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lungs are emphysematous; and the bullae are larger(sometimes very large) and either solitary or

few in number. Subpleural bullae are formed

by rupture of the subserous connective tissue layerin areas where the lung tissue is fibrotic, poorlydeveloped, or of lowered resistance. Fibrosis appearsto be by far the commonest cause ; it may originallyhave been of tuberculous origin, but signs of tuber-culosis have disappeared and the fibrous tissue is

unspecific in structure. Though it is sometimes

possible to detect the bullae in a radiogram, theyare by no means always visible. Thoracoscopy,according to Castex and Mazzei, offers valuable

diagnostic aid, and they describe in detail, with thehelp of beautiful coloured plates, the appearancesthey regard as characteristic. The formation as wellas the ultimate rupture of subpleural bullse is thoughtto be related to exertion (e.g., coughing or musculareffort). As regards the clinical features, benign spon-taneous pneumothorax was found to affect young,apparently healthy people, chiefly males ; it lasts,for about a month, and ends in complete recovery,though it may recur with the rupture of anotherbulla; it is not associated with fever or other signsof toxic absorption, and pleural effusion is absentor slight; the lungs and pleurae show no radiologicalalterations pointing to tuberculosis. Castex andMazzei suggest that such a clinical picture is usuallybest designated " pneumothorax of scarred lung."

INCIDENCE OF JUVENILE RHEUMATISM

THE incidence and manifestations of rheumaticinfections in childhood vary in different parts of theworld, and rheumatic fever is said to be rare amongchildren in tropical countries. Nevertheless theexperiment of transporting rheumatic children fromthe northern parts of the United States to a sub-tropical climate in Florida has not been an unqualifiedsuccess 1; hsemolytic streptococcal infections appearto be less severe in Florida than in Boston, butthere were relapses and recurrences of rheumatismwhen the children were living in the south. Writingfrom another part of the globe Maddox 2 estimatesthe incidence of rheumatic heart disease in NewSouth Wales as between 0’3 and 0-6 per cent.of the whole population-an incidence certainlylower than that in this country or in North America.He could find no definite relationship to known dampareas, either damp ground or poorly drained areas.The disease is seen more often on the table-lands and

slopes than in the coastal areas ; except that a highincidence was observed in the neighbourhood of salt-water lagoons. Examination of the distribution of

acute rheumatism in Sydney showed that most of thepatients came from the poorer industrial quartersof the city. Boyd Graham 3 finds that in Victoria,on the other hand, more cases arise in the middlegroup of hospital out-patients than in the poorestor the best-off groups. The economic position ofall children attending the Children’s Hospital,Melbourne, as out-patients was classified as : lowestclass 67 per cent., middle class 20 per cent., andbetter class 13 per cent., whereas for 167 rheumaticchildren the respective distribution was about 25, 50,and 25 per cent. Similar observations have some-times been made in this country (see p. 1196) and theexplanation has been offered that the children of thevery poor, with their overcrowding, keep a good dealwarmer than children who live in roomier but chillierhouses. In Bristol, a city justly famous for research

1 J. Amer. med. Ass. Oct. 16th, 1937, p. 1308.2 Maddox, K., Med. J. Aust. 1937, 1, 394, 425, 464.3 Graham, H. B., Ibid, p. 944.

on this subject, Bruce Perry and Fraser Roberts 4have been studying the variability in the incidenceof rheumatic heart disease, and find a statisticallysignificant association between the density of personsper room in the various city wards and the incidenceof rheumatic heart disease. The most obvious reasonwould be that close association favours dropletinfection, but a control investigation showed no

significant association between overcrowding andscarlet fever.

DENTAL BENEFIT FOR THE ADOLESCENT

OPENING the thirty-third session of the DentalBoard of the United Kingdom on Nov. l0th SirFrancis Acland remarked that the gap in the publicprovision of dental treatment between the attainmentof school leaving age and the acquisition of a titleto dental benefit would be much reduced by thenew provisions for adolescent insurance. At present,he said, a boy or girl who has become a member ofan approved society at any time during 1937 will beineligible for dental benefit until 1940, the normalwaiting period being about 21 years ; but when theBill comes into effect, as it should, in the New Yearthe waiting period would begin to run from the dateof entry into juvenile membership at any time afterthe age of 14 had been reached. Sir Francis has longadvocated the abolition of the gap in providingproper care of the teeth for anyone entering employ-ment after leaving school. The best dental care

given by school dentists may lose its effect if thereis an interval during which an adolescent can receiveno assistance in keeping his teeth in good condition.Sir Francis himself would like dental treatment tobe coterminous with entry into employment. Unfor-tunately the time had not yet come for convertingdental care as an additional benefit into a benefit towhich all insured persons are entitled.

OPIUM: PROPOSED LIMITATION OF RAW

MATERIAL

MUCH valuable information about the licit andillicit traffic in opium and narcotic drugs was fur-nished at the eighteenth session of the Assembly ofthe League of Nations, which terminated on Oct. 6th.The annual average world needs for legitimatepurposes of morphine is now accepted as being29 tons, of heroin one ton, and of cocaine4 tons ; these quantities are insignificant comparedwith the extent of illicit manufacture and world-wide distribution, notably in the Far East. The

Assembly called attention to the failure of some

thirty States, which had signed the Convention of1936 directed to repression of illicit traffic, to deposittheir ratifications. The Convention was framed withthe idea that it would be concluded and ratified asa matter of urgency, since its provisions offered, incertain cases, the only effective means of proceedingagainst traffickers and thus filled an important gapin existing international legislation. While China hasbeen aiming at complete suppression by 1940 theseizures by Chinese authorities in 1936 amounted to167 tons of raw opium, half a ton of heroin, a quarterof a ton of crude morphine, a quarter of a ton ofmorphine, and 7! tons of red and white pills. TheAssembly again repeated its earnest appeal to Japanto take effective measures, without delay, to stopthe clandestine manufacture and traffic carried onby Japanese subjects in China. The need for limitingthe production of raw material without which the

4 Perry, C. B., and Roberts, J. A. F., Brit. med. J. August 28th,1937, Suppl. p. 154.