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On the new medium (sec Chart 1) 8. (’oli tend to bevery much larger, being on an average at least, doublethe size of B. coli obtained from the same stoolcultivated on ordinary agar. When transferred to

ordinary agar they are very much smaller in size andwhen retransferred to the new medium they againtend to increase materially in size ; yeasts, alreadyreferred to, are scanty in numbers in the first cultureand rapidly increase so long as subcultured on the newmedium. When transferred to ordinary agar they ’rapidly decrease until they disappear or their presence iis not revealed.

In Chart 2 corresponding results are revealed asregards the morphological appearance of B. coli,the bacteria being notably small on ordinary agarand notably large on the new medium ; in thischart it is similarly interesting to observe the lateappearance of yeasts in the new medium under theconditions described, also their rapid increase and theirapparent rapid disappearance when transferred toordinary agar.The further consideration of the nature and clinical

significance of the altered proportion of organisms thusrevealed, and also their differentiation, is beyond thescope of the present communication. I am satisfiedthat the new medium, while definitely favouring thegrowth of streptococci, does not inhibit the growthof coliform organisms. In a later paper atten-

tion will be directed to the influence of the newmedium under anaerobic conditions. The practicalimportance of the data is suggested by a considerationof the fact that at the present time vaccines preparedby culture from the stools are extensively employedin the treatment of a variety of diseases with varyingresults ; these are ordinarily prepared from the

organisms which grow on the media in common use.My experience in this direction leads me to think thatin many instances in which there is a profoundderangement of the normal flora, the cause is to befound in relation to the bacteria which do not readilygrow on the ordinary media but are revealed by theuse of the new medium.

There are many questions of a nature more purelybacteriological, and also clinical, raised by thesefindings ; their solution will necessitate much furtherinvestigation. The possible significance of variationsin hydrogen-ion concentration of the media has notbeen overlooked. My main object has been to drawthe attention of bacteriologists and others to the factsrecorded, with the view of stimulating investigationalong lines which I am satisfied will prove of value inelucidating the wide and important subject ofintestinal toxaemia.

I have pleasure in expressing my indebtedness tomy laboratory assistant, Mr. John Linklater, for hisvaluable assistance in these investigations.

Medical Societies.THE MEDICO-LEGAL SOCIETY.

ACUTE ARSENICAL POISONING.

A MEETING of this Society was held at the rooms ofthe Medical Society of London on July 4th under thepresidency of Lord Justice ATKIN, when Sir WILLIAMWILLCcox read a paper on Acute Arsenical Poisoning.He said this subject had always been of great interestand importance to the medical and legal professions.During the last few years our knowledge of thephysiological, therapeutical, and toxicological effectsof arsenic had been greatly extended, owing largelyto the much increased use of preparations of arsenicin the treatment of disease, such as arsenobenzolderivatives in the treatment of syphilis, while otherarsenical compounds were used in pharmacology. Insome cases toxic effects had followed when the ’substance had been used therapeutically. Theextended use of arsenic had also stimulated a careful Istudy and review of various quantitative tests for ithe degree of efficiency of such organs as the liver. j

Recent Advances in Knowledge of Arsenic Riskfrom Domestic Employment. ;

Arsenic was one of the commonest and oldest known ipoisons ; it was believed to have been discovered in ithe third century. Everybody knew of its poisonousproperties, and preparations of it were easily accessible.It was almost tasteless, and could be introduced into ifood without fear of it being detected by those taking iit. As the symptoms following closely simulated Ithose of disease, it had been a favourite homicidalpoison for centuries. Poisoning by arsenic might be Ihomicidal, suicidal, accidental, might follow anattempt to procure abortion, or might result from !taking quack remedies. Of 1000 cases of arsenical Ipoisoning collected between the years 1752 and 1911,42 per cent. were homicidal, 23 per cent. suicidal, 20 per cent. accidental, 3 per cent. were cases in whichthe drug was taken as an abortifacient, and in 10 per ’,cent. the motive was not ascertained. But these figurescould not express the true proportions, as the suicidal iand accidental cases were not usually reported. For:criminal purposes the most common preparation,used was arsenious oxide, a white, inodorous powder,almost tasteless, and slightly soluble in water, and itcould be added to food without fear of detection. It I

was required to be coloured by soot or indigo beforebeing sold, but sometimes, as in the recent Armstrongcase, this was not carried out. The poison could beobtained from wholesale firms for laboratory purposesalmost without restriction, and it was available toall and sundry who used or passed in and out of suchlaboratories-a source of possible supply not usuallypaid attention to. Arsenious oxide was sold in com-bination with sodium hydrate or carbonate as weed-killer ; it might be a strong solution of sodiumarsenite. The liquid preparation was usually colouredby the addition of an aniline dye, such as fluorescine." Ureka " weed-killer was mentioned in the Greenwoodcase, and a sample of that brand contained 60 percent. arsenious acid. It was very soluble in water, andformed a pinkish-red solution, which was decolorisedby acids. In the case of Rex versus Bingham, 1911,three fatal cases of arsenic poisoning were inquiredinto, and they were found to have been due to weed-killer. Liquid preparations of arsenic were used tokill insects which infected and destroyed the strengthof timber, and as these were not coloured there wasdanger of unwitting poisoning ; a hut which had beenso treated was found to exude a white powder which! was found to be arsenic. Sheep dips also containedthis poison. Arsenate of lead solutions for sprayingfruit were also a potential danger; Sir WilliamWillcox had had cases due to this under his care, andurged a reconsideration of the conditions of their saleas a protection against danger to the general public.Also, especially when large doses were given, the riskof arsenical poisoning from taking medicinal prepara-tions could not be left out of account.! The Symptoms of Poisoning by Arsenic.

Arsenic had been described as an irritant poison,but death from it was not directly due to its irritanteffects on the gastro-intestinal tract ; it was a verypowerful tissue poison, and the fatal result was dueto its toxic effect on the important organs of the body- heart, kidneys, liver in particular. The vomitingand diarrhoea, which per se were rarely the causeof death, and could be easily controlled by medicinalcare. The symptoms of arsenical poisoning varied agood deal as to their sequence and the period of theironset, hence no rigid rule could be stated. A toxicdose of arsenic might in one person cause vomiting firstand diarrhoea afterwards, but in another the ordermight be reversed. Some might complain of a

burning in the throat and cramps in the legs, whilein others these might be absent, though a similardose had been taken. In some criminal cases a

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succession of sub-lethal doses had been given, eachdefinitely poisonous ; here the symptoms whichwould be expected to follow one large dose would besomewhat masked by the symptoms of subacute orchronic poisoning. When one or two grains weretaken by the mouth nausea was usually the firstresult, and it might occur within a few minutes oftaking the poison. The time of onset of the symptomsdepended on the state of the stomach when thepoison was taken. If it was empty, symptoms wouldquickly follow ; if a meal had just been taken, or ifthe arsenic was in a solid form, symptoms wouldbe delayed. Sir William Willcox related one case inwhich 180 grains were accidentally taken in milk ;diarrhoea and purging followed, and these symptomswere treated, so that death was postponed until3! months after the arsenic was taken, showing thatthe main action had been that of a protoplasmic poison.A worker in the laboratory of a weed-killer firm some-times had diarrhoea and vomiting at night, no doubtdue to the inhalation of minute quantities of arsenicthroughout the day. As arsenic was not a corrosivepoison it was difficult to account for burning in thethroat, except by reflex action. The vomitedmaterial would contain food and mucus, sometimesan admixture of blood ; occasionally it was yellow,owing to the presence of bile. Pain and tendernessin the abdomen were followed by a profuse evacuation ;the stools were watery, and might contain smallquantities of mucus and blood. In cases of suspectedpoisoning, the stools should be carefully preserved foranalysis. In the early stages the tongue was furred,and later might have a silvery appearance. Afterrepeated administration of the poison sordes mightappear on the lips. The vomiting and diarrhoeawould produce great thirst, and the face mightbecome so pinched-looking that there was some

resemblance to a case of cholera. One of the earliestand most constant symptoms was a weak and rapidpulse. Both Mr. Martin and Mrs. Armstrong, in therecent Armstrong case, suffered from tachycardia.This was accompanied by a feeling of faintness and ofimpending collapse. Sir William Willcox said thatarsenic had a direct action on the cardiac muscle, andthat- was a reason of early death in acute cases. Itwas also a direct liver poison, and in fatal cases of thiskind the organ showed marked fatty degeneration.One function of the liver was to protect the bodyfrom the effects of any circulating poisons; hencein bearing the brunt of the attack in a case ofarsenic poisoning it was often irreparably damaged.Jaundice was not a common symptom of acutepoisoning by arsenious oxide, but it was likely to occurwhere the doses of poison had been extended oversome weeks. Acute yellow atrophy of the liver mightfollow the poisoning. Many cases of salvarsanjaundice had now been recorded, and it was evidentweeks, even months, after the administration of thesalvarsan. After the clearing up of the jaundice theliver was usually left shrunken, arsenic causinghepatic degeneration. There was also albuminuria,and in one case examined there was definite arterio-sclerosis of the kidney. The lead in some fruit-sprayers accelerated the renal symptoms.When salvarsan was first introduced, there were a

number of deaths from it, and they resembled deathfrom uraemia. Nerve symptoms did not result froma single dose of arsenic unless it were a large one ; thenmultiple neuritis might ensue. The latter was

frequent in cases in which there had been smaller andrepeated doses of the poison. Not only was very littlearsenic found in the brain in these fatal cases, but themental condition was usually unimpaired until a fewhours before the end. When cerebral symptomsoccurred they were due to auto-intoxication.

,Fatal Dose and Fatal Period.A single dose of 2 gr. of arsenious oxide had caused

death in a healthy adult, and this was usually acceptedas a possible fatal dose. It was common for muchlarger doses to be taken and recovery to occur, dueno doubt to the rapid elimination of the poison by

vomiting and diarrhoea. A certain quantity ofarsenic if given in solution and spread over a shortperiod in its administration was much more likely toprove fatal than the same amount taken in one dose.It was impossible to state what was the fatal period,as so many factors influenced it. Usually the endcame in three days, but in a case of repeated smalldoses, death might be postponed for many days.In one case death occurred 20 minutes after thetaking of a large dose, whereas in another, after a doseestimated at 180 gr., death did not occur for 3 zmonths.

Post-Mortent Examination.

Dealing next with post-mortem examination, SirWilliam Willcox said that in cases in which poisoninghad occurred for some time previously, careful searchmust be made for evidences of delayed putrefaction.But too much importance must not be attached to thissign, for when death had quickly followed the takingof a large dose there might be very little delay inputrefaction. Signs of inflammatory trouble instomach and intestine, and especially petechialhaemorrhages, should be looked for ; there might beno such evidences when death had taken place severaldays prior to the examination. He stated the pre-cautions which should be observed when sendingviscera and portions of organs for examination insuspicious cases ; each should be placed in a separatevessel, and the caecum and other portions of intestineshould be sent ligatured to prevent escape of contents.A portion of muscle, a piece of bone, some hair cut offclose to the scalp, a portion of skin and the nailsshould be separately preserved. Any fluid in thecoffin in an exhumation case should be kept, also anyearth adherent to the coffin.

Chemical Tests.He then proceeded to deal in detail with the

chemical tests for the presence of arsenic. The Reinschtest he regarded as the best for qualitative purposes.Where a weighable quantity of arsenic was available,the sulphuretted hydrogen test was to be preferred,and for minute amounts the electrolytic MarshBerzelius test gave excellent results. But toxicologicalwork should not be confined to one test, nor shoulda conclusion be based on examination of one viscus.Numerous examples had occurred where the origin ofarsenic found in the process of analysis of viscera wasfound to be the impure chemicals used.

Elimination of Arsenic.In acute arsenical poisoning the vomit and faeces

contained arsenic in amount depending on the quantityof the poison taken. As to the blood, 0-5 mg. ofarsenic had been found in 100 c.cm. of blood after givingsalvarsan, and the urine continued to contain it for14 days after the drug was given. After considerabledoses of arsenobenzol it might continue in the urinefor three weeks : in one case it was found 15 monthsafter the patient had received ten injections ofsalvarsan. In acute cases of poisoning it was excep-tional to find arsenic in the urine for longer than aweek or ten days after the administration of the poison.In cases of prolonged administration arsenic, havinga strong affinity for the keratin tissues, was found innails, skin, and hair, especially in the proximal por-tions which had grown since the arsenic had beengiven. Distal portions of the hair which had been incontact with sweat or blood-stained fluid might absorbarsenic therefrom ; this had occurred in the Armstrongcase. Arsenic might be found in the sweat, saliva,bronchial secretion, and even in the milk, as well as inurine and faeces. However, in two cases wheresalvarsan was given to patients during lactation SirWilliam Willcox had been unable to find arsenic insamples of milk taken from 5,1F to 72 hours afterthe administration, so that any benefit to the childresulting from the administration of arsenic to themother could not be due to the presence of arsenic inthe milk.

1 THE LANCET, April 22nd, 1922.

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Distribution of Arsenic in the Body in Fatal Cases.The distribution of arsenic along the intestinal

tract in fatal cases was important, as it gave infor-mation as to the probable time of the administration.Usually the liver contained a considerable quantityof the drug. In acufe salvarsan poisoning there wasmarked fatty degeneration of the liver and kidneys,and usually the heart muscle would be damaged. In

using salvarsan, the risks from its toxic powersshould always be present to the mind ; this danger,Sir William Willcox thought, was usually treated toolightly; yet the number of venereal clinics now estab-lished made it a very important matter. Liver andkidney changes might occur weeks, or even months,after the use of the arsenic compound. It had beenpointed out that much of this danger could be avoidedby giving the patient glucose shortly before usingthe anti-syphilitic injection ; the truth of this hadbeen confirmed, and it was a course which should beuniversally followed.The lecturer concluded by passing onto the screen

records of the clinical and pathological findings inrecent notorious poison cases, using the occasion toemphasise the lessons which recent research hadtaught. He also showed specimens of weed-killer,syringes, and other interesting exhibits in connexionwith criminal cases.

Discussion.The PRESIDENT, in conveying the Society’s thanks

to Sir William Willcox, expressed the view that thepaper would prove historic, by reason of its thorough-ness and clearness. He alluded to the importance ofthe fact that the symptoms following a poisonousdose or doses of arsenic closely simulated those ofnatural disease. He spoke in appreciative terms ofthe value of Sir William Willcox’s work in furtheringthe administration of justice. The latter had referredto the importance of regulating the sale of arsenic,and possibly it would be wise to impose furtherrestrictions, though it appeared doubtful whetherthese would be of any practical use.

Dr. F. S. TOOGOOD asked whether the dispositionof arsenic in the body after that body had lain a yearor so was the same as that immediately following death.

Dr. BERNARD SPILSBURY referred to the danger ofarsenical poisoning as a result of leakage from chemicallaboratories ; many students of science at the presentday had access to these poisons, and to bacteriologicalpoisons ; hence these laboratories formed a seriousphase in this problem. He was convinced that theinjection of the organic arsenic compounds in thetreatment of syphilis was a danger of considerableimportance. A large number of patients who com-menced treatment at venereal clinics ceased beforethe course was complete, and the cause of this dis-continuance was probably largely due to the injuriouseffects they had experienced from the injections.There had been a number of deaths of persons inwhose stomach arsenic was found, but there wasdifficulty in ascertaining their history because of theconditions of secrecy attending the treatment of thesyphilis. This was an aspect of the subject whichthe Ministry of Health ought to take steps to meet.

Earl RUSSELL thought Sir William Willcox’swarning in regard to the possible dangers of treatmentby salvarsan was much needed.

Sir WILLIAM WILLCOX, in reply to Dr. Toogood,said there were cases in which one could draw no

conclusion from the way the arsenic was distributed z’

in the body, especially where putrefaction hadoccurred and the tissues were liquefied. The valueof the opinion formed depended on the condition ofthe body at the time the examination was made, andthe probable condition of the body since death. Inthe Armstrong case Dr. Spilsbury was satisfied thatthe arsenic found in the caecum had been there duringlife ; but there were in some cases conditions ofputrefaction in which such a deduction would notbe justified. Each case must be judged individually.The fact that traces of arsenic were detectable manyweeks after receiving the last dose of salvarsan

added an element of considerable difficulty to toxico-logical cases of arsenical poisoning ; and this factorwould have to be very carefully considered by thosewho happened to be investigating a particular case.It was not possible to distinguish during analysis,whether the poison was inorganic arsenic or arseno-benzol derivative.

ROYAL SOCIETY OF TROPICAL

MEDICINE AND HYGIENE.

THE annual general meeting of this Society washeld at 11, Chandos-street, on June 22nd, with SirPERCY BASSETT-SMITH in the chair.

Trypanosomes in the Human Brain.

Dr. A. C. STEVENSON gave a demonstration of micro-

scopical sections of human brain showing markedsmall-celled infiltration round the blood-vessels, andthe presence of trypanosomes in the white and greymatter of the frontal lobe, in the pons Varolii andupper part of the medulla oblongata of a case ofchronic sleeping sickness. Although trypanosomes,had previously been demonstrated within the lumenof cerebral capillaries in cases of sleeping sickness,Dr. Stevenson believed that his specimens are thefirst to show the parasites lying between the nervecells free in human brain tissue.

Anopheles and -I[alctria Control in Trinidad.A paper by Dr. ERIC DE VERTEUIL on Anopheles.

and Malaria Control in the Brighton-La Brea RuralSanitary District, Trinidad, was read in abstract byDr. ANDREW BALFOUR. A number of lantern slideswere also shown. The particular area of Trinidadwhere Dr. de Verteuil had been engaged at work since1919, as medical officer to the Trinidad Lake Asphaltand Petroleum Companies, has a pitch lake of 80 acres,and extensive oil-fields in the neighbouring forest.

Malaria has for long been prevalent despite effortsby the company during the past decade to controlthe spread of infection by screening the bungalows,by attention to drainage, and by clearing of grasson the estates. An unprecedented invasion bythe anopheles at Brighton-La Brea, in August,1920, led to the adoption of vigorous anti-malarialmeasures. The grass was cleared away by mowingmachine and cutlass for a radius of 200 yards fromall bungalows and buildings, and all drains withinthat area were brushed, cleaned, and graded. Otherbreeding-places were filled in or drained or treatedwith crude oil. The cleared drains were then burntout with an oil mixture, fed by a hand-pump spray ;this had the effect of suppressing the growth of grass.for three months or more. Within a few weeks;anopheles was reduced to very small numbers, butthe effect was only temporary ; in 1921 the use ofTrinidad liquid asphalt and sanitary oil for the treat-ment of the drains was introduced. A mixture ofliquid asphalt and sand, allowed to flow ignited alongthe course of the open drains, and the spraying ofsanitary oil on the blazing asphalt effectively destroyedall growth in and on the sides of the channels. Whencool there remained a firm smooth lining of asphaltand sand which provided a durable and impervious.surface, capable of resisting the scouring of the waterand preventing growth of vegetation in the drainfor a long period. Where the gradient was too steepfor the asphalt to remain set, the heat generated wassufficient to bake the clay to a state of resistant hard-ness which served much the same purpose as theasphalt lining. The cost of lining surface-drains inthis manner was estimated at between 14 and 20 centsonly per square yard, as compared with one dollarper square yard of concreting. The result had beenthe extermination of mosquitoes from the districtand a great reduction in the cost of upkeep of thedrains. The drain so treated must be dry at the time ;if the flow of water was continuous throughout the