modern science of bacteriology.Like all great men, Koch attracted

around him a host of billiant pupils ofthe calibre of Von Behring Kitasato,Gaffky, Loffler, Welch and others, allof whom made important discoverieswhich have made them immortal. Anysingle discovery of Koch- the discov-ery of the tubercle bacillus being out-standing - would have ensured him aplace in medical history, but when oneconsiders his total achievement, hestands out as one of the medical giantsof all time and medicine and humanityat large remain for ever indebted tohim.

B I B L I O G R A P H Y

BECKER, w. (1894) Biography of Robert Koch.Berlin.

BROWN, L. (1935) Robert Koch: An Americantribute. Ann. Med. Hist. 7, 93, 292, 385.

FORD, W.W. (1911) Life and work of RobertKoch. Johns Hopkins Hosp. Bull. 22, 415.

GAFFKY, G. (1910) Robert Koch. Dt. med.Wschr. 36, 2321.

KNOPF, S.A. (1911) Robert Koch: The father ofthe modern science of tuberculosis. JohnsHopkins Hosp. Bull. 22, 425.

PALTAUF, R.(1903) Wien. klin. Wschr. 16, 1377.WEBB, G.B. (1932) Robert Koch (On occasion of

Jubilee of discovery of tubercle bacillus).Ann. Med. Hist. 4, 509.

WEZEL, K. (1912) Biography of Robert Koch.Berlin.

A list of Koch's publications and ofthe contents of the Koch MemorialCollection in Berlin can be obtainedfrom the author on request.

Dr. R.G. Thomson is responsiblefor the "Historical Column" cur-recently being featured in the Cana-dian Veterinary Journal. Readersare invited to send items, papers,suggestions, pictures, comments,etc., to Dr. Thomson, Departmentof Veterinary Pathology, WesternCollege of Veterinary Medicine,University of Saskatchewan, Sas-katoon, Saskatchewan S7N OWO

Robert Koch: Centenary of the Discovery of theTubercle Bacillus, 1882

ALEX SAKULA

From Redhill General Hospital, Surrey

ABSTRACT

This is an account of the life and workof Robert Koch (1843-1910), NobelLaureate in Medicine and a founder ofthe science of bacteriology. In particu-lar, Koch's researches into tuberculo-sis are described- the discovery of thetubercle bacillus, the controversyregarding the human and bovinetypes, the Koch phenomenon, and theintroduction of tuberculin, whichproved to be ineffective as a cure butbecame important as a diagnostic toolin the management of tuberculosis. Byhis achievements in this field, Kochmay be considered to be the father ofthe scientific study of tuberculosis. Onthe occasion of the centenary ofKoch's discovery of the tubercle bacil-lus in 1882, we pay tribute to this greatGerman master of medicine.

Robert Koch's discovery of the tub-ercle bacillus in 1882 was a major eventin the history of medicine, a turningpoint in our understanding and con-quest of that deadly disease which had

plagued mankind for millenia. Aftercenturies of speculation as to the pos-sible infectious nature of tuberculosis,Koch proved conclusively that thecause of the disease was infection by aspecific micro-organism which he iso-lated. In tuberculosis, both seed andsoil play their part, but without theseed - the tubercle bacillus- there isno disease.On the occasion of the centenary of

Koch's discovery of the tubercle bacil-lus, we pay tribute to the father of themodern scientific approach to themanagement of tuberculosis.

LIFE OF ROBERT KOCH

Robert Koch, the son of a miningengineer, was born on 11 December1843, in Clausthal, a village in theHarz mountains. In 1862, he began hismedical studies at Gottingen Univer-sity, where he came under the influ-ence of Jacob Henle. In 1866 he quali-fied maxima cum laude with an MDthesis on succinic acid. For a time hewas in general practice in Rakwitz, but

in 1871, during the Franco-Prussianwar, he served with the German Army.On his discharge in 1872, he becamedistrict physician in Wollheim, and itwas here that his wife presented himwith a microscope on his birthday, andhe set up a primitive laboratory andbegan his study of infectious disease.In 1876, Koch demonstrated the lifecycle of the anthrax bacillus andshowed for the first time a specificmicro-organism to be the cause of adefinite disease. He was then invited toBreslau to continue his bacteriologicalresearches, and the next three years(1877-80) proved to be exciting andfruitful. In this time, Koch single-handed laid the foundations of mod-ern bacteriological technique -introducing glass slides and coverslips, examination by hanging drop,fixing and staining of bacteria, cultureon solid media by the poured-platemethod, micro-photography, and dis-infection by steam sterilisation. Usingthese techniques, he demonstratedstreptococci and staphylococci as the

Reprinted with the kind permission of Thorax (1982: 37: 246-251) and the author.

Can Vet J 1983; 24: 127-131. 127

common causes ofwound infection. In1880 he was appointed to the Kaiser-liche Gesundheitsamt (ImperialHealth Office) in Berlin (fig. 1).

In August 1881, Koch attended theSeventh 1nternational Medical Con-gress in London, where his demonstra-tion of his bacteriological techniquescreated a sensation. Even Pasteurexclaimed: "C'est un grand progres,Monsieur!" Tuberculosis was animportant subject considered at theCongress, and Koch returned to Berlindetermined to find the causative orga-nism. By March 1882 he had succeeded.

In 1883, Koch headed the Germancholera commission in Egypt andIndia, where he isolated the choleravibrio as the cause of the disease. By1885, he had been elected Professor ofBacteriology in Berlin, and the KochInstitute was built for him in 1891.There Koch attracted a host of excep-tionally gifted co-workers Gaffky,Eberth, Loffler, von Behring, Pfeiffer,Welch, Kitasato, Ehrlich, Wasser-mann, and others. He continued hisresearches into tuberculosis and 1890saw his controversial introduction oftuberculin. He was now travellingabroad a great deal, studying the trop-ical diseases of Africa and India. In1905, he was awarded the Nobel Prize

Robert Koch Memorial in RobertKoch Plaz, Berlin.

for Medicine, for his work ontuberculosis.Koch had married Emmy Fraats in

1867 and there was one daughter, butlater this marriage broke up and in1893 he married a young actress,Hedwig Freiburg. He died in Baden-Baden on 27 May 1910, aged 67 years.

TUBERCULOSIS BEFORE KOCH

Tuberculosis was a disease known tothe ancients and Hippocrates andGalen suspected its contagious nature.In 1650, Sylvius described the tuber-cle, and by 1819, Laennec was con-vinced that the tubercle was the com-mon factor in all forms of the disease,which was christened "tuberculosis"by Schonlein in 1839. Pasteur's germtheory of infectious disease (1862)provided a stimulus for the search forthe causative organisms of the variousinfectious diseases. In the field oftuberculosis, the first major break-through was by Jean-Antoine Vil-lemin (1827-1892), who in 1865showed by animal experiments thattuberculosis could be inoculated fromman or cow to rabbit or guinea-pig,and that the sputum of a consumptivecould infect a rabbit with tuberculosis.The British Government set up acommission to investigate these claimsand Sir John Burdon Sanderson andSir John Simon confirmed Villemin'sfindings.

In 1877, Cohnheim and Salamonsensuccessfully inoculated tuberculosisinto the anterior chamber of a rabbit'seye and Tappeiner was able to infectdogs with tuberculosis by exposingthem to inhalation of droplets ofinfected material. The question nowwas not whether tuberculosis wascaused by micro-organisms, but whowould be the first to demonstrate it. Itwas at this stage (1881-82) that Kochembarked on his search for the tuber-cle bacillus.

DISCOVERY OF THETUBERCLE BACILLUS, 1882

It was,on 24 March 1882 that Kochannounced the discovery of the tuber-cle bacillus. The occasion was themonthly evening meeting of the BerlinPhysiological Society. The reason whyKoch presented his paper to the Phy-siological Society and not to thePathological Society may have been

Rudolf Virchow, Professor of Pathol-ogy, who was the dominant figure inBerlin medicine at that time. The meet-ing started at 7 pm in the reading roomof the laboratories of Professor DuBois-Reymond, who took the Chair.Among the 36 members present thatevening were Helmholtz, Loffler,Ehrlich, and other famous medicalfigures. Koch entitled his addresssimply "Uber Tuberculose" and des-cribed his discovery:"With regard to tuberculosis, it wasto be expected that the discovery ofpathological organisms might beattended with unusual difficulty,since many attempts had been madeto demonstrate them without pro-ducing satisfactory results. I beganmy investigations, using material inwhich the infective organism wouldsurely be expected, as for example infresh growing grey tubercles fromthe lungs of animals which had diedthree to four weeks after infection.From such lungs, hardened in alco-hol, sections were prepared and forthe proof of the bacteria, the usualmethods were employed. Also greytubercles were crushed, spread oncover glass, dried and tested for thepresence of micro-organisms.Efforts to find other micro-organisms in these preparationswere unsuccessful."

The method Koch used to stain anddemonstrate the bacilli he describedthus:

"Earlier observations having shownthat in certain cases the deepeststaining and clearest differentiationof bacteria from surrounding tissueswere yielded by the use of stainswhich were of alkaline reaction,advantage was taken of this fact. Ofthe common aniline dyes, methylene-blue bears the freest addition ofalkalis, therefore this staining mate-rial was chosen; and to a waterysolution of it, caustic potash wasadded.... When the cover-glasseswere exposed to this staining fluidfor 24 hours, very fine rod-likeforms became apparent in thetubercular mass for the first time,having, as further observationsshowed, the power of multiplicationand of spore formation and hencebelonging to the same group oforganisms as the anthrax bacillus. It

because of his poor relationship with was incomparably more difficult to

recognise these bacilli in sectionsamong the heaped-up nuclei andmasses of detritus, and an attemptwas made to render the tuberclebacilli more evident by contrast-staining according to the method bywhich Weigert succeeded ... byusing a concentrated solution ofvesuvin. Microscopic examinationthen showed that only the pre-viously blue-stained cell nuclei anddetritus became brown, while thetubercle bacilli remained a beautifulblue."Originally Koch had used an old

preparation of methylene-blue, but onrepeating the experiment with a freshpreparation, the bacilli were notstained. It then occurred to Koch thatatmospheric ammonia had renderedthe methylene blue alkaline. It was forthis reason that Koch came to addcaustic potash to the methylene-blue.

Culture of the tubercle bacilliproved to be difficult. EventuallyKoch used the cattle-blood serumsolid medium devised by ProfessorJohn Tyndall, and by the tenth tofifteenth day, very tiny coloniesbecame visible through the magnifyinglens. Koch now searched every varietyof tuberculous material, both humanand animal, and was gratified to findtubercle bacilli in them. He also notedthat the same technique stained theleprosy bacillus, which had been iden-tified by Armauer Hansen in 1873.However, Koch's description of sporeswas erroneous - what he saw musthave been the small refractile bodies(bacillary segments or granules) de-scribed in 1907 by Much.

Loffler, who was present at the lec-ture, later described how Koch (thenaged 38 years) began speaking withsome diffidence, since this was hismaiden speech before such a distin-guished gathering. However, he wassoon in his stride and the account ofhis experiments and findings were de-livered in a cool and confidentmanner. When Koch finished, therewas no applause or discussion, but hisaudience must have sensed the privi-lege of having been present at a his-toric medical occasion.

WORLD REACTION TO THEDISCOVERY

Seventeen days later, on 10 April 1882,Koch published the lecture in the Ber-

liner Medicinische Wochenschrift,under the title "Die Aetiologie derTuberculose." The disease which hadravaged and mystified for so long hadnow, at long last, divulged its secret.The news soon spread, and apart fromaccounts in the medical journals, thediscovery hit the headlines of theworld national press.Koch had sent a copy of his paper to

Professor John Tyndall in London,who immediately published the essen-tial findings in the form of a letter toThe Times on Saturday 22 April 1882.The next day Sunday 23 April, theNew York World carried a report ofthe discovery, and this was copied thenext day, Monday 24 April, in thePhiladelphia Public Ledger. By 3May, Tyndall's letter to The Times wasreported in full in the New York Timesand New York Tribune, and it was alsofeatured in the New York Times onSunday 7 May. As the news spreadaround the world, Koch became,almost overnight, a household name,and "Koch's bacillus" and "Koch'sdisease" entered medical jargon.There were many (and these

included Virchow) who found it diffi-cult to accept that the bacillus whichKoch demonstrated was the cause, andnot merely an accompaniment, of thedisease. Gradually, however, even themost dubious and sceptical were con-verted to the new knowledge.As with most major scientific dis-

coveries, there were rival claims forpriority of the discovery of the tuberclebacillus. Baumgarten and Aufrechthad perhaps seen the bacillus in tuber-culous material around the same timeas Koch, but they were unable to stainand demonstrate it as Koch had done.As Rene and Jean Dubos have written:"ln science the credit goes to the manwho convinces the world, not to theman to whom the idea first occurs."'

STAINING OF THETUBERCLE BACILLUS

The great Paul Ehrlich (1854-1915),then assistant to Professor von Frerichat the Charite Hospital, Berlin, hadbeen present at Koch's lecture on 24March 1882. Ehrlich was then aged 28years. He subsequently wrote: "Theevening stands in my memory as mygreatest scientific experience." Duringthe lecture, Ehrlich recalled seeing, invarious materials including sputum,

bacilli similar to those demonstratedby Koch. Immediately the lecture wasover, he obtained from Koch a pureculture of tubercle bacilli and thatsame evening he hastened to his labor-atory at the Charite and experimentedwith various stains. Ehrlich hadalready devised a stain for mast cells,using aniline water, fuchsin andgentian-violet. He now experimentedwith these stains to demonstrate tub-ercle bacilli. He used a shorter stainingtime (15 to 30 minutes, instead ofKoch's 24 hours) and he also applied30% nitric acid and alcohol for a fewseconds in order to decolourise thesurrounding tissues, while the tuberclebacilli retained their stain. On counter-staining with a yellow or blue dye, thered tubercle bacilli showed up moreclearly than by Koch's method.

It was by accident that Ehrlichlearned of the benefit of heating theslide. In his laboratory there was asmall iron stove in which the fire hadbeen out for some hours that evening.Before returning home, he placed thestained preparations to dry on the topof the cold stove. The next morning hewas annoyed to find that the stove hadbeen lit, but when he examined theslides he was astonished to find thebacilli in clumps showing up evenmore clearly. Ehrlich hastened to tellKoch, who immediately realised thatEhrlich's staining method (using heatand decolourising with acid) wassuperior to his own. Shortly after-wards, in May 1882, Ehrlich publisheddetails of the technique. Later Ziehlintroduced carbolic instead of aniline,while Neelsen advocated the use ofsulphuric instead of nitric acid. In thisway, the "Ziehl-Neelsen" (ZN) stainand the "acid-alcohol fast bacillus"(AAFB) were born.Koch wrote later (1883):"It was soon found that withEhrlich's method of staining, therecognition of tubercle bacilli couldreadily be made use of in diagnosis.We owe it to this circumstance alonethat it has become a general customto search for the bacilli in the spu-tum, whereas without it, it is likelythat but few investigators wouldhave concerned themselves withtubercle bacilli."It is of interest that, in 1887, Ehrlich

tested his own sputum, in which hefound tubercle bacilli, diagnosed pul-

129

monary tuberculosis, and proceededto Egypt, where he stayed for twoyears and then returned cured.Koch had a dry sense of humour,

and when once asked how long it wasnecessary to flame a slide when stain-ing for the tubercle bacillus, he replied,with a twinkle in his eye: "As long as ittakes to say: 'Robert Koch is a greatman!' "

"DIE AETIOLOGIE DERTUBERCULOSE"

After publication of his first paper onthe tubercle bacillus in April 1882,Koch continued his researches intuberculosis. In 1884, he published amore comprehensive paper, "DieAetiologie der Tuberculose," in thesecond volume of Mittheilungen ausdem Kaiserliche Gesundheitsamt(Reports of the Imperial HealthOffice).

In his 1882 paper, Koch had omittedto give adequate credit to previousresearch workers and was especiallycriticised for his perfunctory referenceto the important experiments of Vil-lemin. This omission may well havehad nationalist and political under-tones. He did however make passingreference to the work of his own coun-trymen, Cohnheim, Salamonsen,Baumgarten, and Tappeiner. How-ever, in the fuller 1884 paper, Kochrectified this, and gave credit to all,including John Tyndall, and especiallyto Ehrlich for his staining technique,which superseded Koch's originalmethylene-blue method. It was in thisclassic paper, a masterpiece of medicalliterature, that Koch described his pos-tulates - the stringent criteria whichan organism must fulfil before it can beconsidered to be the cause of an infec-tious disease: (1) the organism must beisolated from the diseased tissues inevery case of the disease; (2) the orga-nism must be grown in pure culture;(3) inoculation of a susceptible animalwith the organism must reproduce thesame disease; (4) the organism must berecovered from the infected animaland be grown again in pure culture.

KOCH AND TUBERCULIN

Although Koch was involved laterwith many other bacteriological prob-lems, he continued to take a specialinterest in tuberculosis.

In 1890, the Tenth International

Medical Congress was held in Berlin,where Koch read a paper "On Bacteri-ological Investigation". It was on thisoccasion that he dropped a bombshellby announcing that he had a substancewhich hindered the growth of tuberclebacilli, cured tuberculosis in infectedguinea-pigs and would probably beuseful in the treatment of humanphthisis, especially in its early stages.

Later, in the autumn of 1890, Kochpublished a paper on the subject whichbegan:

"In a communication which I madea few months ago to the Interna-tional Medical Congress, I describeda substance of which the result is tomake laboratory animals insensitiveto inoculation of tubercle bacilli,and in the case of already infectedanimals, to bring the tuberculousprocess to a halt."What Koch described was known

later as the "Koch Phenomenon" -that is, resistance ofan infected animalto reinfection. Koch at first gave nodetails of the preparation or composi-tion of this substance, which he consi-dered had diagnostic as well as thera-peutic potential, and he emphasisedthat his researches were not yet con-cluded. The substance came to bereferred to as "Koch's Lymph." How-ever, so much pressure, both nationaland international, was brought to bearupon him that by January 1891, hepublished a further paper, whichdivulged that the substance was a fil-trate from a growth of tubercle bacillion glycerol broth. The name "Tuber-culin" had originally been voiced byPohl Pincus in 1884, but it was resur-rected by Bujwid in 1891, and Kochdecided to adopt the name. This is thesubstance which came to be known asOld Tuberculin (OT).The announcement of a cure for

tuberculosis, coming from a medicalscientist of such distinction as Koch,immediately excited interest through-out the world. A Lancet editorial wel-comed the news as "glad tidings ofgreat joy" and the British MedicalJournal was no less enthusiastic. Bothjournals published a complete transla-tion of Koch's paper. Koch'sannouncement produced a profoundsensation on the MediterraneanRiviera. The English Review ofReviews in its December 1890 issuedescribed how:

"The news that the German scientisthad discovered a cure for consump-tion must have sounded as the newsof the advent of Jesus of Nazareth ina Judean village. The whole com-munity was moved to meet him. Hisfame went throughout the region,and telegrams in the newspapersannounced that all the sleeping carshad been engaged for months toconvey the consumptives of theRiviera to the inclement latitude ofBerlin."The English physician and writer Sir

Arthur Conan Doyle travelled to Ber-lin to investigate the claims, and SirJoseph (later Lord) Lister took histuberculous niece to Berlin, so thatKoch could treat her himself. In theUnited States, 1000 dollars wereoffered for a teaspoon of the remedy.William Osler, then Professor at JohnsHopkins, Baltimore, had receivedfrom abroad two small bottles oftuberculin, and he generously sent oneto Trudeau for him to try out on hisconsumptives at Saranac Lake.With such international excitement,

the news that tuberculin was produc-ing severe reactions and, far frombeing a magic cure, was making manypatients worse, came as a dreadful let-down. High hopes were followed bysad disappointments, and Kochbecame the object of considerable crit-icism and even abuse. Koch defendedhimself by maintaining that he hadnever claimed tuberculin to be a uni-versal cure for all cases oftuberculosis.Koch nevertheless continued his

researches, trying to improve on hisoriginal tuberculin, and by 1907 heproduced what he considered to be abetter version, New Tuberculin, firstTuberculin Residue (TR) and laterBacillary Emulsion (BE), but whenthese were tested on patients they tooproved to be disappointing. Eventu-ally, Koch gave up completely the useof tuberculin as a cure. However,tuberculin was to prove to be of enor-mous value as a diagnostic tool to dis-tinguish the infected from the non-infected, especially when BCGvaccination was later introduced.Moreover, the study of the tuberculinreaction paved the way for subsequentresearch on allergy and immunity.

130

HUMAN VERSUS BOVINETUBERCLE BACILLUSCONTROVERSY

When Koch first described the tuber-cle bacillus in 1882, he considered thathuman and bovine bacilli were separ-ate organisms, confirming what hadalready been established by Villeminin 1865. However, in his 1884 paper,Koch concluded that the bacilli ofhuman and bovine disease were identi-cal; but, despite the fact that bovinetuberculosis was transmissible to man,he did not feel that such infection wasan important human hazard.

In 1898 Professor Theobald Smithof Harvard published his findings onhuman and bovine tubercle bacilli andclearly demonstrated them to be dif-ferent organisms. In 1901 the ThirdInternational Tuberculosis Congresswas held in London. Koch spoke atthis Congress and accepted the find-ings of Theobald Smith, but still main-tained that tuberculosis in cattle wasnot an important danger to man andspecial preventative measures wereunnecessary. This view provoked con-siderable opposition at the time. LordLister, who presided at the Meeting,opened the discussion and questionedKoch's views. When tackled later,Koch maintained that he had meantthat the bovine bacillus was only rela-tively less important than the humanvariety, which was responsible for thegreat majority of cases of infectiousphthisis.Considerable controversy ensued as

to what Koch had really said at theCongress. In 1903, the Privy Councilset up a Royal Commission on Tuber-culosis and its final report in 1911refuted Koch's alleged views, whichhad obviously underestimated theseriousness of bovine tuberculosis as apublic health hazard. The RoyalCommission recommended measureswhich were later put into effect by apolicy of eradication of infected cattleand the pasteurisation of milk. AGerman Commission came to thesame conclusions. Yet in 1908, at theWashington Congress on Tuberculo-sis, Koch still maintained that infec-tion of man by the bovine bacillus was

negligible and did not justify specialpreventative measures.

C O N C L U S O N

The science of bacteriology owes itsorigin to two men of genius, LouisPasteur and Robert Koch. As Webbhas written, Pasteur may be describedas master-architect and Koch asmaster-builder of the science. In thefield of tuberculosis, Koch's discoveryof the tubercle bacillus and tuberculinrevolutionised the management of thisdisease.On the occasion of the centenary of

the discovery of the tubercle bacillus,we salute Robert Koch whose contri-butions to bacteriology and tuberculo-sis place him among the medicalimmortals.

SELECTED BIBLIOGRAPHYAUFRECHT E. Die aetiologie der tuberculose.

Centralblattfur der Medicinischen Wissen-schaften 1882; no 17 (April 29).

BAUMGARTEN P. Tuberkelbakterien. Central-blattfur der MUedicinischen Wissenschaften1882; no 15 (April 15).

BROWN L. Robert Koch: an American tribute.Ann Med Hist 1935; 7: 93-112, 292-304,385-401.

BULLOCH w. The history of bacteriology, NewYork: Oxford University Press, 1938.

CUMMINS SL. Tuberculosis in history. London:Bailliere, Tindall and Cox, 1949.

DUBOS R, DUBOS J. The white plague: tuberculo-sis, man and society. London: Gollancz,1953.

FORD WW. The life and work of Robert Koch,Johns Hopkins Hospital Bulletin 1911; 22:415-25.

GAFFKY G. Robert Koch. Dtsch Med Wochenschr1910; 36: 2321-4.

KEERS RY. Pulmonary tuberculosis: a journeydown the centuries. London: Bailliere, Tin-dall, 1978.

KNOPF SA. Robert Koch: the father of the mod-ern science of tuberculosis. John HopkinsHospital Bulletin 1911; 22: 425-8.

LANDIS HRM.The reception of Koch's discoveryin the United States. Ann Med Hist 1932; 4:531-7.

MARQUARDT M. Paul Ehrlich. New York: Schu-man, 1951.

PALTAUF R. Robert Koch. Wien KlinWochenschr 1903; 16: 1377-81.

SAKULA A. Robert Koch: founder of the scienceof bacteriology and discoverer of the tuber-cle bacillus. Br J Dis Chest 1979; 73: 389-94.

SAKULA A. Baroness Burdett-Coutts' garden

party. International Medical Congress,London, 1881. Med Hist 1982; 26: 183-90.

SMITH T. Koch's views on the stability of speciesamong bacteria. Ann Med Hist 1932; 4:524-30.

Transactions of Third International Congresson Tuberculosis. London 1901; 1: 27.

WEBB GB. Robert Koch. Ann Med Hist 1932; 4:509-23.

WEZEL E. Robert Koch: eine biographische stu-die. Berlin: Hirschwald, 1912.

ZIEHL F. Zur farbung des tuberkelbacillus. DtschMed Wochenschr 1882; 8: 451-3.

A P P E N D XKOCH'S PUBLI CATIONSON TUBERCULOSIS

1882 Die aetiologie der tuberculose. BerlinerKlinische Wochenschrift 19; 221-30.

1883 Kritische besprechungen der gegen diebedeutung der tuberkelbazilien gerich-teten publicationen. Dtsch MedWochenschr 9; 137-41.

1884 Die aetiologie der tuberculose. Mitthei-lungen aus dem Kaiserlichen Gesund-heitsamt 2; 1-88.

1890 Weitere mittheilungen uber ein heilmit-tel gegen tuberculose. Dtsch MedWochenschr 16; 1029-32.

1891 Forsetzung der mittheilungen uber einheilmittel gegen tuberculose. Dtsch MedWochenschr 17; 101 -2.

1891 Weitere mittheilung uber das tuber-kulin. Dtsch Med Wochenschr 17;1189-92.

1897 Uber neue tuberkulin praparate. DischMed Wochenschr 23; 209-13.

1901 Die bekampfung der tuberculose unterberiicksichtung der erfarungen, welchebei der erfolreiden bekampfung andererinfektionskrankheiten gemacht sind.(Vortrag gehalten aufdem britische tuber-culose-congress). Disch MedWochenschr 27; 549-54.

1901 Uber die agglutination der tuberkelba-zillen und uber die verwerthung dieseragglutination. Dtsch Med Wochenschr27; 829-34.

1905 (With Schutz W, Neufeld F, MiessnerH.) U ber die immunisierung von rinderngegen tuberculose. Zeitschrift furHygiene und Infektionskrankheiten 51;300-27.

1906 Uber die rolle der milch bei der ubertra-gung der tuberculose auf menschen.Molkerei-Zeitung 16; 37.

1910 Epidemiologie der tuberculose. (Vor-trag gehalten in der sitzung der akade-mie der wissenschaft, zu Berlin am 7April 1910). Zeitschriftfur Hygiene undInfektionskrankheiten 67; 148.

131