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every kind of accident or disease. The Chancellorof the Exchequer pointed out recently that an" aJl-in " method of insurance would present enormousdifficulties, administrative, political, and economic.Nevertheless, Great Britain may some day decide tounify and coordinate the whole of its social insurance,health insurance, unemployment insurance, work-men’s compensation, employers’ liability, old agepensions and all. When that day comes, the medicalprofession must be ready to take its part in the

framing of the scheme as well as in the operation ofthe machinery.

DIRECT INFECTION IN ENCEPHALITISLETHARGICA.

THE account of an outbreak of encephalitislethargica in a school at Radway, Warwickshire,which we published in a recent issue,’ is worthy ofclose study by those who may be called upon to

diagnose this disease. Dr. L. L. FYFE has chronicledmany interesting and important details concerning thesymptomatology and clinical course of the disease asmanifested in this instance by young children. Theevents at this small school, however, are significantin a wider sense, for they shed further light on thenatural history of encephalitis lethargica and help tomake more clear the infectious nature of this epidemicdisease. As formerly, with acute poliomyelitis andcerebro-spinal fever, so now with encephalitislethargica, the personal incidence of the disease seemsat first sight to be a matter of mere caprice on thepart of the virus, and well-marked cases of the maladycrop up in apparently sporadic fashion throughoutthe country. There still remains a strong impressionthat, even when the disease is comparatively prevalentand widespread, the individual cases occur as discreteand unconnected events. In 1921 MACNALTy 2

recounted instances where multiple cases of infectionhad occurred, and later further instances of case-

grouping were brought to light in this and othercountries. In a severe wave of encephalitis lethargicathat ingulfed certain villages in Lapland duringFebruary, 1921, the morbidity rate 3 was unprece-dented and varied from 7.1 to 45.0 per cent.; wholefamilies were involved, and side by side with acutetypical cases were others in which the disease showeditself in various degrees of comparative mildness.

In this country the " Derby outbreak " of August,1919, investigated and described by lVIcNr.Ty,4in addition to demonstrating the infectious poten-tialities of the disease, provided the occasion for

establishing on bacteriological grounds some new

facts concerning the virus itself. It will be recalledthat this explosive outbreak occurred in a home forgirls, and- out of a total community of 22 persons12 individuals were attacked within a fortnight. Thefirst two cases were probably infected from a commonsource-latent in the home itself or encounteredoutside-but it is likely that direct contagion accountedfor the majority of cases. As an instance of infectionclinically affecting many members of an institutionthe experience at Derby remained unique until theoccurrence of the small outbreak recorded by Dr.FYFE ; at Derby the disease, with dramatic abrupt-

1 THE LANCET, Feb. 24th, 1923, p. 379.2 Encephalitis Lethargica as an Epidemic Disease. Inter-

national Journal of Public Health, May to June, 1921, ii.,No. 3.

3 Kling and Liljenquist : Hygeia, Stockholm, 1921, lxxxiii.,566-72.

4 Report on Outbreak of Encephalitis Lethargica in a Girls’Home. Ann. Rep., Chief Medical Officer, Ministry of Health,1919-20, App. VII.

ness, fell upon a secluded community of youngwomen (the majority of whom belonged to the mostvulnerable age-period), quickly involved over half ofthe inmates, and caused the death of five of thoseaffected. Of the 32 scholars at Radway a smallerproportion were infected ; the invasion of the diseasewas insidious and for some time unrecognised byreason of the comparatively long interval between thefirst and subsequent cases and of the relative mildnessof the clinical symptoms. The school had but latelyreassembled after the summer holidays when, on

Sept. 15th, one of the older girls was found to be fastasleep at her desk ; with some difficulty she wasroused sufficiently to be sent home, where she remainedfor a long week-end and then resumed her regularattendance at school although subject to daily boutsof somnolence and headache. On Oct. 9th the seniorgirl in the school, who occupied a seat immediately infront of the first patient, was overcome in a similarway, and on the llth and 13th respectively two moregirls were attacked. Alone among her school-mates,the first girl had spent part of the previous holidaysaway from the village ; it would seem likely that sheacquired her infection while on a visit to a neighbouringlarge city, and that the last three children to beaffected derived their infection either directly or ina mediate manner from her. This would mean an

average incubation period of 23 days. On the otherhand, if the second case passed on the infection toone or both of the others the incubation periods wouldbe considerably shorter and more in accord withevents in the Derby outbreak. At any rate, it is diffi-cult to avoid the conclusion that personal contagionwas the method of spread here as it probably was inan instance reported by REECE,5 where a nurse con-tracted the disease while attending a patient who wassuffering from encephalitis lethargica and with whomshe had not previously been in contact. Moreover,the instances of encephalitis lethargica in babies,born while their mothers were suffering from thedisease (four such instances have been recorded inthis country), surely must dispel any doubt as to thecontagiousness of the malady.

Investigation failed to discover any obvious focusof infection with which the first patient at Radwayschool had come in contact during her holiday visits ;but, it is noteworthy that, in at least three instances,where there was a familial grouping of cases in isolateddistricts, the first patient to be attacked had recentlybeen visiting a populous centre. Again, the com-parative frequency with which the more strikingexamples of multiple infection are referable to isolateddistricts or secluded communities is one of the most

significant features in the epidemiology of encephalitisj lethargioa. It would almost seem as if the dwellers inpopulous centres had, through constant contact withinfection, acquired an immunity to the virus whichhas not been possible for smaller communities livingin comparative seclusion. When, however, a sus-

ceptible member of such a community mixes with theworld at large he may acquire the virus and on

returning infect one or more susceptible persons in hishome or place of work. The researches of LEVADITI,HARVIER, and NicOLAii, indeed, appear to show (assuspected for some time on clinical and epidemiologicalgrounds) that the virus of encephalitis lethargica iswidespread and exists in more than one form ; it is

perhaps sufficient for the clinician and the epidemio-logist to know that there are " carriers " who harbourthe virus in virulent form and that, in an attenuateddegree, the poison lurks in the saliva of healthy

5 Encephalitis Lethargica. A. Prevalence in 1918-19. ReportMedical Department of the L.G.B. for 1918-19, p. 71.

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individuals. Another lesson may well be learnedfrom the little outbreak. It is the custom in many amedical inquiry to search for clues among the denserareas of population, to use the weight of mass

statistics, and to avail ourselves of the technicalfacilities and professional experience which are to befound in all important centres. But in the case of

encephalitis lethargica, and some kindred diseases, amore fruitful field for inquiry will often be found inthe less populous districts where the threads of aninquiry can be more easily caught up and the knotsmore quickly unravelled. Not in cities, nor in

hospitals, then, but in such quiet rural retreats asRadway village may be found the solution to some ofour epidemiological problems, and in such quests thecountry practitioner, the village schoolmistress, andthe health visitor can render invaluable publicservice. Indeed, they have done so.

ADVANCES IN CANCER RESEARCH.

EXPERIMENTAL cancer research is at the presentmoment perhaps one of the most active departmentsof medicine. The two last volumes of the Proceedingsof the Japanese Pathological Society1 contain out ofless than 200 papers over 30 papers on experimentalcancer research. Last year an informal international

meeting of a number of leading investigators in

experimental cancer research was held in Amsterdamunder the presidency of Prof. ROTGANS, of Amsterdam,which led to the formation of the Leeuwenhoek

Vereeniging, a society for the study of malignanttumours. The first meeting, which was held withoutostentatious publicity last October, dealt exclusivelywith the subject of tar cancer. The Proceedings2now published as an unpretentious volume of 53 pages,represent one of the most important publicationswhich have as yet appeared on the subject of cancer,since it summarises investigations which are proceed-ing in the different leading laboratories. Owing tothe distance, Prof. YAMAGIWA, of Tokio, and Dr. W. H.WOGLOM, of New York, who had been invited, wereprevented from being present and reporting on theirinvestigations. The slim volume contains contributions by Prof. J. FIBIGER, of Copenhagen, thefather of this line of cancer research, and his assistant,F. BANG ; by Dr. H. T. DEELMAN and Dr. WATER-MAN, of Amsterdam ; Dr. J. A. MURRAY and Dr.A. LEITCH, of London ; G. RoussY, R. LEROUX,and ED. PEYRE, of Paris ; B. LIPSCHUTZ, of Vienna ;R. BIERICH, of Hamburg ; BR. BLOCH, of Zurich ;and A. TEUTSCHLANDER, of Heidelberg.

In reading through these reports one cannot helpbeing struck by the significant advance which has takenplace during the last four years in our knowledgeof the aetiology of cancer. The same impression isgained from reading a recent paper by Prof. FIBIGER,which gives an admirable summary of the recentwork on the experimental production of cancer.

Some of the most fundamental problems, the solu-tion of which has defied the efforts of clinicians andmorbid histologists for half a century, yielded theirsecrets as soon as the experimental method could beapplied. In fact, it may be doubted whether the

1 Verhandlungen der Japanischen Pathologischen Gesellschaft,10 Tagung, 1920 ; Transactions of the Japanese PathologicalSociety, vol. xi., 1921, published by the Pathological Instituteof the Imperial University, Tokio.

2 Leeuwenhoek Vereeniging, vol. i., J. M. de Bassy, Amster-dam, 1922.

3 Acta Chirurgica Scandinavica, vol. lv., 1922, p. 343.

problem of the aetiology of cancer could ever havebeen solved if the clinical study of the disease in manhad been our only mode of attack, for the experi-ments with tar have shown that a tumour maydevelop long after the irritant ceased to act. Fromthis discovery of a long " period of latency " whichin man may extend over years, a number of importantconclusions follow. Thus cells may have acquiredthe tendency to develop later malignant propertiesbefore there is an external indication of this changein their morphological appearances. Again, thecharacteristic age-incidence of cancer is not due tothe fact that the cells of old animals are more proneto cancerous degeneration than the cells of younganimals. Experiment shows that they are’not; thecorrect explanation is that the irritant must act overa considerable period, to which has to be added theperiod of latency. i There is further the importantdemonstration that tumours which are apparentlybenign may develop into malignant new growths,and that a trauma which by itself is incapable ofproducing cancer will greatly accelerate the develop-ment of cancer following upon the application of asuitable irritant. This last fact throws light on theoccurrence in man of malignant new growths after atrauma and at the site of the trauma. If there is acausal relationship it is probably that the traumashortened the period of latency. Attempts to immu-nise mice against the development of cancer have sofar failed. The methods which will produce a

resistance against the homologous transplantation oftumours do not confer resistance against the develop-ment of cancer any more than they confer resistanceagainst the autologous transplantation of tumours.

Lastly, there is the significant fact that mice whichhave once developed a cancer after the applicationof tar, and have been cured by operation, do not reactto the subsequent application of tar by the develop-ment of a second cancer. This fact explains the com-parative rarity of the occurrence of multiple tumoursin man, and may lead to other important developments.At present there is at any rate some consolation in thereflection that, probably, we can have cancer but once.We have only indicated here some of the definitely

ascertained results concerning the aetiology of cancerwhich have been obtained. But it is clear that since

malignant disease can be produced experimentallytherapeutic and prophylactic measures can now beplaced on a controlled experimental basis. The workis necessarily slow and requires a good deal of patience.It takes months in a mouse, and over a year in a

rabbit, even to produce a new growth, and the mor-tality is high. This may account for the curiouslack of appreciation of the significance of this workoutside the narrow circle of those who are engagedon it, and for the failure of the wider medical publicto realise that, so far as cancer research is concerned,we live in stirring times.

PUBLIC HEALTH QUESTIONS IN BELFAST. - TheBelfast City Council is promoting a Bill in the Parliament ofNorthern Ireland to secure wider powers for dealing withthe food-supply of the city. To consider these proposalsa joint meeting of the Ulster Medical Society and the UlsterBranch of the British Medical Association was held in theMedical Institute, Belfast, on March lst, with Prof.J. A. Lindsay in the chair. A resolution, proposed by Dr.D. Gray, seconded by Dr. J. S. Morrow, and supported byvarious members, was passed unanimously : "That everypublic health authority should have the right to examineand inspect the source of supply of any article of food offeredfor sale or consumed within its area."