BACTERIOLOGICAL REVIEWSVol. 28, No. 1, p. 87-96 March, 1964Copyright © 1964 by the American Society for Microbiology

Printed in U.S.A.

JOHN CRAWFORD AND HIS CONTRIBUTION TO THE DOCTRINE OFCONTAGIUM VIVUMM

RAYMOND N. DOETSCHDepartment of Microbiology, University of Maryland, College Park, Maryland

JOHN CRAWFORD, 1746-1813 ..................................................................... 87THEORIES OF Contagium Vivum...................................... 89CRAWFORD'S THEORY. 90EVALUATION .................................................................................... 94LITERATURE CITED. 96

JOHN CRAWFORD, 1746-1813

The last rearguard action directed against thepowerful onslaught of the "new" anticon-tagionism that swept the United States at thebeginning of the "wonderful century" was foughtalone, by the subject of this essay. Relegated tothe historic dust bin, smothered by the pontificaledicts of Rush and Webster, eclipsed by thespectacular accomplishments of the Europeansires of microbiology 70 years later, we nowremove from the umbra of obscurity an American,dead these last 150 years. We do this not tomagnify his achievements, nor to favorably dis-tort his scientific position, but rather to soundthe opening chords of the American recitative,too infrequently he6ard and too often dismissed.A more auspicious occasion could not be imaginedthan this first symposium on the history ofmicrobiology sponsored by the American Societyfor Microbiology.John Crawford, the second son of a Presby-

terian clergyman, was born in the north of Irelandon 3 May 1746. Several events of his busy lifeare noted here, but more detailed accounts maybe found in biographical sketches by Schultz(14), Cordell (3), and Wilson (17, 18).Crawford was sent to Trinity College, Dublin,

at age 17, and it was there that his medicalstudies began. Between 1772 and 1774 Crawfordobtained valuable experience as ship's surgeon onthe Marquis of Rockingham, which sailed to Bom-bay and Bengal in service of the East IndiaCompany. In 1779 he was appointed surgeon tothe naval hospital on the island of Barbados. Ill-

1 A contribution to the Symposium on Historyof Microbiology, presented at the Annual Meetingof the American Society for Microbiology, Cleve-land, Ohio, 8 May 1963, with Raymond N. Doetschas convener.

ness forced his retirement to England in 1782.and, although he returned to the West Indiesafter recovering, he accepted a position asSurgeon-Major in the Dutch Colony of Demerarawhen offered to him in 1790.

In 1794 Crawford's health again failed, and hereturned to England and thence to Holland andthe University of Leyden. He received his M.D.degree from this institution, one of the leadingmedical centers of its time, in the same year. Itmay be noted, en passant, that Crawford's medi-cal degree from St. Andrew's is dated 1791. Craw-ford detailed the problems of colonists (includinghimself) in adjusting to their new environmentalconditions in an essay entitled, "A LetterAddressed to Lieutenant-General Mathew on theMeans of Preventing, the Method of Treating,and the Origin of Diseases Most Prevalent andwhich Prove Most Destructive to the Natives ofCold Climates Visiting or Residing in WarmCountries" (unpublished manuscript in thelibrary of the Medical and Chirurgical Faculty inBaltimore, Md.).

In 1796 Crawford emigrated to Baltimore, Md.,a decision encouraged by his brother-in-law,John O'Donnell, a prosperous merchant of thecity. In that year Baltimore had an estimatedpopulation of 20,000, of whom 27 were physicians.Crawford immediately plunged into the publicaffairs of Baltimore as well as into the attendantmedical scene. He began a continuing correspond-ence with Benjamin Rush (8) of Philadelphia in1797, and in 1800 John Ring (13) of London senthim samples of smallpox vaccine. Crawford andBenjamin Waterhouse of Cambridge, Mass., weretherefore the first to employ this material in theUnited States. Crawford apparently was not suc-cessful in using this vaccine, and in any case thereis no evidence that he preceded Waterhouse in

87

on June 11, 2020 by guesthttp://m

mbr.asm

.org/D

ownloaded from

BACTERIOL. REV.

FIG. 1. John Crawford, 1746-1813. An original engraving commissioned as a memorial by the CassiaLodge of the Masonic Order.

this experiment. In the same year, Crawford energy, he aided in the establishment of suchseconded the Maryland Society for Promoting Institutions as the Maryland Penitentiary, theUseful Knowledge, and subsequently he was Bible Society of Baltimore, the Baltimoreelected Grand Master of the Masonic Order of Library, and the Baltimore General Dispensary,Maryland. A man of apparently inexhaustible and, in addition, he was Chairman of the Medical

88 DOETSCH

..1.

?"; it's' '. .-n ...7`i.'--,-f 9-

on June 11, 2020 by guesthttp://m

mbr.asm

.org/D

ownloaded from

JOHN CRAWFORD AND CONTA GIUU VIVUM18

Faculty of Baltimore, Vice-President of theMedical Society of Baltimore, and consultingphysician to the Board of Health and the CityHospital.

In 1804 Crawford began editing a small weeklymagazine entitled The Companion and WeeklyMiscellany, using the romantic pseudonym,"Edward Easy, Esq." In the latter part of 1806,his daughter, Eliza, assumed the editorship(thereby becoming the second woman editor inthe United States) under the improbable name ofBeatrice Ironside. The title of the magazine waschanged to The Observer and Repertory of Originaland Selected Essays in Verse and Prose on Topicsof Polite Literature, but generally it was referred toas The Observer. This literary adventure, withCrawford as a constant contributor, concluded on26 December 1807.

Crawford was lecturer in natural history at theCollege of Medicine of Maryland (later the Uni-versity of Maryland) for a brief time in 1812. Hedied on 9 May 1813 in his 67th year, and wasburied in the Presbyterian cemetery at Fayetteand Greene Streets in Baltimore. Shortly there-after, his medical library, which included works ofBonnet, Kircher, Linnaeus, Redi, Plenciz, Swam-merdam, and others, and apparently one of thebest in the United States at that time, was soldto the University of Maryland for $500, a sumprivately raised by the faculty.

Crawford's contributions to the theory ofcontagium vivum were first published in a series of"literary" articles (4, 5) in The Observer in 1807,and more formally in 1809 in Tobias Watkins'The Baltimore Medical and Physical Recorder (6).This was the first medical journal published inMaryland and the third in the United States. Itwas Watkins who delivered the eulogium onCrawford, his brother Mason, on 24 June 1813,and we may surmise that there were close pro-fessional and social ties between them.

Before considering the substance of Crawford'swork in detail, a general, if necessarily brief, re-view of some theories of contagium vivum extantat this time would perhaps be helpful in apprais-ing its merits.

THEORIES OF Contagium VivumAround 60 B.C. Lucius Junius Mloderatus

Columella, in his treatise De Re Rustica, warnedagainst constructing dwellings near swampyplaces since there arise in these locations flying

animals possessing poisonous stings. In the samevein, Marcus Terentius Varro stated that ifswamp land becomes dry, the dust therefrom maycontain invisible agents which enter the mouth ornose and cause "obstinate diseases." TheseRoman writings are in the vanguard of a long lineof theoretical speculations and conjectures con-cerning the possibility of a contagium animatumor contagium vivum. None of these theories wasaccompanied by a shred of experimental evi-dence, and the great bulk of these were based, atbest, on empirical observation.

There were a number of theories expounded onin the 16th, 17th, and 18th centuries concerningthe possibilities of animate contagious agents. In1557 Geronimo Cardano (Jerome Cardan) sug-gested that the "seeds of disease" were living andthat they reproduced in the manner of otherminute living beings. Following him, AlessandroBenedicto (Alexander Benedict) in 1608 describedminute "'lumbrici' on the teeth, in the lungs andkidneys, and on the skin." Singer and Singer (16)wrote that "he appears to have been quitefamiliar with living creatures as a cause of diseaseand he certainly knew of the organisms ofscabies." Nearly 50 years later (1650), AugustHauptmann argued that fevers were caused byminute organisms of the nature of worms or theireggs. Christian Lange also believed that diseaseswere due to the entrance of minute living agentsinto the body. This view was documented atlength in Lange's huge (698 pages), posthumouslypublished, Pathologia Animata (1688). Con-temporaneous with Lange was the mystical andmetaphysical Jesuit, Athanasius Kircher. In con-sidering the cause of plague, Kircher referred it toan effluvium consisting of imperceptibly minuteliving bodies. It is possible that this remarkableman was the first to use a microscope in studyingdisease, and, in any event, he reported that theblood of plague victims was invaded with numer-ous microscopic "worms." Garrison (10) wrotethat Kircher "was undoubtedly the first to statein exl)licit terms the doctrine of a contagiumanimatum as the cause of infectious disease."

In 1717, Giovanni Maria Lancisi's importanttreatise in the history of insects as disease agentswas published. In this work, De Noxiis PaludumEffluviis Eorumque Remediis, Lancisi consideredthe causes of marsh fevers. He wrote, ". . . if I,without experiments, venture to affirm that, incamp fevers of this sort, the worms,penetrate and

VO*L. 28, 1964 89

on June 11, 2020 by guesthttp://m

mbr.asm

.org/D

ownloaded from

BACTERIOL. REV.

ascend the blood vessels . .. it would be necessarythat the blood of those suffering from marshfevers should be let, which medical reasonseldom admits, and to carefully examine the bloodwith a microscope for insects of this kind, if suchthere be. But, although worms might be seen indrawn human blood, it would still be doubtfulthat these insects should be considered the causeof the evil; or whether, which I consider moreprobably, it is the product of the breaking downof the fluids; whence all minute ovules, after theyhave been wrapped up in particles of the blood,are set free or are supplied from the externalair....

In 1720 the doctrine that invisible insects orworms could be the causes of disease was ad-vanced by Richard Bradley. He wrote a tract,published in London, entitled "The Plague ofMarseilles Considered." According to Singer andSinger (16) it was the best attempt to solve theproblem of infection before Pasteur. The little-known English physician, Benjamin Marten, pre-sented a remarkably accurate analysis of thepropagation of tuberculosis in 1720. He statedthat the cause of this disease "may possibly besome certain species of animalcula or wonderfullyminute living creatures that by their peculiarshape or disagreeable parts are inimicable to ournature but however capable of existing in ourjuices and vessels ... or else generated there fromtheir proper ova or eggs . . . which possibly beingcarried about by the air may be immediately con-veyed to the lungs by that (air) we draw in...."Although generally ignored by modern historians,Marten's book was sufficiently popular in its dayto be printed in a second edition in 1722. The titleof this unusual work was, "A New Theory of Con-sumptions; More Especially of a Phthisis or Con-sumption of the Lungs."

In America, apparently the only one prior toCrawford to consider the possibility of a con-

tagium animatum was the Reverend CottonMather. In his Angel of Bethesda, Visiting theInvalids of a Miserable World, published in 1722,Mather assumed that minute "worms" were thecauses of disease. He speculated that a safe andpotent worm-killer would perhaps be an excellentcure for many diseases.

Finally, there is Marcus Antonius Plenciz'Opera M1edico-Physica, published in 1762. In thiswork he envisioned airborne seeds of contagionwhich germinated to form animalcules as well as

leeches, flies, beetles, or gnats. Some of theanimalcules were postulated to be invisible.

In a recent essay, Shryock (15) concluded thatby the 1740's, "interest in the animalcular theoryhad now largely disappeared, for reasons whichmerit some attention in passing. This theory hadbeen based on experience with large, pathogenicparasites and the revelation by microscopes ofminute organisms which might play a similar role.Epidemiologic evidence suggested as much andlent the theory some plausibility, but laboratoryverification was needed and could not be securedwith the scopes [sic] and techniques then avail-able. Even if techniques had been adequate, theidentification of most infectious diseases was notyet specific enough to enable scientists to knowwhat organisms they were looking for. A Pasteurwould have found nothing had he searched for'germs' causing such vague conditions as 'biliousfever' and 'inflammation of the chest'."

CRAWFORD'S THEORY

Crawford's theory appeared in The Observer inthe form of two long essays. The first, "Remarkson quarantine suggested by Dr. Caldwell'soration," consisted of 71 pages distributed intoshort articles of 3 to 7 pages each, appearing in 14separate issues. The second, "Dr. Crawford'stheory and an application of it to the treatmentof disease," followed, and it consisted of 48 pagesappearing in 11 separate issues. The Observer wasin existence from 29 November 1806 to 26December 1807; thus, a Crawford contribution isfound in approximately half the issues published.

It is Futcher's (9) opinion that, since Craw-ford's theory was regarded as ridiculous by hiscolleagues, he used a literary medium rather thanrisk rejection from a medical journal. Futcheralso suggests that whenever Crawford's daughter,Eliza (Beatrice Ironside, the Editor), was short ofcopy, she approached her father for more on the"quarantine business." Crawford, however,wrote, "In the mode I have adopted for convey-ing my sentiments to the publick, I deviate verymuch from that which has been usually pursued.AiIedical information has been hitherto generallycommunicated in medical language, and has beenonly intended for the medical eye. In the presentcase, such a mode would be very unsuitable. It isof the highest importance that the communityat large should be made acquainted with what isso materially the concern of every individual, and

90 DOETSCH

on June 11, 2020 by guesthttp://m

mbr.asm

.org/D

ownloaded from

JOHN CRAWFORD AND CONTAGIUM VIVUM

it cannot fail to be highly advantageous, both tothe physician and to the patient, to be united intheir opinion as to the cause of disease" (Ob-server 2:183). Then he adds, wistfully, "I mayfail to attract attention in the commencement ofmy labours; but I shall persevere, and shalladduce such arguments as I persuade myself, willat length over come every obstacle. My great aimis to discover truth, and in the discovery, to pro-mote the happiness of my fellow men.... It re-quires time and examination to be known; butwhen it is known its force is irresistible."Crawford begins by stating that, "the all-wise

and beneficient author of our existence has notexercised such wanton cruelty toward us as torender the cause of such dreadful calamitieseither visible or tangible; discoverable by any ofour senses." He holds that, as we do not know theorigin of such calamities, it is futile to attemptquarantine measures. In an analysis of the Balti-more yellow fever epidemics of 1797 and 1800,Crawford showed that there was a marked geo-graphical limitation to the occurrence of this dis-ease, and that fact, together with other observa-tions concerning its incidence, "militated verystrongly against the existence of any species ofgas or modification of air, as a cause of epidemics... The yellow fever with us has always had alocal residence."

There is a second reason for Crawford's beliefin the futility of quarantine measures. He followedMalthus in considering epidemics and wars to beuseful (albeit dreadful) controls in preventingoverpopulation. This point is further fit into thestructure of his theory in a most curious, onemight almost say Darwinian, manner. A basictenet in Crawford's view was that all living beingsare subject to common natural laws regardingtheir generation, nutrition, and death. He says,"If we can be persuaded that we are necessarilyamenable to the common law, then as organs areconspicuous in one animal, that are scarcelyvisible in another, so the manner in which thetribute of life is paid by one species, may beobvious, whilst in another species it is completelyconcealed." He points out that over-reproductionmakes one species a source of food for another,thereby maintaining an equilibrium. Man is sub-ject to the same laws, and, in common with allother living beings, he has open and concealedenemies. It is man's invisible enemies that at-

tack him and cause infectious disease, but he isunaware of the moment when this occurs.

According to Crawford, the other possibilityconcerning dissemination of epidemic disease,having ruled out air, aerial vapors, and gases, isthat of direct contact between a diseased andhealthy individual. Smallpox was considered asa striking example of such a disease. Crawford re-calls the detailed investigation by James Sims of asmallpox epidemic in Tyrone County, Ireland.Sims observed that numerous cases of smallpoxoccurred simultaneously throughout the countyamong persons having no contact, and thereforeother explanations of the incidence of this diseasewere required.

Crawford then focused attention on thefascinating machinations of the insect world. Herehe reveals both depth and scope of learning, andhe constructs a forceful, if unexpected, analogybetween the silent, savage struggles among in-sects and the cause of human infectious disease.This exposition is logical, detailed, and closelyknit, and there is nothing similar to it by even themost ardent contagionist preceding him. This is apersuasive reason why Crawford ought to berescued from history's limbo. His thesis is that"by diligently comparing the relative propertiesof things that are exposed to view, he can, with amoral certainty, form conclusions that reach farbeyond this limited evidence." The first examplechosen is that of the plant aphids (pucerons).Crawford noted that some insects deposit theireggs on plant leaves colonized by aphids. Whenthese eggs hatch, the young devour the aphids,and it appears that the latter are wholly ignorantof the existence of their enemies. An examinationof the curious ways of the corn weevil, capricornbeetle, nut weevil, wood piercer, lady bird beetle,and lymexelon beetle shows that these insects arecapable of introducing their eggs into or on thesubstance of other living plants in a variety ofingenious ways.A classic case, in Crawford's view, is that illus-

trated by the ichneumon fly. These insects deposittheir eggs in the bodies of other living insects,especially caterpillars. The ichneumon larvae arefor the most part internal parasites, and theyultimately cause the death of their host. Equallyforceful is the example of the gadfly, and its habitof depositing its eggs in the bodies of sheep,cattle, and horses. The larvae, known as "bots,"produce painful tumors and even death in the

91OOL. 28, 1964

on June 11, 2020 by guesthttp://m

mbr.asm

.org/D

ownloaded from

BACTERIOL. REV.

afflicted animals. Man himself does not escape thedepredations of these insects.

After these detailed considerations, Crawfordreiterates the conclusion that: "The assailed areso constructed as to be unconscious of the attackof the assailant. If this is inseparable from theoeconomy of nature, it necessarily follows thatman must be subject to the depredations ofoestri, ichneumons, ... and perhaps, thousandsof others, which the senses, aided by the di-rections of a correct understanding, may be ableto trace in a way that will fall very little short ofabsolute demonstration. Insects of almost everydescription, have been found alive in differentparts of the human system . . . but how they haveobtained admission into it, has been hitherto un-explained." Further on he suggests, "If we canonce be satisfied that the cause of death, obviousin any one creature, must resemble the cause pro-ducing death in every other, we shall be enabledto form conclusions respecting our own fate, thatwill generally give satisfaction. If this reasoningis just, it of necessity follows that as the plagueof caterpillars, pucerons, and of all insect tribes,is the ichneumon. . . so the plague, yellow andevery other fever, and every other disease we ex-perience, must be occasioned by eggs insinuated,without our knowledge, into our bodies, externallyor internally, or from eggs placed near our habita-tions which, when hatched, in either case preyupon us by parts... ." Finally, a Parthian shot atquarantine, "If diseases, without any exception,either as to object or nature, are occasioned by aliving principle which attacks and preys upon itsfellow mortal, how can a quarantine obviate thedifficulty? If the origin of all diseases is a livingprinciple, possessed of the power of removing fromone place to another, and as our senses, it isalleged, are incapable of discerning it, how is itpossible that one can devise any barrier againstthe invasion which is invisible?"

Crawford replied to Mead's disclaimer that,"the theory that existence of insect eggs, whenhatched, causes disease is not grounded upon nomanner of observation," by asking upon whatobservations the existence of an "active principle"generated from corruption was founded. He holdsthat eggs whose existence is certain, are easy touse for explaining disease causation, whereas"active substance" is not.

Crawford, following his experiences with yellowfever, and Sims' with smallpox, did not believe

that infectious disease may be spread directlyfrom person to person. He argued, "If, as alleged,it is an host of flies which deposit their eggs eitheron our bodies, or near our bodies, so that theirlarvae can conveniently attack us, then all diffi-culty vanishes. Then they may either proceedfrom one body to another, or attack great num-bers of bodies at the same time, and as otherlarvae herd together, we may readily see how itcomes to pass that disease rages more in one partthan in another, and at different parts in succes-sion."

In "Dr. Crawford's Theory and an Applicationof It to the Treatment of Disease," a super-ficially different approach is made, but upon ex-amination it is apparent that large portions arerepetitious of the first essay. Emphasis is placed,not on the foibles of the insect world, but uponthe writings of 17th and 18th century philoso-phers-natural and otherwise-whose work iscited as buttressing Crawford's theory. In addi-tion, there are numerous passages in which Craw-ford inveighs against the narrow and closedminds of the local medical persons who oppose histheory: "It is by collision alone that truth can bediscovered, it will, in the end triumph over everyantagonist. If this theory, which I have at-tempted to reduce to its intrinsic simplicity,proves to be in unison with the undeviating orderof nature, the more profoundly it is investigated,the more certainly it will lead to correct views ofthe origin of diseases, of the method of treatingthem, and of the manner in which medicinesoperate. It will also lead to shew where it happensthat they so often fail, are sometimes injurious,and so frequently effect the purpose for whichthey were designed. Is there any knowledge moredesirable than what is here proposed? To beemancipated from the wilderness of darkness bywhich every thing relating to diseases and tomedicines has been hitherto obscured, must ap-pear highly interesting. These involve our dear-est, our very nearest concerns, and ought to be anobject of universal enquiry. Hitherto thesepursuits had been confined to a particular class ofmen, and to men who derived from them theirsupport. Such men are always trammeled bypublick opinion, and of this they are generally theslaves. Very few indeed dare to deviate from it,because all who have. were the victims of theirtemerity. They were either vilified, cruellypersecuted, or sunk into neglect. The few sup-

92 DOETSCH

on June 11, 2020 by guesthttp://m

mbr.asm

.org/D

ownloaded from

JOHN CRAWFORD AND CONTAGIUMVIVUM9

porters of the theory in question, have con-spicuously experienced this fate; they have eitherbeen stigmatized as quacks, or considered as wildvisionaries, and treated with contempt" (Ob-server 2:250). There is no doubt that Crawfordwas one so treated by his Baltimore colleagues.Further in this essay he says, "In the pursuit ofthis enquiry, I well know that I shall expose my-self to obloquy. I have already experienced it ex-tensively; I have been deemed an innovator; I amaccused of having descended from the dignity ofmy species, and placing myself on a level withthe most ignoble of creation. What others mayconsider as a degradation, I esteem of high value.To be enabled to see with the eyes of my under-standing what is hidden from every other speciesof terrestrial being, must be a high privilege; to becapable of tracing from the lowest, what mostnearly concerns the highest order, and what isbeyond the reach of every other order, must be asubject of exultation" (Observer 2:311). There ismuch more of this in the same key throughoutthis paper.

Crawford's main points concerning the cause ofinfectious disease, as expressed in these twoessays, may be summarized: (i) Man's ultimatefate is the same as that of every other livingcreature, that is, he is a part of nature. (ii) Someanimals derive their sustenance from plants,whereas others derive their sole support frompreying on their fellow creatures. (iii) Among themost marvelous works of creation are the minutestbeings, and in every instance they are employedto divest the superabundance (due to over-repro-duction) of those that are a larger size. If we wereacquainted with the manner in which this iseffected, it would afford a chance for detectingthis agency in every other species. (iv) In a multi-tude of instances, the depredators are wholly un-known to those on whom they prey. Man hasinvisible, insectlike enemies, numerous and in-capable of detection by ordinary senses. (v) In-sects and their larvae, because of their mobilityand other characteristic habits, are most likely acause of infectious disease, and their mode ofoperation may be supposed to be very muchsimilar to that of the ichneumon fly and thegadfly.

In addition to the obloquy and derision thatCrawford suffered at the hands of his Baltimorecolleagues, his "Observer" essays were moresoberly reviewed (2) in the pages of Mitchell and

Miller's The Medical Repository and Review ofAmerican Publication on Medicine, Surgery, andthe Auxiliary Branches of Science, for the year1807. After briefly alluding to Crawford's beliefin the "animalcular hypothesis" and reviewinghis contentions that specific diseases were causedby specific insects, the review concludes with thedry statement, "For ourselves, who are believersin the chemical theory, we must refer such of ourreaders as wish further proofs of Doctor Craw-ford's learning and ingenuity, to his original dis-sertation." And prior to this, in a written letterto Benjamin Rush in January, 1806, Crawfordcomplained that, "The premature disclosure (byhimself or others) of my opinions has afforded ameans to the envious and malignant to prejudicethose I had every reason for valuing myself on,so as to deprive me of all the valuable practice inthis City.... There is one consolation which Ifelt. I am convinced that we are both of us inearnest in our pursuit of truth, and in so far as ourroad is the same, we shall necessarily accord.Where we take different directions, I am per-suaded also that we shall cordially agree to differ,nor either to hesitate to adopt what appears to uscorrect . . ." Rush's concepts were not changed byCrawford's theory, either before or after its ap-pearance in print.

Crawford gamely persisted in attempting togain notice of his theory when in 1809 he wrote a41-page essay, published in three parts, for TobiasWatkins' short-lived The Baltimore Medical andPhysical Recorder. Entitled "Observations on theseats and causes of disease," this work is a formaleffort directed to the medical practitioner of hisday. The first part, based partly on his Demeraraexperiences, considers the relationships existingbetween the actual origin of a disease process andthe supposed location based on symptoms. Thesecond and third parts are mostly repetitious, withsome additional citations, more examples fromthe animal kingdom, and rewording of the ma-terial in The Observer essays. Crawford maintainsthat there is a plant provided for every animaldestined to feed on it, to which it ever resorts inpreference. So also, every plant has its suitableinsect host which restrains its inordinate luxuri-ance. Here, there seems to be a hint of what isdescribed today as "species specificity." Thepedal point of Crawford's opus continues tosound: "whatever has been created, possesses andexercises the powers of multiplication beyond the

93VOL. 28, 1964

on June 11, 2020 by guesthttp://m

mbr.asm

.org/D

ownloaded from

BACTERIOL. REV.

means of support, and that the exigencies ofwhich this want of support must be the conse-quence, has been obviated by constituting one ormore species as food for each other."There is appended to this essay a letter dated

29 March 1806, from Clement Stanford, concern-ing discovery of numerous "black bugs andworms" in the stomach contents of a female pa-tient. The letter was addressed to WilliamWinder, Esq., of Baltimore [Oliver (12) has dis-covered a letter to General William HenryWinder on another subject] and in it Stanfordsays that, "I am willing to do everything in mypower to the advancement of Dr. Crawford'swork of which you make mention, although un-acquainted with that gentleman." AlthoughCrawford promised to "hereafter produce numer-ous proofs by which [the theory] is sustained,"the above case is the only one cited in his writings.In 1811, Crawford commissioned Edward J.

Coale to publish a 51-page book (7) entitled, ALecture, Introductory to a Course of Lectures, onthe Cause, Seat and Cure of Diseases. Proposed tobe Delivered in the City of Baltimore. Theselectures were to be given at his home at HanoverStreet in the fall of 1811, but apparently only onelecture was given. The title suggests the substanceof the "Observer" and "Recorder" essays, andindeed the introductory itself is repetitive, dis-cursive, and rambling. In 1812, the regents of theMedical College gave Crawford an appointmentwith the title "Lecturer on Natural History," butthis position was shortly abandoned. He wroteshortly thereafter to Rush that his introductorylecture was poorly received, and that he wastreated ungraciously and with illiberality.

Crawford died a disappointed, if undefeated,man. He was heavily in debt, a fact he hadmentioned previously (16 November 1808) toBenjamin Rush. He "had lost all his business bypropagating an unpopular opinion in medicine,namely that all diseases were occasioned byanimalculae."

EVALUATION

Most historians have ignored Crawford's work,and, in those rare cases when he is cited, asentence usually serves to dismiss both him andhis theory. Although it might be argued thatCrawford is, in fact, a transplanted European andnot an American, I maintain that, since his con-tributions were brought to fruition on the

American scene, we may properly consider himto be an American.

It may be added that American work in thisfield prior to the Civil War is not documented "indepth." In reintroducing the historic element tothis era, it may be instructive to trace the originsof Crawford's theory, a task easily accomplishedin his case. It was in Demerara that there wereunlimited opportunities for postmortem examina-tions of persons dead from a variety of diseases.Crawford gradually was forced to the positionthat current medical theories concerning diseasesymptoms and origins could not be reconciledwith his practical experiences, and thus began thesearch for a more satisfactory explanation. InCrawford's words, ". . . I clearly saw that someother plan must be adopted for the explanation ofthese appearances, than had been hithertoproposed. I perceived a number of changes in thestructure of various parts, which it was evident,could not have been effected by any power thatcould belong to these parts, and that they musthave been the work of some influence which wasof a foreign nature. I was attracted by the swarmsof very minute flies which were visible onlywhen the declining sun emanated its rays in anoblique direction, and, as these were only dis-tinguishable at some distance from me, I askedmyself whether the atmosphere by which I wassurrounded and continually inhaling, could beless replete with these little beings? If this wereso, it necessarily followed that I must be receivingthem with my breath in multitudes. My next con-sideration was whether, when admitted into mylungs it was impossible they could be wholly in-noxious to my system" (Observer 1:181-182).

Later, discussions in Leyden revealed to Craw-ford that a number of authors had suggested,either casually or seriously, that insects might bethe cause of infectious disease. Crawford took upthe burden of elucidating the detailed mechanicsof this process and of supplying proofs of its cor-rectness. There is more to Crawford's theory thanthe bare statement, "he was also one of those whobelieved that insects cause infectious disease." Itis to Crawford's merit that, by carefully reasonedarguments, together with such field observationsas were possible, he was able to erect a theoreticalstructure to explain how infectious diseases resultas a natural process, rather than as some ac-cidental concatenation of chemical phenomena.This is why Crawford analyzed in such pains-

94 DOETSCH

on June 11, 2020 by guesthttp://m

mbr.asm

.org/D

ownloaded from

JOHN CRAWFORD AND CONTAGIUM VIVUM

taking detail insect-plant and insect-animal rela-tionships. His concept of nature was that of aperfectly coordinated mechanism in which eachspecies performed a specific function and occupieda specific niche. Infectious disease for Crawfordwas always the resultant of a natural process withultimate positive good in the sense of Malthus,for the race of mankind, even though individualsmight suffer or die.

It is curious that Crawford's preoccupationwith minute insects seems to have blinded him toconsideration of a yet lower level of minute organ-isms, that is, microorganisms. He seemed satis-fied that insects or their larvae (especially thoseso minute as to be invisible) were the agents ofinfectious disease, and animalculae, sernsu stricto,were never considered. Crawford's failure tosupply convincing proofs for his theory made hisposition untenable; yet, he never appeared toactively seek out, by any means at his disposal,the experimental evidence so glaringly lacking.One might have imagined that Crawford wouldhave received some support for his stand againstquarantine. After all, Baltimore was a mercantileand maritime city, and bureaucratic interferencewith the business of a growing and powerfulmerchant class was not to be brooked. Acker-knecht (1) maintained that the anticontagionistswere usually liberals and reformers, but Crawfordreceived no support from these groups during hisstruggle.

Crawford's essays are tinctured throughoutwith the same altruistic theme that characterizedhis public career. There is no doubt that his un-orthodox views had a severely adverse effect onhis professional and personal affairs. We mustadmire him for not yielding to the conformistpressures that must have assailed him from allquarters. He was 60 years of age when he beganto promulgate his views publicly; one would haveimagined that such missionary zeal would charac-terize a rather younger man.As to the theory itself, it was sorely out of joint

with the times. In his masterful essay, Acker-knecht (1) has shown that anticontagionistdoctrines soared highest before their final smash-ing refutation at the hands of Koch, Pasteur,Lister, and Tyndall. American medical thoughtand theory in 1800 was essentially European, andthe professionals of Baltimore fully echoed thosesentiments. Here, for example, are the words ofHoratio Gates Jameson (11), written in 1817

about Crawford's "animalcular hypothesis," ". . .it does not seem to merit notice, yet the many im-perfections of diversities of opinion are sufficient. . . to humble the most aspiring genius into acautious reserve how he attempts to trample onopinions supposed to be exploded.... I maysafely say that with our present knowledge of thissubject, nothing can be said of any practical use."

Crawford's observations on the geographicallimitations of yellow fever were sound. We knownow that some insect-borne diseases are not onlylimited by the distribution of their vectors (yellowfever, malaria, tick-borne diseases), but they arenot transmitted from an infected individual to ahealthy one. The relationships of insects andticks as vectors of disease were brilliantly workedout later by Manson, Finlay, Smith, and Ross.Crawford's idea on the specificity of infectious dis-ease agents also was sound. His arguments basedon analogy were cleverly and honestly conceived,and were thoroughly consistent with the scientificknowledge of his time. He clearly foresaw the"struggle for existence" that Darwin advocated53 years later. His philosophy was completelyfurnished with Malthusian overtones, and doubt-less he adopted his views shortly after "The Essayon Population" was published in 1798. The mag-nitude of the events occurring in the War of 1812,and the short life, poor distribution, and unknownquality of the journals publishing Crawford'swork, coupled with failure to attract students ordisciples, signified that his unhappy death closedwhat might have been an auspicuous beginningchapter in the history of American medicine. Asit was, 19 years elapsed before Daniel Drakeseriously reintroduced the question of the rela-tionship between insects and disease, and 35years passed before Josiah Clark Nott came closeto uncovering the connection between yellowfever and mosquitoes.Crawford may not have deserved the epithet

"great," but he was a courageous humanist hack-ing out a lonely path in a hostile and unexploredjungle; although he traveled but a short distance,he was going in the right direction.

ADDENDUM IN PROOF

I have recently discovered an unpublishedMlaster's thesis by W. B. Walker (M.A. Thesis,Johns Hopkins University, Baltimore, Md.).This work, written in 1951, and titled "Dr. JohnCrawford of Baltimore (1746-1813)," has many

95'OL. 28, 196

on June 11, 2020 by guesthttp://m

mbr.asm

.org/D

ownloaded from

BACTERIOL. REV.

additional details concerning other facets ofCrawford's medical work; it should be seen byanyone interested in the history of this period.

ACKNOWLEDGMENTS

This work was supported in part by a grant(GS-64) from the National Science Foundation,Office of Social Sciences, History and Philosophyof Science Program.

LITERATURE CITED

1. ACKERKNECHT, E. H. 1948. Anti-contagionismbetween 1821 and 1867. Bull. Hist. Med. 22:562-593.

2. ANONYMOUS. 1807. Crawford's animalcularhypothesis of epidemics. Med. Repository5:86-87. 0

3. CORDELL, E. F. 1903. The medical annals ofMaryland 1799-1899, p. 758-770. TheWilliams & Wilkins Co., Baltimore.

4. CRAWFORD, J. 1807. Remarks on quarantinesuggested by Dr. Caldwell's oration. Ob-server 1:248-255, 262-266, 283-286, 299-302,314-318, 325-330, 344-348, 373-377, 404-408;2:7-10, 20-25, 33-39, 49-54, 65-70.

5.CRAWFORD, J. 1807. Dr. Crawford's theoryand an application of it to the treatment ofdisease. Observer 2:181-184, 200-203, 217-220,231-232, 248-250, 265-267, 278-281, 309-311,326-329, 339-342, 407-419.

6. CRAWFORD, J. 1809. Observations on the seatsand causes of disease. Baltimore Med. Phys.Recorder 1:40-52, 81-92, 206-221.

7. CRAWFORD, J. 1811. A lecture, introductory toa course of lectures, on the cause, seat andcure of diseases. Proposed to be delivered inthe city of Baltimore. Edward J. Coale,Baltimore.

8. CRAWFORD, J. Unpublished letters to Dr.Benjamin Rush of Philadelphia. Seventeenmss. in Library Company of Philadelphia,Pa.

9. FUTCHER, P. H. 1936. Notes on insectcontagion. Bull. Hist. Med. 4:536-558.

10. GARRISON, F. H. 1929. An introduction to thehistory of medicine, 4th ed. W. B. SaundersCo., Philadelphia.

11. JAMESON, H. G. 1817. Lectures on fevers in gen-eral, in which their causes, symptoms, andsanitives are reviewed. With critical obser-vations on causes, pathology, animal life,etc. John D. Toy, Baltimore.

12. OLIVER, J. R. 1936. An unpublished autographletter from Dr. John Crawford (1746-1813)to General William Henry Winder. Bull.Hist. Med. 4:145-151.

13. RING, J. 1801. Treatise on the cow pox; con-taining the history of vaccine inoculation... in 2 parts, p. 459. J. and T. Carpenter,London.

14. SCHULTZ, E. T. 1885. History of freemasonryin Maryland, vol. 2, p. 297-307. J. H.Medairy & Co., Baltimore.

15. SHRYOCK, R. H. 1960. Medicine and society inAmerica 1660-1860. New York UniversityPress, New York.

16. SINGER, C., AND D. SINGER. 1914. The develop-ment of the doctrine of contagium vivum.XVII Intern. Congr. Med., London, 1913.Section XXIII. History of Medicine, p.187-206.

17. WILSON, J. E. 1940. Dr. John Crawford, 1746-1813. Bull. School Med. (Univ. Md.) 25:116-132.

18. WILSON, J. E. 1942. An early Baltimore physi-cian and his medical library. Ann. Med.Hist. 4:63-80.

96 DOETSCH

on June 11, 2020 by guesthttp://m

mbr.asm

.org/D

ownloaded from