&[AY 12, I9I71 THE COMMON INTESTINAL ENTAMOEflAE OF MAN. (M̂tTA.J oo it

should be used for this purpose. There is barley and maltuLsed for the production of alcolhol, an inefficient form offood at- the best and a deadly poison in excess. Accordingto tlle Food Controller thlere are one million quarters ofbrewer's mnalt in this country at tlle present time; it is notto be used for food, butt for tlle production of beer. Theconvictions for drunkenness in. the Metropolitan Police-District and tlle City for the first quarter of this year were6,176. The Food Controller says that the food value ofbeer is not disputed, alnd the Government does not con-sider that it is necessary to save the millions of quartersof barley, malt, and othler foodstuffs wlicll are to be usedin the manufacture of alcolholk There may be reasons ofpolicy for allowing alcolhol to meni in the services or em-ployed in some essential occupations, but tllere is nolne forits widespread consumption.

Oats can be used as a substitute for whleat, but there isclifficulty in obtainincg a ready and cleap supply; thle oatsare beingy kept for the lhorses. A lhorse may consume40 to 80 lb. of oats per week, and lhunters and racehorsesreceive the best. Huntingo, and racing lhave been and areallowved; only now is the Government taking steps to con-sider wlhetlher savings in this respect slhould be effected inthe interests, of the food supply of tlhe people. Tllere aretllousanids of lhunters, racelhorses, riding lhorses, anid car-riage-horses, used only for pleasure in this counitry; theconsumption of oats, niaize, beans, lhay, straw, and carrotsby these animals must be enormotus. Witlh the exceptionof the lhay and straw, whNbich would be useful for cows, allthese tons of food could be used by man himiiself; tlheobjection that thle horses are needed as a reserve for breed-ing and for the arnm lhas lno force, for all these animialscould be liept at grass, aid' under these conditions -wouldliberate many mienli for essential worlk.

TABLE II.-Perce t'aqfle Compositioni of Certain Cereals.

- tProtein: Fat. Carbo- Fuel V'aluieProtein. Fat. hydrate. per lb.

Calories.Wheat, flour 8.3 1.0 73.5 1615

Barley, pearled 6.6 1.0 76.1 1630

Maize, flour 5.8 1.2 76.3 1625

Oat, meal ... 13.4 6.6 65 2 1795

All of these substances lhave been used even in times ofpeace as substitutes for wlheat. In somc respects oats arei better food than -wheat and the fuel value of 1 lb. isgreater than tlle total for one day of the voluntary rationsuggested by the Food Controller. A lhorse eatinga daily10 lb. of oats consumes an amount of cereal food whlichwVould be sufficient for ten to twventy nen.Sugar and potatoes are foods whiclh were introduced

into this country in .ti'mes relatively recent, and it isobvious that they are not so essential as somne peopleiliagine. The 'cllildren should lhave the first claim onsugcar, and they could also obtain milk sugar in mnilk andmalt sugar in malt, besides those essential substancesknown as "1 vitamines."The supply of milk is anotlher difficulty, and it lhas

received the attention of the Governmeut. A muaximumprice has been fixed for the retailer and the producer; thefarmers lhave been selling their cows and givingc, up theproduction of milk, notwithstanding the fact tlhat it wasa very lucrative business according to maniy writers to thedaily press. For young clhildren, invalids, and our siclk andwounded soldiers milk is a food for wlhich, no efficientsubstitute can be found. In the case of infants tllepractice of wet nurses slhould be revived if tlle mDotliercannot or will not suckle lher clhild.During the spring and summer miiontlhs there may be

no serious shortage, for those are tlle best montlhs; whlenthle cows are at grass the supply is large anld feeding isclheap. Th-ere is a shortage at.the present timne, ancl theautuinn and winter will slhow tlle effects of tlle reductionof tlle milking lherds. Action, lhowever, mnust be takennow.10 Heifers caninot be made into milel cowvs uniider telnmonlths. Thle Goverinmlent hlave revised thleir "'milkorders "; thle farmers ask for thle recall of thlene orders.In any case a reserve of cows3 couldl be provided by thle endof nlext wrinter if thle Govreinlment p)urchlased at oncenumerous hleifers and turnedl thlem out to graze with

y9ung bulls on land owned or taken over by the Govern.ment. Even if money were an object, the transactionwould be probably a very profitable one. A supply of milkshould be safeguarded, and its cost should be low for thesake of the children, even if it be necessary for the Stateto give a subsidy.

If the scarcity of food is general, the true remedy lies inan extension of the supply. Action has been taken at last,pasture lhas been plouglhed up, but thle higlhly fertile groundof tlle lhop gardens will apparently in many cases stillgrow liops for beer, instead of corn or potatoes for bread.Tlle lhop growers slhould have compensation, if necessary,but food they slhould grow, for it is food whichl is needed.Another source of food whlell is undeveloped is tlle salt-

water and the fresh-water fish, but this, owing to the supplyof cattle, is not so urgent as the question of cereals.

If tlhe cost of food continues to rise, difficulties of aserious kIind must occur,' for a strong mian is liable tobecom-le dangerous wlhen lie is lhungry. A correspondingrisc in wages does not meet every difficultv. The wage isnot adcjusted to the size of tlle breadwinnler's family. Agreat relief and a true safeguard fbr the present aind tlhefLuture wouLld be the free supply of dinner and tea to scllool-clhildren; the necessary miaclhinery is sillmple, if the expenseis a general one borne by the State. Tlle lhealtlh of thefuture generation could be secured, a great burden wouldbe taken from many lhard-workino and deservintg parents.Foodstuffs -which tlle labouring classes cannot obtainreadily or cook properly could be used in these free mealsand bread would be saved. There would be no danger tllatthe children would be overfed, for evein with active andgrowing clhildren the law of averaaes as regards food'would lhold good. Many children, as well as men andwomIlell, are doing more work thani they ever did before;this means an increase in the coinsumlption of food,especially cheap food, such as the cereals.

Petty orders, suclh as the prohibition of Sunday-schooltreats and cakes, slhow nao appreciationi of tlle laws ofnutrition, and cause an amnount of irritation out of all pro-portion to tlle resuilt obtainied. The owner of poultry is notallowed corn for hiis fowl; the lhen does not return in eggsand flesl the food value of the grain consumed; no animalever did or ever will, for it must lhave some for its life.When allowance, lhowever, is made for the consumption ofrefuse the llien is economnical. The owner of racelhorses,lhunters, and otlher horses used for pleasure, is allowed inunlimited quantities tlle very best oats, maize, and beansthat lie can buy. He takes the food from tlle moutlhs ofthle poor by outbidding them in tlle purchlase of some oftlie- best articles of food wlliclh are scarce at tlle presenttimle.

ON THE THREE COMMONIAO INTESTINALENTAM-IOEBAE OF IMAN, AND THEIR

DIFtFERENTIAL DIA-GNOSIS.BY

CLIFFORD DOBELL, M.A.,IMPERIAL COLLEGE OF SCIENCE,

AND

MARGARET W. JEPPS,BATHU1RST STUDENT, NEWNHAM COLLEGE, CAMBRIDGE.

(Rep)ort to the MAedical Be8earch Committee.)

AT the present day the belief is wide&y lheld thatthere are only two amnoebic parasites of the hlumanintestine-thie harmless Entamoeba coli, and the dysen-tery amoeba, E. histolytica. Although it is certaintiathnearly all the amnoebae hiitlherto des.oribed fromnlhumani faeces actually belong to one or othe\r of these-species, whlatever lnames may lhave been bestowed uponthem, nevertlheless it is now possible to say with equalcertainty, we believe, that there are not two, but in realitythree different Entam)ioebae coimlmonlv inlhabiting tllehuman bowel. Our own observations hlave convinced uspersonally of this fact, anid in conjunction witlh those ofotlherg recentlv published hlave, we believe, placed tllematter beyond all doubt. As nlany people are nowengaged in the diagnosis of amoebic infections, and asthley are still in many cases-as -we lhave good reason tobelieve-confining their attention to certain forms of thetwo well-known species only, we think no excuse is needed-,

6o M-IAJU~A H O M N I T SIN L E T M E A F M N M Y1,11

for offering tlle following summary of ouir presgnt know-ledge of this matter. It is clearly of conisiderable inm-portanice tllat the facts slhotuld be widely lin)nwn, as thereare still many convalescent dysenteric patients in themiiilitary lhospitals and de6p6ts in this coantry wlho aiebeing examined anid treated for infection witlh Eintamctoebahistolytica. A correct diagnosis of suell infections is notpossible unless the tlhree species of Entamtoeba comnmonilyoccurring in- stuchl patients are clearly differentiated fromone anotlher, atid fronm otlher organiismis.We may begin by briefly recording,, our own experiences,

indicating later hlow they agree witlh, or differ from, tlloseof otlhers.

Not so very long ago it was generally suipposed tlat thecysts of Enttamnocba histolyticat ciuld be readily distin-guislhed from tliose of otlher Elatmoebae by tbeir size.It was-and still is-stated tllat thje cysts of this oraanismhave an average diamneter of about 12,u, individual cystsvaryinig frorn tllis mean by only onie or two microns as arule. We lhave long known that tlhis is not correct, anidthat there is a far greater rangae of szz observable in cystspassed in the faeces of differenit perscns. A case observedby onie of us at the beginnina of 1916 regularly passed,cysts of BE. histolytica having' an avt rrIe diameter ofonly 7 to 8p. Sinice then wve lhave observed imiany similarcases. In exaMningll tIhe stools of paticiets for thlese sm-allcysts -we frequjenitly enicounte-red othier smiall cysts con-taininig one, two, or four luiclei, but dlifferinia in structuIrefrom those of E. 7histolytica, wllicll at times gave us coln-siderable trouble in diagnosis. Tlhese' eysts lhad beenfigured by Wenyon (1915), and attsKbated bv himl toChilomastix (- "'Tetramitts-"). mes-nili That they didnot belong to this organismii we, sooni convineed ourselves,as we have-lon-g been famiiiliar withi its very ciharacteristic,and -always uninueleate, cysts. But; to wliat organismnthiev really beloigled we were long unable to dIecide.Meanwhile we discovered oni niaiiy oc'3asions smiiall deador de(generate organisms, associate(I at timiies witih thlecvsts in question, anid otlher ' cysts " or ' bodies " clharac-terized by the pr-esence wvithjin thlemii of a large mass ofglycogen. We furthier discovered a smiiall amloeba wlhlichin somiie ways resembled tlle small free-living amnoebae ofthe Amioeba limiax type, but wlliclh, however, appeared tobe a true intestinal parasite, and not a coprozoic form, asit invariably died very quickly after leaving the body ofits host. We havo noNv been able to prove that all thesecysts and organisms are stagcs in tlhe life-hiistory of tllesame form-a small parasitic amioeba wlliclh is by no m-neansuncommon in the class of cases examined by us.In the meantime, descriptions of thlis organisnm lhave been

publislhed by Swvelenarebel anid Wiuoto (February. 1917)and by Wenyon anld O'Connor (Marchl, 1917). To thledescriptions and figures of the latter au-tlhors we can addbut little. They lave called the new organismnEntamoebanana, and lhave noted that it is a co:ulparatively commionparasite in Egypt. Its frequent occurrence in dysentericand otiler patients-in thlis-country lhas nob, we believe, beenhitlherto inote(d.We propose o4ow to describe very bi iefly our observations

on E. nana aind its cysts; to describe then the clhiefpoints of difference between these and those of E. histo-lyticcr-withl especial reference to smiiall cysts of the latter;to discuss very briefly certaini relevant details conieerninaE. coli; and to add a few notes oni the metlhods wlhiell welhave found most useful in identifying tlsese species. auddistinguishlinlg thenii from otlher organisms, in tlhe routinoexamnination of human faeces for tlle detection of protozoalinfections.

Entamzoeba nana (Wenyon and O'Connor).E. nanta is a very snmall amoeba mneasuLring, when

rounded, about 6 to 12 L in diameter, tlle majority of in-dividuals being about 8 . In general structure it soie-wh1at resembles maniy amoebae of tlle so-called limax group.Trhe protoplasin is generally muclh vacuolated, the vacuolesicontaining bacteria upon whlich the animal feecds. Tlhereis no contractile vacuole. Tie pseudopodia are few, blunt, |and hyaline. The very characteristic inuleus is ratlhersmall, and niot always easfly observable in the living"organisms. Its lkaryosonie is smaller tlhani tllat in thenucleus of a typical A. Illmax, and usually occuLpies anapparently excenitric or periplheral position. It is ustuallyirregular in shape and oftenl segmlenlted inito several piecesof unequal size united by slender tlhreacds. (See Fig. 2.)

Tlle amoeba mnoves very sluggishly on a cold stage, andvery soon becomiies rounded up and dies. Attempts atcultivation on aimoeba agar have' always failed.The cysts are oval or splherical structures, usually

measutring 8 to 10%u in lengtll or 7 to 8 ,u in diameter. Tllenuclei are 1, 2, or 4 in numnber in the vast majority ofcysts, closely resemiibling in structure those of tlle unen-cysted amnoebae, except for tlleir smaller size in late staaesof development. (See Figs. 7, 8, 9.) In the quadrinucleatecyst the nluelei usually lie near to one anotlher, andfrequently in close contact. Very rarely cysts lhave beenobserved containing as many as eiglt nuclei.

In addition to thie nuclei the cysts containi a variablenumiaber of highly refringent granules wlliclh give somne ofthe reactions of volutini; and sometimes-especially in tllebinucleate stage-a large dull incltusion is also visible inthe living cyst. This is comiiposed of a substance insolublein alcolhol, soluble in water, colournd dark brown by iodine,and- brighlt red witlh Best's carmine, fromn wllicll we con-cltude that it. is a miiass of glycogen.The cysts of E. nana appear to be very resistant.

Although they canniiot wvitlhstand drying, they remiiainapparently unchanged in nmoist faeces for more than tlhreeweeks. We lhavd stained specim-lenis imade aftee' an intervalof twenty-four days wlichl are as good as those made fromthe freslh stool.

Frolml tthe fact that personis infected witlh E. nania somc-timiies pass diarhlloeic stools which containi only cysts, itseems to us not improbable that the lhabitat of tllis amiioebais tlle small intestine. (A similar plhenomenon is seen inthe case of Lamblia whlliclh inlhabits thle smiall intestine, butis very unusual witlh the protozoal parasites of tlho colon.)We lhave no evidenice to slhow that E. ntana is patlhogenic.

Tle majority of infections studied by us- were in conl-valescent dyseniteric cases; but we lhave n'o reason tocorr.elate tlhe infection witlh the dysentery, and lhave founldtlle amiioebac in l)ei'sols witlh n1o dysenteric history. AXs tlleorganism'i resembles F. coli in its food lhabits, it seeimisilkely that it is e(qtually hlarmiiless. Anany of our cases havebeen treated for EJ histolytica infection witlh em-ietinlebisniutlhous iodide, but in nio case lave we-observed thatthe treatmenit remiioved the E. nantla. In tllis respect also,tlherefore, tllis organiism resembles tlle lharmuless E. coli,and differs from E. histolytica.

B. nana is in our experienice a very common parasite.It is only-recently that we lhave kept a careful record ofinfected cases, aud wve lhave not always determinied smallinfections and those in whliell -we found only dead anddegenerate orgauisms. Mloreover, most of our rceent caseslave been examiilned onlv tvice eachl, which we linow isinsufficient to detect all inifections. Nevertheless we lhaverecorded over 15 per cent. of the last four or five lhundredcases examined as infected wit1a BE. nana (73 infections iu478 cases).

It seems clear tlhat tihe orgaaiisn just dcsesibed isidentical witlh that desctibed by Wenyon and O'Connor,altlhough they do not nmentioln the occurrence of glycogeiin the eysts-a feature wlhiell we find very constant audcliaracteristic. Such cysts have, hlowevei-, been described'-by Swellengrebel and Winoto for their so-called " Amoebaliimax," wlliclh, as already noted, we a's) believe to beidentical witlh the amioeba studied by us. Wemiyon andO'Connor state (1917; that the organisms proviouslydescribed by AVenyon (1916) as A)mioeba Himax were inreality E. natia; but a still ear lier reference to thisorganism appear.s to us to be contained in a paper byJamues (1915). The description and figures of bis "free-living amoebae fromi tlle lhuman intestinal tract " seem tous to refer almost certainly to E. nana, althouhli lhe notedtlle occurrence of utlinucleate cvsts only. Jamiies hiinmselfidentified hiis organisms witlh thiose previously describedby Wenyon (1913) and Clhatton and Lalung-Bonnaire(1912). Wenyon's anaoebae may possibly lhave beenBf. nana,* buLt tlhose dlescribed by the Frenclh autlhors arecertainly not, as they are undoubtedly typical amiioebae ofthe limax group.

E. nana appears to lhave a wide geograplhical distribu-tioin. The infections -we lhave studied were in soldiersinvalideed to Encglanid f -om Egypt, Gallipoli, Salonica,*Colonel Weny on's returnl to Enigland since these lines were written

lhas enabled uis to detcrmiiine this point. He las -ery Iiinidly allowedluis to excamLine lpreparations of the amnoebae, wlhich lho first (]oscribedin 1912 (Joursro. London Schloolof L'rop. ited._ vol. ii, 1). 31). fie agreeswith us that the amoebae atre E. vanoa anxd thiis appears, therefore, tobe the first case of infection wvith this orgauism on record.

608 THP, 13n!n8H IMEDICAL JOURNAL j THE COMMON INTESTINAL ENTA-VOEBAE OF V.-,AN. [MAY 12, 1917

'MAY I2, 19I71 THE COMMON INTESTINAL ENTAMOEBAE OF MAI;.t- _ __

I

:'UCr

DESCRP!ITION Or, FIGJUP.]}:S.All filnrcs, 6xcept 13 and 14, depict fixec specim'lens stained with

ironll laematoxylin.FIG. 1-E. 7histolytica, amoeba of " nin0ta " formu belonging to

race formiiing smiiall cysts.FIG. 2.-E. nana, two free amiioebae: slhowing nuclei and

numerotus Vacuoles containing ingested bacteria.FIG. 3.-Amoeba of the A. limaz( group fromii hbtuman faeces somiie

days oid. Note the contractile vactiole, nucleus, and foodvacuoles.FiGs. 4, 5, 6.-Itnin'ucleate, binucleate, and quadrinucleate cysts

- Tes)ecttvely-of E. histolvtsca, aace producing small cysts. Theblack masses in the cysts are tbV deeply-stained chromatoid

Mesopotamia, France, and Soutlh Africa. Tlle casesstudied by -Wenyon and O'Connor were in Egypt, Janses'scases were in Panama, and the tlhree cases of S-wellengrebeland Winoto were a European in Sumatra, a Javanese inHolland, and a European from the Dutell Indies. It isnot, hlowever, possible to state that all the infections werecontracted in tlle places mentioned.We have followed Wenyon and O'Connor in placing tlle

amoeba just described in the genus Entamoeba. It differs,hlowever, so considerably from other members of the genus-especially in its nuclear structure-tllat we have doneso with some hesitation. We clo not yet tlhink it possibleto define the limits of the genus Enttamoeba with precision,owing to our ignorance of tlle complete life-hiistory ofmost parasitic arnoebae.

Entamnoeba histolytica (Scliaudiunn emend.).Thlis organisin is now so well known that it is unneces-

sary to redescribe it. We propose lhere merely to enter intosome detail concerning tlle dimensions of its cysts. Fora considerable time we lhave kept records of the size of thecysts in all infections wlhich we htave studied, and hiavetlhus collected particulars of 200 cases. We will nowsummarize tlhese as briefly as possible.In 75 of tlle infections cysts below 10 M in., diamiieter

occurred; and in 62 of these no cysts la.rger than 10,uwere ever found. In the remainder (13 infections) thesize of the cysts ranaed botlh above and below tllisdiameter. A few cases showed a variation in size from

bodies; the clear slaces in Figs. 4 and 5 the vacuoles, fromii wliclthe glycogen has been ex\tracted in miaking the preparations.FIGS. 7, 8, 9.-Uninucleate, binicleate, and quadrinucleate cysts

respectively of E. cnana. Comp11)are Figs. 4, 5, 6.FIG. 10.-CYst of typical 3Anoeba linmax, slhowving ntcleus,

chromatoid miiasses, and thick corrugated cyst wall.FIGs. 11 and 12.-Cysts of C07iloenastix iesnili, oval atnd 0ypicallemlon-shapeAd formn,s res)ectively; shoowing nucleus, remains of

huccal structures, and volutin grains.FIG. 13.-Binucleate dyst of E.anas,a in iodine solution. The

black mass represents the deeply-stained glycogeni vacpiole.FIG. 14.-Cyst of Ch. nssnsili containing large mass of glycogen,

as it appears in iodine solution.

7 to 15 . In all these infections cyst s nieasurinu7 to 9 , ivere by far the commonest.

In 127 infections, on- the otlher hand, only cysts above10 / iin diameter were seen. The diameter of the cvsts in123 of these varied from 10 u to not mnore thlan 15 j, tilemajority of cysts iangiua rouLnd 12 ,u. In the four remain-ing infections cysts as large as _6 L6.5 u and 17.6 wwererecorded. (In other cases wve hiave also observed cy'ts-undoubtedly of E. histolptica-which- attained a dia eteras great as 20, These diameters in all cases refer tospherical-not oval-cysts mneasured in saline' or iodinesolution.)

It will be noted that 'we hiave referred to 200 cases and202 infectiolns. Tllis i;s because two of tlse cases appearedeach to lhave two separate infections; eaclh passing cystsmeasuring either 7 to 8 IL or 12 to 14p, witlh none of inter-uediate size.We see no reason to dotubt tllat all tllese cysts belona to

E. h7islolytica, and represent simplv those formed bydifferent strains or races of a sinigle speeies. The occur-rence of nunmerous strains, differing -from onie anotlser insize alone, has been observed witllin almost all species ofprotozoa lIitlherto- subjected to systematic study. More-over, we have no reason to believe that tilese strains ofE. hsistolytica differ from. one anotlher in pathogenicity orany otlher clharacter save size; We may also note that allstrains behave in a precisely similar manner towardstreatmlent witlh emetine, given eitlher hvpodermicallv or asthe double (bismuthous) iodide per os.

Tux Da -60q-rM-ZDTCA,L JOVBNAL

I

'. I .,.

IF. I

'.' -4

THE COMMON INTESTINAL ENTAMOEBAE OF MAN. [MAY 12, I917

Although we suppose that those cases which pass cystsof two different sizes, with no intermediates, representinstances of simultaneous infection with two differentstrains, we are of course unable to determine whethercases passing cysts of all sizes from 7 ,u to 15 representmultiple infections, or infections with strains of amoebaewhich form cysts of varying size; since it is clear thateitlher interpretation 'ls equally possible.We have detected carriers of small cysts of E. hi8tolytica

among men coming from France, Egypt, Gallipoli, Salonica,Mesopotamia, and India, so that tlle stiains producingsmall cysts do not seem to be confined to any pariticularlocality.

Tlle pre-cystic amnoebae (" minuta" forms) sometimesfound associated with the small cysts differ only in theirsmaller size from those commonly met with in the largerstrains. When rounded they rarely exceed 10 IA in diameter.But whether the tissue-invading (" histolytica ") forms arelikewise smaller we are unable to say, since we have notbeen able to study the acute condition in any of ourcarriers of small cysts.We may perhaps observe that the name "Entamoeba

mninuta" is not properly applied to the strains ofE. histolytica forming small cysts. There can no longerbe any doubt that the organism described as E. miniutaby Elmassian (1909) was the ordinary strain of E. histo-lytica forming cysts of the laYger size. The small amoebaewhich he found associated with tllese cysts were merelythe small pre-cystic forms characteristic of subacute in-fections. Woodcock and Penfold (1916), and otlhers, aretherefore in error when they apply the name E. minuta tothe strain producing small cysts.

Small cysts of A. hi8tolytica appear to have been firstnoted by James (1915) in Panama. -Since then tlley havebeen found by Woodcock and Penfold (1916). They lhaverecently been carefully studied bv Wenyon and O'Connor(1917) in Egypt, with wlhose conclusions regarding themwe are in complete agreement. Matlhis and Mercier (1917),in discussing the size of the cysts of E. histolytica, lhaverecently stated that tlle usual dimensions are 12.5,u or 14 V.They cite no instances of cysts measuring less than 8.5por more than 15 p. We ourselves lhave seen cysts of allsizes from 5 pu to- 20 IA, in freslh preparations. And webelieve tlhat the Frenclh observers, if they would study thecysts from a large number of cases ratlher than a largenumber of cysts from a few cases, would reach conclusionsidentical with those of Wenyon and O'Connor and our-selves. We think it probable that Kuenen and Swellen-grebel (1913) and numerous other authors- wlho have foundthe majority of cysts of E. histolytica to measure 11 to 14 ain diameter have overlooked all infections witlh the racesproducing only small cysts (10 ,u or less). Others haverecorded these infections as rarities-for example, Wood-cock and Penfold (1916), and Smitlh and Matthews (1917).Nevertheless, since in no less than 62-that is, over 30 percent.-of the last 202 E. histolytica infections which wehave studied no cysts larger than 10,u were ever found, itappears that such infections are far from uncommon. Theimportance of tllis from a practical point of view need notbe furtlher emplhasized.- It should be added that the 200 cases of E. histolyticainfection referred to above were made up as follows:155 carriers detected at a dysentery dep6t; 21 carriersdescribed in a former paper by one of us (C. D., 1916),fromn a gen3ral military lhospital; and 24 carriers studiedat another military hospital by the other (M. W. J.), andabout to be described in a forthcoming article. Fourteenof tlle cases in the last two categories have no history ofdysentery.We give figures of the small pre-cystic amoeba (Fig. 1)

and of tlle small cysts (Figs. 4, 5, and 6) of E. histolyticafor comparison withl the corresponding forms of E. nana(Figs. 2 and 7-9).

Enztamizoeba coli (L6scb) Schaudinn.Concerning this faimiliar organism we here propose to

make only a few observations, chiefly on the size of thecysts and the number of their nuclei.

It is usually supposed that cysts of E. coli can be dis-tinguished from those of E. histolytica by their largersize. Most authors have regarded 15 ,u as the minimumdiameter of E. colt cysts. Kuenen and Swellengrebel(1913) -have recorded cysts measuring as little as 13,u,

however, and other authors have given even smallermeasurements. Quite 'recently Wenyon and O'Connot(1917) state that they have seen no cysts less than"thirteen or fourteen microns" which they could attri-bute with certainty to this organism. Mathis and Mercier(1917) place their lower limit of size between 12 p and13 p. We ourselves have, however, on several occasionsmeasured undoubted E. coli cysts as small as llp. Aswe have already seen, the cysts of B. histolyticaare frequently of this size and sometimes very muchlarger. It is therefore clearly impossible to use thesize of the cyst as a crucial character for the differ-entiation of these two species. We consider the onlycertain means of distinguishing the cysts of the twoamoebae from one another is the study of the structureand number of the nuclei. Although we have studied avery large number of cysts of both species we have neverfound those of E. histolytica containing more than fournuclei; 'and consequently we regard the' occurrence ofcysts containing more than four nuclei of the coli-histollytica type as the most certain criterion of an E. coliinfection. In this we agree 'entirely with Mathis andMercier, and differ from Swellengrebel and Schiess (1917).From time to time we have, like other observers, en-

countered E. coli cysts of very large size. These containas a rule, more than the eight nuclei of the typicalfully developed cyst. We have counted various numbersof nuclei up to sixteen, and in one cyst at least eighteen,and probably more, were present. The largest sphericalcyst that we have found measured 33.5 p in diameter,thouglh the long diameter of oval cysts has s'ometimesslightly exceeded this value.These figures approximate closely to those given by

Wenyon and O'Connor (1917), whose maximum measure-ments are 32 and 38A X 34 u.

Mathis and Mercier (1917) regard the large cysts ofE. coli containing sixteen nuclei as normal stages in thelife-history. For our part, lhowever, we think, it mostprobable that they merely represent double cysts formedfrom an originally binucleate amoeba. Such amoebae,whichl presumnably have been arrested in division, aresometimes found in stools. WeJ would remark that ifsimilar double cysts are ever formed by E. histolytica, todistinguish them from' the 8-nucleate cysts of E. coltwould probably be extremely difficult, if not impossible.

DIAGNOSIS.So much has already been written about tlle differential

diagnosis of E. coli and E. hi8tolytica that we slhallconfine ourselves, after a few general remarks, to a con-sideration of certain less discussed difficulties wlicll havearisen since the discovery of E. nana and of the smallcysts of E. hi8tolytica.

Concerning the unencysted forms of E. coli and E. histo-lytica we shall say but little. These have beeli discussed-so exhaustively by Wenyon and O'Connor (1917), and ourexperience is in all points of importance so entirely inagreement with theiis, that we have notlhing to add totlleir conclusions. We will merely emphasize once morethe fact that, in the absence of encysted forms, the specificdiagnosis of an entamoebic infection is frequently verydifficult, and not seldom impossible.- From the encystedforms, however, a correct diagnosis can usually be madewith certainty by a practised observer.The main differences betveen typical E. coli cysts and,

the larger-sized cysts of E. htistoly ica are now sufficientlywell known for a detailed description to be unnecessaryhere. As already noted, the size of the cysts is a characteron which too much reliance should not be placed. Anotherclharacter sometimes regarded as distinctive of E. -histo-lytica is tlhe presence of the'so- called "chromidial" or"crystalloid " bodies in the cysts. These bodies, whibhwe slhall call chromatoid bodies (since in our opinion they.have nothing to do with the chromidium of other rhizopodsand are not crystalloid), are, it is true, very generally-though by no means invariably-present in E. histolyticacysts but on the other hand we find they are by no meansuncommon, in the cysts of 'E. coli, as several authors havealready noted. We do not understand why Mathis andMercier (1917) deny their occurrence in E. coli cysts. Amuch more distinctive clharacter is the vacuole, which,however, is not usually present in fully mature cysts ofeither species. It is formed in the early stages of encysta-

610IO MDICAL JOUBRNAL J

AI

THE COMMON INTESTINAL ENTAMOEflAE OR MAN.

tlon and persists as a rule in E. histolytica until the4-nucleate stage is reached. In E. coli it is seen up to the4-nuceleate stage, but is very uncomnmon in cysts containing8 ntuclei. It attains *its maximiium size in E. coli durinigthe binucleate stage, whlen it frequiently occupies thegreater part of the cyst. SuLelh cysts we-contrary toW0enyoln and O'Connior-regarcd as niormnal stages in de-

velopnment. Unlike those of E. coli, E. histolytica cystsoften possess more than one vacuiole. Tlle vacuoles arebest studied in cystsmounited in iodine solution. As thoseof -E.. coli contain abunidant glycogeln, they stain darkbrown; wlhereas E. histolytica vacuoles, wlliclh containbtut little of this substance, are far less dleeply coloured.-In iodine solution the edge! of thle vacuole is ill-defined in-E. histolytica, but usually clear cut in E. coli. Theseclharacters are not absolutely constanit: we lave, for-instance, seen cysts of E. histolytica with vacuoles quiteas darkly stained and slharply outliued as those ofE. coli.That the substance in these vacuoles is really glycogen

there can lhardly be any doubt. I1n additioni to the iodinereaction above noted, we find( that it gives cllaracteristicreactions witl Best's specific carmine staini for glcvogeni,and displays the usual solubilities of this substance.As already noted, we regar(d thce number and structure

of the nuclei as thc most reliable clharacters for dis-tinguisliing cysts of E. coli fromu those of E. histolyitica.Some observers attacll considerable imiiportance to thetlhickness of the cyst wall-for example. I(uciiene an:dSwellengrebel (1913), Woodcock and Penfold .(1916)-acharacter whicli we, with Mathis and Mercier (1917),regard as qu'ite unreliable. Tile assertion that the cystwall of -E. histolylica lhas butt "a sinigle contour," -whileth1at of E. coii is double, appears to us to rest uponmalobservation or ani e-ror in micrt°oscopy.When we come to conisiderB. histolytic(a cysts of 10,u or

less in diamieter we can rule out E. coli as a possible soutrceof conftusion, but we encoulnter several new difficulties. It-should be borne in miiind thlat thje small cysts (lO,u or less)-of histolytica differ froin tile larger in nio respect save-size, so that anybody fam-iliar withi the latter slhould lhavelittle trouble in identifying tlle fornmer. T1'he chief addi-tional difficulty arises from the circunmstance that the-smaller the cysts are thle more troublesormle they are tofind, especially when present in the faeces in smallnumbers and accormpanied by other cysts and organismsof comnparable size and similar appea-ance. Tlhe ellief-cysts liklely to leadl to co'nfusion are those of E. nana andChitonzas8ix. The former are readily distinguislhed fLonmthose of E. histvlytica by thle structure of their nuclei, theabsenq of clhrmatoid bodies, and tlle clharacter of theglycogen vacuoles. Moreover, altlhouglh great variation isobservable in the -shape of the cysts of bothl species, tlloseof R. nana are generally oval, wvile those of F. histolyticaare typically spherical. Thc nuclei of sm-all E. ihistolyticaicysts are seldom distinctlv visible whlen tlle cysts are

examined in saline solution; while thlose of E. nCas-ia cysts

are, for all practical purposes, comlpletely invisible in thismedium. In iodine solutionl tlle uclei of E. histolyticacysts can generally be clearly nmade ont, wlhile this isseldom the case with cysts of E. name on account of thenumerous minute graniules (? volutin) whjiclh are generallypresent. As a rule tle clhrom-atoid bodies of E. histolytica.cysts are readily seen in saline or iodinie (especially in theformer), and when Wesent serve at onlce to distinguishthemn. The glycogen vacuoles, as al-eady nioted,shotuld be stuidied in iodine soluition, in whliclh tllesmall, faintly stained, and ill-defined vacuole ofE. hi8tolytica is easily distinguished f reoi the rela-tively large, deeplv stainied, and slia-ply definedglycogen mass of E. ntana (see Fig. 13). AWlThen the deter-winiation of the species still renlains in doubt thic onlv safeprocedure is to fix anid stain wet cover-glass preparations,and examinie theimi systematically witlh the oil ilellmc-sionD.Thle cysts are easily fixed anid stained by any good cyto-logical mncthod; but by far the most useful and rapidmiietlhod for routinie purposes is, in our experience, fixationwitlh Schaudiin's fluid, followved by staining in lhaemilaluLim..Otther rapid methodsl of stainina whichl lave given us good

esults are Weigert's iron-baemiatoxylin, carmxialumii, anldparacarmine. 'Though the best preparations al-e obtainiedlwitlh Heidenlhain's iron-ihaeiniatoxylini stain, it is quiteunnecessary to use tlis laborious and leigthly metlod formere diagnosis.

As noted above, the ysts of E. hzisto-lytica miiay also beconfused with those of Ghioinastix (-- Tet-ramituls), whlicllare frequently present in hluman faeces. As publislhedaccounts of tllese ai-e remarkably divergernt, and in somneocases incorrect., a redescriptionlhere iay not be supe-fluoutos.Wenyon's original accotunt (1910) of tllis organism (" Macro-stoma1ft" m7es1nili) describes alnd figures its cysts as ovalstructures. Although oval anid even splhe'rical eystu, un-doubtedly oCCuI-, by far tlle commiolnest formi is tllat whichpossesses a protuberance at onie end, so that in slhape itclosely resellIbles a leimoni (seeFigs. 12 anid 14). Suchl Cysts:were first figured by Alexeieff (1912) for Chilomastix catd-leryi-a parasite of anmpllibia. Prowazelk and Werner(1914) figure a similar cyst as a "possible early stagein encystation" of the human parasite. Welnyoin (1915)further figures ani oval 4-nucleate cyst as belonging to thisspecies; btut tis, as we lhave sceen, is really thle cyst ofE. satana-ani er'ror whljiclh Wenvoni anid O'Connor (1917) havesince co-rected. Nevertheless, Swellenruebel and Winoto(1917) claimll to be able to distin)guislh tlhese cysts fromn Onioaniotlher. Finially, Lyncli (1916) has boldly describ)ed tlhocysts of Ch-ilomastiax esnliii as those of Tr-icho1mona8intes/inacii;. The only comiplete description wliiel Avehiave seen is that just pLublishied by Wenyoll and O'Connorin tIme vioilk quoted above.The cysts of Chlilomnastix 7nesnili, whether of the typical

lemoon shape (Fig. 12), round, or oval (Fig. 11), measureabouLt 7 to 10,A ii greatest diaineter. They niever containmiiore thani one nuclleus, whlichl is of large size tnd verychalracteristic styncture (Figs. 11 and 12). As its chroomatinis usuially conicenitrated at one pole, it is tvpically in theform-i of a signet ring. Snmaller masses of clhromnatin aresometim-es visible at other points oln thie nuclear memiibrane,biut rarely in thle ceutre. For thjis reason tlhe nuclei ofenicysted Chilomiastix often resem-ble those of tlhe unii-

nuIcleate cysts of E. sana (cf. Figs. 11 and 7). Thisresemnblanice is most striking in stained preparations; forin cysts examiniied in saline tlle nuclei of both are usuallyinvisible, wvlilst in iodine, although the Chilomzastixnuleleus can usually be mnade out as a definite signet ring(Fig. 14), onily tlho laryosome of the lnucleus of E. nanacal be distinauished with ease. The mnost distinctivefeature, hlowever, of the Chiloma8tix cyst is a complexstructure whichl represents tlje persistent part of tllemliouthi of the free flagellate. Tlhis structure resenmblesa slinig, its outlinie representing tlle fibre forming tllelip of tllc mouthl. Tlhe moutlh flagellumu, wlhichl in theflagellate borders an unduLlating membrane, can sometimesbe seen lying witliin tlhe sling (see Figs. 11 and 12).Tlhe melation of these parts to the tnucleus and blepharo-plasts is siinilar to thiat seen in tlhe free flagellate;but in the encysted forms the connexion between thesestructtu-es is ofteli severed. The outline of tlle noth9,tlhouglh usually invisible in cysts exanmined in saline, canas a rule be clearly seen in iodine preparations. Anotherfeature clharacteristic of tlle Chilomastix cyst is tlhepresence of a few sm-all aud briglhtly refractile granules..These, so far as we lhave been able t) investigate theirreactions, appear to be composed of volutin. The similargranules in tlle cysts of E. nana are usually smaller, lessrefractile, apd muo-e numerous. Anothier chlaracter, whicidoes niot appear to have been previously noted, is theoccasional presenice in tlhe Chilonzastix cyst of a mass ofglycogeni. ''ls nmass, whiclh stains very deeply in iodinesolution, is sometimes of very large size (see Fig. 14), audis present, we believe, in newvly-formed cysts only. Tlheoval cysts of Chiloinastix containing glycogeu may bemistaken for sitilar cysts of E. nana (Fig. 13); and bothmlust be distinguished froin tlle ustually muchieli larger cyst-like bodies described as " I-cyst. " by Wenyon (1916) andWenlyon and O'Connor (1917), whliiclh are niot uncommon inhiLumani faeces.Wenvon anid O'Connior (1917) have jutst described a new

intestinial flagellat whlliclh they call Tricer comonas intes-tinal.is. We lhave nlever fotund this flagellate ourselves,alnd fromii the puiblislhc(l account We are unable to statolhow its cysts can be distinguished with certainty fromthose of E. iana. We lhave seen cysts of this orgauismrlwlhiclh very closely resemble tlheir figures of tlhe cysts ofTr-iccrconzonas.Fro-m the fore(roing descriptions it will be evident tlat,

whVlen thle cysts are examinedl in saline and iodine solu-tions, the most outstanding clharactesrs diffe-entiatiaig

THxr BaIra 6tVL

EDICAL JOURNAIWAY 129 19T71

6i2 E BRNA POST-OPERATIVE TYMPANITES. [MAY 12, I91g

those of E. histolyltica, E. nana, and Chilomas8tix from oneanotlher are: tlle chromatoid bodies of the first, theapparently unifornly graniular contents of tlle second, andthe imioutlh of the tllird. It must always be remembered,of course, that tllc cysts lhere described form only a partof the numllerous sm-lall "bodies" commonly present inlhuman faeces. Somie of these are probably vegetableorganiisms resembling yeasts, others possibly cysts ofprotozoa as yet uniidentified. Altlhouglh we are familiarwitlh several different kinds of tlhese. we are not yet ableto determine and describe them satisfactorily.,

Although we are usually able to arrive at a 6ertaindiagnosis fromii a study of tlle cysts, it is sometimnesimpossible to reaclh definite conclusions when unencystedforms only are found, since tllese are all too often deadand degenierate. As already noted, E. nanza dies veryquickly after leaving the host. Tllis is also the case withitth6- siliall "minuta" forms of E. histolytica, and oftenalso witlh flagellate Chilomastix and Trichomionas. Theflagellates. wlhen they have degenerated to such anextenit that they are merely small rounded masses ofprotoplasm, devoid of flagella, are not distinguishablewith certainty frcom similarly dead and degenerateamoebae.An unencysted E. nana can easily be distinguisled,

when alive, from the small "'minuta " forms of E. histo-lytica by its pseudopodia, wllicll are never so hyaline andblade-like, and by the numerous food vacuoles (containingbacteria) wliicli are not seen in E. hi8tolytica. In botlforms the nuclei are very difficult to obs%ve in tlhe livinogorganism, though they serve to differentiate them withcertainty in good stained preparations (Figs; 1 and 2).Degenerate Chilomastix flagellates can usually be dis-tinguishlecl from degenerate small E. histolytica amoebaeof tlle " minuta " type by tlleir ingested bacteria anid tllepersistent outline of the mouth. It is often impossible todetermine wlhetlher a rounided-up and degenerate organism,in whiclh notlhing but vacuoles containinig bacteria can beclearly distinguislhed, was originally a Chilomizastix or anlE. nana. Sucll forms are almost certainlX not "mviinitta "

amoebae, but, in the absenice of cysts, adfurtlher diagniosiscanniot be made witlh certainty. Tlle degelnerate formjis ofTrichomoznas can usuLally be distinguished by the peculiarundulating " amoeboid"imovement wllich they oftencontinue, to display for a long time.

Altlhough E. nanca dould ha rdly be mistalken for the nmucllarger E. coli, witlh its siinilar inclusions but clharac-teristic nucleus, it miliglht be confused witlh one of tllesmall so-called "limtax" amoebae somietimes found instale stools. If the stool is muore tlhani a day old and theamoebae are actively mnotile on a cold stage, it is certaintllat tlley belong, not to any species of Entamzoeba, but tosome free-living form. Although it is ustual in miedicalworks to include all tlhese small free-living amoebae undertlhe term " Amoeba linzax," there are probably miianydifferent species belonging to quite different groups wllicmay occur in hluman faeces. A comnmon form is slhown inFig. 3 for conmparison witlh E. histolytica (Fig. 1) andE. naqna (Fig. 2). The most distinctive characters of thisand related forms are the nucleus, with its large centralkaryosome, and the presenlce of a contractile vacuole.Some free-living amoebae possess more tllan one con-tractile vactuole, but such structures are never found in anyspecies of Entamoeba. All the common " liiax" anmoebaeform uninucleate cysts, wlliclh, in typical forms, cannot bemistaken for those of any Entamoeba. Tlle cyst wallis always tlhick and frequently-but not always-veryirregular in outline and brown in colour (see Fig. 10). Thesingle large nucleus usually lies near the centre, sur-rounded by numerous deeply-staining masses, probablyhomologous with the chromatoid bodies of soeue entamoebiccysts. Most of these small, free-living amoebae can bereadily cultivated on agar.The figures accompanying this paper lhave been selected

in order to illustrate the more important points consideredabove. We have thought it superfluous to give new figuresof the more familiar forms. Accordingly, of the threecommon intestinal amoebae with which this paper chieflydeals weAhave figured only certain forms of E. histolutirca,and F. nana, whlilst F. colti is unrepresented and twoother organisms are adKded.

Thle observations here recorded hlave been mzade in theceourse of Work undkertaken with thie aid of grants from thle

Medical Research Committee. They have been nade, forthe most part, whilst enjoying the hospitality of theWellcome BLureau of Scientific Research, to wliclh we heregladly acklnowledge our indebtedness.

BIBLIOGRAPHY.Alexeieff (1912): Zool. Antz.. vol. xxxix, p 674.Cbatton and Lalung-Bonnaire (1912): Bull. Soc. Patliol. Exot., vol. V.

p. 135.Dobell (1916): BRITISH' MEDICAL JOURNAL, November 4th, p. 612.Elimassian (1909): Centralbl. Bakt., I Abt. (Orig.), vol. lii, p. 335.JaiJames (1915): Amt. Tro2p. Mfed. Parasitol., vol. viii, p. 133.i1Kuenen and Swellengrebel (1913): Centt-albl. Bakt., I Abt. (Orig.)d

Vol. lxxi, p. 378L3nch (1916): Tou?rn. Pa-asitol., vol. iii, p. 28.Mathis and AIercier (1917): Bull. Soc. Pa'7hol. Exot., vol. x, p. 165.Prowazek andl Werner '1914): Arch. Schiffs- it. Tropei7iyg. Beih. V,

vol. xviii, 1). 155.Slmiith &nd Matthews (1917): Annt. T-op. Med. Parasitol., vol. x,.361.

t Swellengrebel anid Schiess (1917): Bull. Soc. Patliol. Exot., vol. X..13.Swellengrebel and Winoto (1917): Parasitol., vol. ix, p. 266.Wenyon (1910): Ibid., vol. iii, p. 210. (1913): BRITISH MEDICAL

JOURNAL, NoveuIber 15Uh, p. 1287. (1915): jou?n. B A M.C., vol. xxv.p. 600 (also Lan cet, November 27th). (1916): Ibid., vol. xxvi, p. 445.Wenyon and O'Connor (1917): Ibid., vol. xxviii, pp. 1. 151, 346.Woodcock and Penfold (1916): BRITISH MEDICAL JOUJRNAL, March

18th, p. 407.

POST-OPERATIVE TY31PANITES:ITS NATURE AND SOME POINTS IN ITS TREATMENT.

BY

JOHN D. MALCOLM, M.B., C.M.EDIN.,SURGEON TO THE SAMARITAN FREE HOSPITAL.

IN tlle Cavendisli lecture of 19151 Professor ArthurKeitlh described a neuro-muscular tissue specialized fromAuerbaclh's. plexus of nerves and situated where delaysin the passage of the bowel contents normally take place.He regarded the myeniteric plexus of the intestine assiinilar in nature aild functions to the nodal and con-ducting systeimi of the lheart, eaclh specialized nervousarea in the alimentary canal being the regulator of peri-staltic activity in tlle part of the intestine immediatelybeyonid it. According to tllis view, a want of co-ordinationbetween tlle mnscular activity of the various partsmay give rise to effects comparable to tllose of lheart-block, and it was concluded tllat the condition of intestinalstasis is broughlt about by sucll a want of co-ordination offunctioin.

Keitlh's teaclling supports certain views wllich I havelong held. At tlle miieeting of thlis section in October, 1914,2I attributed the tympainites following somne abdominaloperations to an enfeebled peristaltic action, and especiallyto delay in the large bowel. I suggested tllen that tllecondition miglht be described as one of acute intestinalstasis. Five cases wvere published in whiclh an otlherwiseirremovable tyrinpanites following an operation upon theabdomen was treated by making an intestinal fistula, andiour of tlle patients recovered. Thle fiftlh died, and itseemned to miie that in this case the second operation was toolong delayed, and tllat it could not lhave been uindertaken tooearly. I argued tllat if a persistent tympanites can be'cured by making a fistula its onset should be preventableby tlle same miieans, anid tllat treatmient by prevention insuitable circumistances would be more certain of successthan any methlod of cure. Tllis view was put into practice,and two cases were recorded" in whi-ch a caecal fistula wasmade whlen intestinal difficulties seemed likely to arise.Recovery was uncomplicated by any bowel symptoms, andI lhave since treated eleven cases in this way with twofailures, and assisted at one successful operation for therelief of a fully developed tympanites. In the tensuccessful cases the fistula was closed after a short time.To save space only four cases are here briefly recorded.

CASE I.On the second( day of acute symptoms a diffuse peritonitis

was found affecting the pouch of Douglas, the Fallopian tubesa(ld the intestine and mesentery in the lower portion of theabdomen. Much lymph floated in free fluid or adhered in thicklayers to the parts named, except the Fallopian tubes. Thesewere of a deel) blue colour, and greatly enlarged by oedema.They contained no pus and were not removed. All the in-testines in the middle and upper abdomell were- d andmoderately distended. The vermiform appendix showed signsof old inflammation and was removed, but it lay outside the

* Abstract of a paper read at a meeting of the Section of Obstetricgand Gynaecology of the Royal Society of Medioine,