

G

Fi,d.:n. G(.-)

B

A

E _

C

FIG. 3. Cylindrical glass chamber, under which animals can be observed for long periods of time.

.. . One has discovered seeds in severalplants, which one was convinced without reason

had none, including ferns, mosses and truffles,etc.One has observed that blood is composed of a

white and transparent watery fluid in whichswim red globules of various sizes. One has seenit circulating in the vessels of several livinganimals....

The statement that truffles have "seeds" is ofinterest since Micheli's Nova Plantrum Gen-era, in which he demonstrated that fungi pro-duced "seeds" capable of reproducing their like,was to be published only in 1729. Althoughsome contemporary French botanists such asTournefort and de Jussieu were of the opinion

that fungi had "seeds," many learned personsstill thought that fungi were the result of thetransformation of the juices of dead plants andanimals (13).Joblot gave the following information about

the optics ofone ofhis compound microscopes (1old Paris ligne = 2.175 mm):

The ocular, which is a glass convex on bothsides, has a focus of eight lignes; it has beenplaced about six lignes below the eye.The glass in the middle, which is also convex

on both sides, has eighteen lignes of focus; it istwelve lignes from the ocular.And the lens, which is of four to five lignes of

focus, is placed at least thirty lignes from themiddle glass; and this same lens may be placed

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N O U V E L L E S

OB S E RVAT ION SiFaites avec de nouveaux Microfcopcs, fur unc multi-

tude innombrable d'infekes, & d'autres animauxde diverfes efpeces, qui naiffenit dans des liqueurspre'pare'es, & dans celles qui ne le font point.

SECONDE PARTIES

FIG. 4. Frontispiece of the second part of Joblot's book. It is believed to show Joblot in his laboratory.

... even further if one wants the object to ap-pear larger ... but, one should be warned thatthe object will not appear so well lit. ...

After having described the microscope illus-trated in Fig. 2, and having explained how itcould be transformed into a telescope, Joblotdescribed a universal microscope, equippedwith more than one objective. He then proceedsto explain how to prepare the objects for obser-vation. Cautiously he warns:

Before I start, I am forced to warn [thereader] that a written explanation, no matterhow long, will not give all the information nec-essary for the proper manipulation of all theparts of this Microscope or the preparation ofthe objects that one wants to observe; and thatin less than two hours of conversation with aknowledgeable person, one will learn morethings than one would during eight days of bor-ing reading....

To the microbiologist, the most important isJoblot's method of mounting liquid samples:

If one now wishes to observe what one candiscover in a liquor, one only has to dip the

small end of a writing pen into an infusion ofsome plant, to wet the center of the glass slidewhich is placed . . . in front of the appropriatelens which is focused. Thus, one will see, invarious liquors, animals that swim, others thatcrawl and swim and finally others that walkand swim.One should note that in order to see many

eels, it will be necessary to use a concave glassslide in which a rather large drop of vinegar hasbeen deposited....

Without mentioning Malpighi, Joblot pre-sents a "new invention" that enables one to seethe circulation of blood in the tail of a smalltadpole. He explains:

One of the finest discoveries that has beenmade in medicine is that of the circulation ofblood, which is attributed to Herv~e [Harvey], afamous English Physician who published it in1628, or rather to Father Frapaulo, a famouswriter of his time.No matter how sound the reasoning and the

experiments used by these two learned men toarrive at this opinion, all the old doctors of thetime opposed this novel idea and did all theycould to fight it because, at the time, Harvey

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248 LECHEVALIER

and Frapaulo lacked the possibility of perform-ing experiments to prove such a fine discovery.

After describing how to handle small fish inorder to observe the circulation of their blood,Joblot ends the description of his 16 microscopesand concludes Part I.

Selections from Part IINew Observations, made with Microscopes,

on an innumerable multitude of insects,' andother animals of various species, which are bornin natural and prepared liquors.

Second PartPreface

After having explained in the first part ofthisWork the construction and uses of several newMicroscopes made to observe liquids which aremore perfect and easier to employ than any ofthose which have come to my attention, up tonow; it is necessary to put them to use in orderto study the anatomical History of an almostinfinite multitude ofvery small animals, aerial,terrestrial and aquatic, which have been so farunknown, due to their smallness and the greatdefects which are characteristic of ordinary Mi-croscopes.

First ChapterOn Eels, Snakes, or small worms that one finds

in vinegarIt has been known that in summer vinegar

contains many small eels, but only since theinvention of the Microscope has it been knownthat these snakes have a very pointed tail. Thishas led several persons to believe that vinegarhad a prickly taste only because of the impres-sion that these small animals made on thetongue. But the various experiments that wehave made on this subject have convinced usthat the acidity which is noted in this liquor wasnot due to these animals but only to its invisibleparts, since we have seen good vinegar withouteels.At the beginning of the month of April of the

year 1680, we did not see any of these insects invinegar which had been exposed to the Sun for afew hours.

In Paris, towards the end of the month ofJune of the same year, and all the rest of thesummer, it was difficult to find vinegar inwhich there were no eels. Thus many peoplewho had seen them with our Microscopesstopped eating salad. I told them that the eelswere about a hundred thousand times smallerthan they appeared with these instruments;that the heat of the stomach killed them in aninstant; and that since they had up to theneaten salad without having been troubled, they' Joblot uses the terms "insects" and "fishes" to designate

almost anything!

could continue to use this thing that was agree-able to them without danger. And although allthese reasons seem to them sound enough andconvincing enough to lead them out of the errorinto which they had fallen, most of them couldnot understand why snakes which had seemedto them larger than the finger and longer thanthe arm would not produce a bad effect on theinterior membranes of the stomach.

This led Joblot to develop a method of riddingthe vinegar of the worms. He concluded thatmild heating followed by filtration of the vine-gar through paper permitted one to obtain "theliquor as one would want it."

Those who believe that all generations arisefrom eggs say that at the beginning ofthe warmseason certain small animals which are imper-ceptible to our eyes, which fly or swim in air,acting as though attracted by the spirituousparts which are continuously exhaled by thevinegar, let drop eggs into this liquor, where,receiving a moderate heat which is caused by amild fermentation, they can hatch and thusfurnish in a short time the small animals that Ihave discussed.

This manner of the birth of eels in vinegar isnot in accord with what two of my friends haveobserved ... and with what I have seen in twosimilar experiments that I shall discuss at theend of this second Part, where I report on theobservations that I made on two small eelswhich were moving back and forth in the bodyof their mothers....No matter how much attention I gave to the

observation of the head of these eels in order todiscover their eyes, I have never succeeded,either because of their smallness or because theliquor, thickening as it dried, covered them,forming a veil through which they cannot beseen. I am, however, very sure that they havethem since the detours that one sees them maketo avoid one another do not permit one to doubtit for a moment....

In good vinegar, it is very rare to see otheranimals mixed with the eels, but they can befound rather often in spoiled vinegars....

Chapter II

On common vinegarVinegar makers make such a great mystery

of how to make vinegar that they teach it totheir apprentices only after seven years. Possi-bly, one might be surprised that they act in sucha way when one learns how few precautions onehas to take in order to make good vinegar. It isenough to scald a new barrel with ordinaryboiling water and to replace it as soon as possi-ble with the best wine that one can obtain alongwith a little salt....One should point out that vinegar improves

more readily and is made more rapidly when

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the vessel is in a warm place and is open thanwhen it is closed and in a cold location....

Monsieur Hombert, I of the Royal Academy ofSciences, has proposed a new way of makingvinegar from good wine, one which is the fastestof all known until now. It consists in tying abottle about two thirds full ofwine to the click ofa mill. The frequent jolts that the liquor re-ceives so break its principles and whatevermade it mild, that in a few hours it becomes avery strong vinegar which can be kept for a longtime in the same state.

After stating that the addition of herbs andother seasonings to vinegar to make "compoundvinegars" did not prevent the growth of vinegareels (Chapter III), Joblot launches into the de-scription of further observations of these littlebeasts (Chapter IV). In so doing, he introducedthe use of the cover slip.

[On] the 25th of September 1710, around nineo'clock at night, I placed a small drop of vinegarwhich contained eels in a concave depression ofglass which is used to carry the object, and I gotthe idea ofcovering the top ofthe concavity witha small piece of glass, flat on both sides, in orderto prevent the rapid evaporation of the vinegar.This was perfectly successful....

Chapter VObservations made on several kinds of infusionsofpepper grains, placed in ordinary cold waterAt least 38 years ago, Mr. Hartsoekerl

brought a new Microscope from Holland toFrance, which was especially made for the ex-amination of liquids and equipped with a singleblown lens; with it he showed us that ifyou soakgrains of black pepper in ordinary cold water,after a few days one could see numerous smallanimals. This permitted us to observe manystrange things that we had not yet seen.

First, with the help ofthis glass lens, one sawanimals of a light golden color, about of the sizeand shape represented in plate 2 [Fig. 5] at thepoints marked B, D, K, H, 0, R, L. Their bodieshad small areas more transparent than the rest.

20. The regular oval shape that these animalsusually have and their rapid motion, do notpermit one to ascertain at first glance whichpart oftheir body harbors their head, but with alittle patience one soon determines this by thedirection in which they continue to move. Also,the liquid in which they swim thickens imper-

1 Possibly Wilhelm Homberg (1652-1715), first physicianto the Duke of Orleans. Mainly known as a chemist, hisquantitative experiments on acids and bases are the firstdemonstration of equivalent weights.

I Nicolas Hartsoeker (1656-1725), a Dutch optician andnaturalist who lived in France and in Germany. He wasauthor of Eclaircissements sur les Conjectures Physiques(Amsterdam, 1710) and a Cours de Physique, which waspublished after his death (1730).


ceptibly due to the evaporation of its most sub-tile and most agitated components, resulting ina gradual diminution of the speed of thesefishes, and it is then that one can leisurelyobserve several things which give one the occa-sion of admiring the wisdom ofthe Creator evenin the tiniest parts of these small creatures....

3°. One observes that two ofthe animals fromthis infusion advance directly, one from A to Band the other from C to D, the first returningalong the dotted line BE, and, the second fromD to F.

4°. I have sometimes observed that two ofthese fishes, after one would have moved alongthe line GH and the other the line IK, leavebetween them a space too small to be traversedby a third marked L. The latter, caught andsqueezed between them, elongates while bend-ing to escape toward M.

5°. There are some which after having fol-lowed a straight line such as NO, turn so rap-idly around point 0 where their head is, thattheir oval shape appears to become circular;after that they rush toward P with great speed.One can also observe others, which after havingfollowed a straight course, similar to QR, turnaround their center of gravity marked R, thustracing a large number of concentric circles,then dashing along with extraordinary speedcan be seen following another straight linemarked ST. This was what we noted in the firstinfusion in which there were only Ovals, as Icall these fishes; and here is what we saw in asecond one observed with hand-polished lensescut on a lathe, which is the way to make themmore perfect than the previous ones.The first figure represents a fish, which I call

the Crested Hen, whose head is ornamentedwith hair rather than feathers; its most commonmotion was circular. This fish was the only onethat I have seen in this infusion and I havenever seen a similar one in any other that Iprepared.The second species offish, illustrated at 2, are

animals that I call silvered Bagpipes and aboutwhich I shall speak again in the continuation ofthis Account.The third is a large aquatic spider whose

mouth opens wide enough to swallow the pre-ceding bagpipes.The fourth figure represents two of these spi-

ders coupled which are turning together ontheir common center of gravity.The fifth figure represents two ofthem which

are also coupled but which are swimming in astraight line. We will describe these largeaquatic spiders more exactly toward the end ofthis second part when we will discuss animalsthat we have seen in an infusion of a smallamount of wood of an acorn-bearing oak.The sixth figure represents another fish, the

body of which is about the shape of a Weaver'sbobbin. It has long hairs on its behind which ituses as fins.

Finally, under the spot marked seven, are

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250 LECHEVALIER

C9e, (awcoz~ amce ifrm

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dul'o e- Pt. 2.

o, cjt (

0 F .

F..-Tastin O w i h ab k

FIG. 5. Translation: "On water in which pepper has been soaked."

illustrated a multitude of small insects of var-ious shapes and sizes which were just born andwhich are usually used by the larger ones forfood.

After having discussed the comparativevalue of using "white pepper" and "long pepper"in making infusions that will contain interest-ing "fishes" including some "aquatic caterpil-lars" and some "eels" thicker and shorter thanthose found in vinegar, Joblot made the obser-vation that cold is not likely to kill microbes:

... We complete this Chapter with a warningthat these fishes tolerate the rigors of a veryhard and very long winter and that they remainalive under a sheet of ice some two lignes inthickness. As the ice gets thicker, the fishes go

deeper within the vessel. But ifyou melt this iceand keep this infusion, you will see these fishesafter about 15 days of milder weather and inmuch larger numbers than they were beforethis water was frozen.

Chapter VIObservations made during a whole year ofwhat

was found in a cold infusion of senna... All the animals seen in that infusion

[senna], except worms, died as soon as I woulddip the end of a pen dipped in vinegar into thedrop of the infusion but this infusion of sennadid not have the same effect on the eels of vin-egar that vinegar had on those of this infu-sion....

... [then] I got the idea of dipping a smallcapillary tube into the infusion, having previ-

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ously taken the precaution of blocking the up-per end [of the tube] with my thumb which Ithen removed when the tip was at the bottom ofthe vessel. After having blocked the upper endagain I put much more of this infusion thanusual on the specimen holder. ... However, Isaw only four or five animals in this big drop,whereas if I had taken as much from the sameinfusion at the top of the vessel I would havefound perhaps one hundred times more.

In winter, tepid water does not kill these fisheswhich we are discussing; on the contrary, theyseem to move much more freely there than be-fore but when it is a little warmer they all die.Thus there is a certain level of warmth whichenables them to live and another one, slightlyhigher, which kills them.On the 30th of January 1711, I observed an-

other kind of fish which appeared in ratherlarge numbers in this infusion of senna andwhose swimming seemed odd to me since duringits forward motion it was rocking to the rightand to the left as a small boat would do if, whilerunning with a current, a man standing up inthe middle of it would lean on one side and thenon the other and in so doing, would rock theboat as a form of amusement.

I added ordinary water for the sixteenth time,in order to increase the volume [of the infusion]and to decrease its thickening, and also to fur-nish the animals which were there some newsubstances at the same time.

I saw the next day that these animals weremoving much faster than previously and with-out rocking, from which it seems to me, onecould conclude that they were able to cleave thisliquid more easily....At last, the extreme heat which occurred to-

ward the end of the month of July 1711 andwhich lasted three or four days, killed almostall the animals of this infusion which had ex-isted for one full year....

Chapter VII is a description of what Joblotsaw in the fluid from six oysters. He was im-pressed by the presence of only one type of littleanimal, which he called "little oysters," and bytheir sensitivity to vinegar since "the very odorof vinegar is a poison for them."

After describing what he saw in various infu-sions, Joblot comes to a discussion of the originof the "insects and fishes."

Chapter XVSecond infusion of fresh hay

On the 4th of October 1711, I placed a littlefresh hay in ordinary cold water in two differentvessels. One I stoppered the best I could withwell-wetted fine parchment and the other I leftopen. Two days later, I observed three types ofanimals which were present in rather highnumbers in both infusions. This experimentseems very appropriate to convince one that

these animals were produced from eggs thatother animals had deposited on the hay and notfrom those which were dispersed in air....

Third experiment made on similar hayOn the 13th of October, I boiled similar fresh

hay in ordinary water for more than a quarter ofan hour. I then placed an equal quantity in twovessels of about the same size. I sealed one rightaway even before it has cooled down: in theother one which I had left open I saw animals atthe end of a few days but not in the infusionwhich had been sealed. I kept it sealed a consid-erable amount of time in order to find someliving insect, if any should grow, but findingnone, I left it open and after a few days I observedsome. From this, one should understand thatthese animals were born from the eggs distrib-uted in the air since those which would havebeen encountered on the hay had been com-pletely ruined by boiling water.

Chapter XVIIIHypothesis to try to explain the birth, the growthand the death of animals that one observes inprepared liquors and in those which are notIn the past one used to believe that all insects

and other small animals were engendered byputrefaction but, since several famous Philoso-phers have revealed the observations on thissubject that they have made with much careand exactitude, one has been cured of this error.They have proved by a number of experimentsand by unimpeachable reasoning that all ani-mals, no matter what their nature may be,come from eggs. Indeed, how could one imaginethat the alteration and putrefaction which comefrom the division and the separation of parts ofa body into other smaller parts could in turnlead to their arrangement side by side so thatthey could unite as need be to form living beingswhich are capable of searching for what is nec-essary to feed themselves by walking, crawlingor swimming and even to produce their ownkind as one can see is done by those animalsthat one sees in plant infusion? I do not believethat a man capable ofthought could imagine sucha thing no matter how much effort he wouldmake in this direction.But in order to have that which is needed to

combat this presumption which is so dangerousto religion by attributing to chance, that is tosay to a cause which is neither apparent nornecessary, that which is assuredly the most per-fect work of an infinite power, one has only toheed the experiments contained in this accountand the observations that follow.

Decay is not the cause of the generation of thelittle animals that one sees with the microscopein the water of mussels and in that of scaledoysters since one sees them before these watersbecome corrupted.

It is not even the cause of the generation ofan

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infinity of small fishes that we have seen invarious infusions since the matter of all theseinfusions was not yet altered and corruptedwhen one started to see them.

If rottenness was the cause of the birth of theinsects which we see in a single infusion, oneshould see them all (at the same time) as soon asthe infused matter would have decayed. Thisdoes not happen since one sees them succeedingeach other during a period of thirteen to four-teen months.

If rottenness contributed to the generation ofthe insects that we are discussing, the morerotten a substance, the more animals oneshould see in it. However, one observes theinverse in urine which one keeps severaldays....One may add that there are substances which

change little or not at all in odor, which furnishanimals different from each other during all thetime that one keeps them in infusion.

Here it seems to me are experiments in suffi-cient quantity to show that neither alterationnor corruption nor bad odor are the causes ofthegeneration of animals whatever they may be.Let us then try to establish a hypothesis toexplain those most surprising things that maybe seen in the infusions of plants. I would pro-pose that in the air close to the earth there fliesor swims an innumerable number of small ani-mals of various species, which while fasteningthemselves to the plants of their choice to rest ornourish themselves, deliver their little ones ordeposit their eggs there.And that these same animals also drop young

and eggs into the air through which they travelespecially in places where they are attracted bythe volatile corpuscules which continuously es-cape from plants and generally from all otherbodies whose parts have some motion whichrenders them volatile.

Furthermore, it is appropriate to remark thata given plant can be the favorite of certainspecies of animal and thus becomes the reposi-tory of its eggs....

Joblot was not only interested in observinglittle animals; he was also concerned with theirorigins and their ecology. He noted in Chapter20 that an infusion made from rhubarb was oneof the items that remained free of animalculesthe longest. At the most, only a few individualsmight be seen and these only after a long periodof incubation. On the other hand, in the nextchapter, we learn that an infusion of a largemushroom was especially fertile, eventually at-tracting small flies that deposited their littleworms in large numbers.At the end of Chapter 24, Joblot introduced

the concept of selective toxicity and recognizedthe antimicrobial effect of certain metals.

Important remarksIf one prepares an infusion of hay, for example,in a vessel where there had previously been aninfusion of a plant or ofaromatic drugs strong inodor, and if this vessel had not been cleanedcarefully after this first infusion, the secondmay not be successful.As a matter of fact, the water that one ob-

tains from a poorly tinned copper fountain is notsuitable to support the life of most of the ani-mals of our infusions because this water ac-quires during its stay in this vessel a peculiarquality that poisons them. In the past, I haveeven heard from Monsieur l'AbbW Bourdelot,Physician of his Highness the Prince of Cond6,that drinking water which had been kept inpoorly tinned fountains, caused runs of the ab-domen.

Looking at an infusion of old hay, Joblet gavethis description of rotifers:

... Some of these animals are the most surpris-ing and the most extraordinary that I have seenin plant infusions and this is as much due totheir size as to their behavior. I have illustratedtwo of them in 10, 10 (Plate 6) [our Fig. 6]. Abeing the head, B the tail which is forked, C theheart which one can see moving regularly and Dthe intestine of these animals which I shall callaquatic caterpillars....

Their way of moving consists of pressingtheir point B on the slide of the microscope andstretching as much as they can then pressingtheir anterior extremity on another place, theybring up their behind and thus move by creep-ing....When these caterpillars stop, one ordinarily

sees that they display a large mouth, marked Ain the largest of the two, the lips of which arefurnished with hairs which appear black andwhich move with such great speed that one seeswith amazement that the small fishes and otherbodies which are about an apparent inch awayfrom the mouth seem to rush into it.

Joblot thus expresses his admiration and hisenthusiasm for the spectacles of microscopy.

Finally we have observed in mixtures of infu-sions of hay and celery. a very diverting spec-tacle since in the smallest drop the spectatorcan discover in an instant a dozen fishes differ-ing from each other and so strange to see andobserve that I do not think that the entertain-ment of Comedy, of the Opera with all its mag-nificence, of rope dancers, acrobats or the ani-mal fights that we can see in this superb City,could be preferred to it.

It is in an infusion of celery that Joblot de-scribed some "fishes" that he called "the blindones." His description and illustrations (Fig. 7)

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FIG. 6. Translation: "This plate contains what was most remarkable in nine sorts of infusions."

leave little doubt that he was referring to someVorticella.

The fishes that I call Blind Ones (Plate 8; 7)often open their large mouths and then one seesthat all the little bodies, which are apparentlyonly one inch away, seem to precipitate them-selves towards this spot, then move aside as ifthis animal were pushing them speedily back.One also notes that in some of these last

fishes, a part of their tail is twisted like a cork-screw.

Joblot's nomenclature is always a delight:witness, Plate 8, Fig. 2 (our Fig. 7), the pooranimal which he baptized "Urinal," while call-ing those clustering around number 3 "Silvered

Kidneys." In his "Swans" illustrated at 8, 8, 8one is inclined to recognize members of thegenus Dileptus or Amphileptus. Conceivably,the "Aquatic Spiders" or "Gluttons," illustratedin 9, might well have been species of Stylony-chia. In another plate is illustrated a number ofrotifers that Joblot had found particularly en-tertaining because of their ability to "somer-sault with great dexterity." He called then"Aquatic Crowned and Bearded Pomegran-ates."Further on we find a summary of Joblot's

knowledge of microbial ecology.

... I should warn [the reader] that air con-tains during one season that which it does not

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FIGI 7 Tansaton 7nusonof trw nd piesof het.

FIG. 7. Translation: "Infusion of straw and spikes of wheat."

contain during another and that animals whichare abundant in one place during a whole yearare often different from those that can be seenduring another. These differences offer agreea-ble pastimes for persons who take the trouble ofcontinuing their observations and who makethem in different places at a considerable dis-tance from each other. . one should not be sur-prised if one does not always discover the samethings that I am discussing, but instead finds,in similar infusions, things that I have not men-tioned because the new insects that one will seewould have escaped me or because during theseason during which I performed this experi-ment there were none of that species.

While discussing the animals seen in an infu-sion of oak bark, Joblot made the followingcomment concerning his technique;

These observations were made with the lightof a candle and the visualization of the objectswas better than when made with daylight be-cause since one could lean on a table, the micro-scope was held more firmly and in addition onereceived less stray light than when the samethings were observed in daylight.

Further on, again in an infusion of oak bark,he describes what was probably the large ciliateSpirostomum ambiguum (12).

In order to describe the anatomical history ofthis fish, I did what I could to find a suitablename, but neither I nor those to whom I showedit could succeed because this insect does notkeep the same appearance for a minute. Thus ina very short period of time one can see it in thevarious forms illustrated in Plate 12 [our Fig.8]....

Pt a.)nfrdetpmailalz et-9. dz bled .

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FIG.8.JTranslation: ~On fishes found in a cold infusion of oak bark."

FIG. 8. Translation: "On fishes found in a cold infusion of oak bark."

Those who saw it in the form represented atA called it Golden Caterpillar.... In its amber-yellow body one sees longitudinal fibers whichreach from one end to the other in betweenwhich one perceives small, rather irregular cor-puscules of unequal size which may be [its]eggs....One sees at B another which was named Sock

or Gaiter, in one of whose extremities I hadgreat difficulty determining the place that thehead might be. However, since this fish oftenshowed a large opening in C which changed inshape at every moment, I thought that I shouldtake this part for the fish's mouth; its lips wereso distended and so mobile that they could beused as a rudder to partially steer its course. Isay partially, because since it seems to advance

and retreat equally well, and turn and turnabout while bending and folding in all imagina-ble ways, this insect must have in itself all thatis necessary to carry out the execution of thesevarious movements.Around its body one notes very small hairs,

among the finest that one can see anywherewhose motion seemed to me hard to detect be-cause their extreme fineness did not permit one

to observe their action easily.Another one which is seen at D, somewhat

shortened, bulging, folded and refolded hasbeen named Horn because of the specific formthat it took for a moment.The one represented at E let itself be seen in

the form of a Bow-net which is a contrivancemade of wicker which one uses to catch fish.

+ irouf anpJ un z on afruldeocerc=.

De bow de cawtne nefI.m i

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FGH is another fish, the part GH resemblinga badly formed leg. The middle of its body seemsto be tied by an invisible ligature.Under the letter I, there is another one which

seems to be of an extraordinary size in relationto the others. There one sees the shape of a foot,a leg and a broken thigh. I named it Buffoonbecause it seems to enjoy the various changeswhich take place so rapidly that one has troublecatching a single pose...The minute these animals die, one sees them

change to white and transparent from the paleyellow that they were before...The one to be seen at 0, I named Elegant,

because to me it seemed to be swimming withsuch grace and to carry itself in such grave andmajestic manner during its various changesthat I could not refuse it that name.

After a dissertation on the mode of imageformation in microscopes and telescopes, inwhich Joblot advances the opinion that objectsare seen by light that enters the microscope andis reflected towards the object, rather than bylight which is refracted by the object, Joblotconcludes:

If I learn that this book had the good fortuneof meeting the favor of the public, I will be wellrecompensed for the labor and the expense thatI have gone to to compose it and this mightencourage me to have another one printed soonwhich will have as a title: New Hypothesis toExplain the Effects of Magnets.

As far as we know, the book on magnets wasnever published.

CONCLUSIONSNo one knowns for sure who invented the

microscope, but Singer (15) came to the conclu-sion that it was most probably the work of acertain Zacharias, son of Jan, and known asZacharias Jansen, of Middelburg, Holland.This first instrument was probably composed oftwo convex lenses and, Singer concluded, wasmade sometime after 1591 and before 1608.

In 1665, Robert Hooke published the firstillustrations of microorganisms (molds), whichhe had seen with a compound microscopeequipped with two lenses. Focusing was accom-plished by a rough screw that moved the wholemicroscope up and down. Light was concen-trated on the object either by "a round globe ofwater, or a very deep clear plano convex glass."The innumerable successes of Leeuwenhoek,using simple microscopes, have been well docu-mented by Dobell (8). His letters describe thepioneer observations of yeasts, protozoa, andbacteria between 1674 and 1683.The next important publication of observa-

tions of microorganisms was that of Joblot. Formost of his observations, made between 1680and 1716, Joblot used microscopes having thegeneral appearance of the one shown in crosssection in Fig. 9. One notes that the specimenwas placed between a barrel, "B" (lined withblack velvet and stoppered by diaphragms toreduce stray light) and the lens, "A," whichcould be moved in and out of focus by the mo-tion of a screw, "D" (activated by a wheel notshown on this picture). The simple microscopeillustrated in "A" could be replaced by com-pound microscopes.The instrument was held by the handle, "C,"

and turned towards the sky for illumination, asshown in Fig. 4, or towards a candle, which wasmore comfortable.

Joblot's instruments represented an advance-ment over those available before him because ofthe quality of the mechanisms permitting pre-cise focusing, the excellent design of his tubulardiaphragms, which eliminated stray light, andthe multitude of his well-planned attachmentsfor mounting the most diverse types of speci-mens (2).

Joblot did not exert the influence that Leeu-wenhoek did, in part because he did not use asgood a method of dissemination of his resultsand also because, for many observations, Leeu-wenhoek rightly deserves priority. In addition,Leeuwenhoek seemed to have been a more pro-found observer ofnature than Joblot. Strangelyenough, Joblot refers only once to Leeuwen-hoek, although he gave credit to many otherpersons in his book. Why ignore Leeuwenhoek?One possible explanation is that Joblot had thehabit of giving direct credit mainly to peoplewith whom he had had direct conversation.Otherwise, he made vague references to what"famous Philosophers" had found. In any case,there is no doubt that Joblot had been stronglyinfluenced by the Dutch microscopist (7).Although for a long time Joblot did not re-

ceive the attention that he deserved, he did notpass unnoticed by his contemporaries. His ob-servations were reported by those who popular-ized microscopy, such as Adams (1) (1747) andBaker (1754) (3), and, of course, if his work hadnot been popular, Briasson would not have pro-ceeded with the second edition of 1754. It seems,however, that at the time more attention wasattached to such curiosities as the moustached"organism" illustrated in Fig. 12 of Plate 6 (ourFig. 6), than to his more sound experiments onspontaneous generation.Konarski (12) made a noble effort to identify

the various "fishes" and "insects" that Joblotdescribed. Some of the organisms are easily

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D

FIG. 9. Cross section through a Joblot microscope. (A) Lens, (B) tubular diaphragm, (C) handle, and (D)focusing screw.

recognized as probably belonging to the generaVorticella, Colpoda, Paramecium, Oxytricha,Spirostomum, and Amphileptus, or as belong-ing among the rotifers or the nematodes. Al-though some of Joblot's fanciful names havesurvived to our days (witness "slipper" for Par-amecium and "swan" for Amphileptus) there islittle to be gained in trying to recognize thespecific identity of most of Joblot's organisms.

Joblot's fame should not be attached so much tothe description of this or that protozoan, butrather to his truly pioneering experiments onmicrobial spontaneous generation. This iswhere he was truly far ahead of his contempor-aries.When Joblot stated that "several famous Phi-

losophers ... have proved by a number of ex-periments ... that all animals . . . come from

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258 LECHEVALIER

eggs," he no doubt had in mind Francesco Rediwho published in 1668 his observations on theproduction of maggots on meat. He showed thatif the meat was protected from the outsideworld by a gauze, maggots would not developbecause the flies could not lay their eggs on themeat, although they gave it a good try by de-positing them on the gauze.To Joblot goes the credit of having been the

first to sterilize infusions by heating, and pro-tecting them from contamination from the air.His experiment was a model followed by allthose who tried to unravel the riddle of sponta-neous generation. From the experimentors ofthe eighteenth century such as Spallanzani,Needham, and Bulliard to those of the nin-teenth century such as Pasteur, Pouchet, andBastian, they all repeated with endless varia-tions the experiments performed on October 13,1711, by the Professor of Perspective and Geom-etry of the French Royal Academy of Paintingand Sculpture.

ACKNOWLEDGMENTSI am grateful to Mary P. Lechevalier for having

reviewed this manuscript.LITERATURE CITED

1. Adams, G. 1747. Micrographia illustrata orthe knowledge of the microscope explained... to which is added a translation of Mr.Joblott's observations on the animalcula...,2nd ed. London.

2. Anonymous. 1914. Old French microscope byJoblot. J. R. Microsc. Soc., p. 297-299.

3. Baker, H. 1754. Le microscope A la portee detout le monde. A. Jombert, Paris.

4. Boyer, J. 1894. Joblot et Baker. Rev. Sci. l(Ser4):283-284.

5. Cazeneuve, P. 1894. La generation spontaneed'apres les livres d'Henry Baker et de Joblot(1754). Rev. Sci. 1(Ser 4):161-166.

6. Clay, R. S., and T. H. Court. 1932. The his-tory of the microscope. Charles Green andCo., London.

7. Dobell, C. 1923. A protozoological bicentenary:Antony van Leeuwenhoek (1632-1723) andLouis Joblot (1645-1723). Parasitology 15:308-319.

8. Dobell, C. 1932. Antony van Leeuwenhoek andhis "little animals." Harcourt, Brace and Co.,New York. (Republished by Dover Publica-tions, Inc., New York, 1960.)

9. Dujardin, F. 1841. Histoire naturelle des zoo-phytes infusoires. Roret, Paris.

10. Fleck, M. L'A. 1876. Quels sont les premiersobservateurs des infusoires? Mem. Acad.Metz. 56(Ser 3, 4):651-652.

11. Hooke, R. 1665. Micrographia or some physio-logical descriptions of minute bodies made bymagnifying glasses with observations and in-quiries thereupon. (Reprinted by Dover Publi-cations, New York, 1961.)

12. Konarski, W. 1895. Un savant barrisien pre-curseur de M. Pasteur. Louis Joblot. 1645-1723. Mem. Soc. Lett. Sci. Art Bar-le-Duc.4:205-333.

13. Ramsbottom, J. 1939. The expanding knowledgeof mycology since Linnaeus. Proc. Linn. Soc.London 151:280-367.

14. Senebier, J. 1787. Introduction du traducteur.In Spallanzani, L'A. Opuscules de physique,animale et veg6tale, vol. I. Duplain, Paris.

15. Singer, C. 1921. Steps leading to the in-vention of the first optical apparatus, p. 385-413. In C. Singer (ed.), Studies in the historyand method of science, vol. 2. ClarendonPress, Oxford.

16. Woodruff, L. L. 1937. Louis Joblot and theprotozoa. Sci. Mon. 44:41-47.

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