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backed by a better educational tradition and strongerparental support, and because they came from morecomfortable homes where it was easier to work, andhad parents who could afford to forgo their possibleearnings, they did better than children from othergroups. Today, working-class children predominatein the modern schools, while middle-class children

predominate in the grammar schools ; and accordingto another study 25 this uneven distribution cannot beattributed solely to the intelligence of the childrenbut is partly the result of social forces. Nearly two-thirds of the working-class children in grammarschools come from small families, and only just over athird come from families with 3 or more children ;in the modern schools these proportions are reversed.Moreover, the interest of parents in their children’seducation, and their ambition for them, is inverselycorrelated with family size.An inquiry in one county showed that preference

for a grammar-school education for children fell asthe social scale declined, but not as far as might beconvenient from the administrative point of view.Thus the group with the lowest proportion wantinga grammar-school education for their children was43-4%, and these were the unskilled workers. - This

group also contained the highest proportion wantinga modern-school education, but the figure was only23-9%. There is thus a widespread feeling that thegrammar-school education is preferable to any other,and a corresponding idea among many parents thata modern-school education is a catastrophe and

disgrace. Yet over two-thirds of the unskilled workerparents preferring the grammar school did not wanttheir children to stay there after 16. The aspirationsof parents of grammar-school children thus range froma steady job with good prospects when he leaves at16 to a university and a professional career. Such

widely differing ambitions make it difficult to achievea homogeneous atmosphere in the school. Of asample of working-class parents asked what occupa-tion they would like their sons to enter, over a fifthchose a profession, but the commonest choice (wellover a third) was for a skilled trade. Only about 8%favoured a clerical job, and here parents and sonswere at one ; for though the girls leaving a schoolin Lancashire put office work as their first choice, theboys put it at the top of the list of jobs they mostdefinitely rejected. This is perhaps rather cheering,suggesting a return of the craftsman in a new

guise.One troublesome thing is that working-class boys

in grammar schools are apt to have high expectationsof rising in the world, and may overrate their chances ;whereas middle-class boys in modern schools expectto fall below the position of their parents. In fact thewhole notion of three types of school, all of equalstatus, has already proved to be untenable. For thefact remains, as Professor MARSHALL puts it, that" some children are more able than others, that some

forms of education are higher than others, and thatsome occupations demand qualities that are rarer

than others and need longer and more skilled

training to come to full maturity, and that theywill therefore probably continue to enjoy highersocial prestige."25. Halsey, A. H., Gardner, L. Brit. J. Sociol. March, 1953, p. 60.

He concludes that competitive selection must

remain with us to a considerable extent, but arguesstrongly for " courses of secondary education " ratherthan " types of secondary schools." For a systemwhich sorts the children out by general ability, andthen passes them through watertight schools to appro.priate grades of employment is going to emphasisedifferences between occupational groups, as well asthe correlation between social class and type of school.We shall, in fact, be in danger of grooming childrenfor a governing class-the

" unified elite" describedas the characteristic feature of a totalitarian societv.We, as a democracy, like to draw our leaders fromall sorts of conditions of men, who by their outstandingability have climbed ladders other than the educationalone ; and it is important, Professor MARSHALL says, topreserve these other ladders. Education can never beidentified with an educational label ; and he stigma-tises as"’ a pernicious thing " the snobbery of such alabel, certificate, or degree-the prestige of a titleoften bearing " little or no relation to the value of thecontent." From some of the dooms he foresees we areat present protected by competitive selection ratherthan allocation ; but others are already operating.For an ambitious youth an education at a modernschool may easily prove a more awkward possessioneven than a shorter birth-certificate. ProfessorMARSHALL has done his best to put us on our guard-and on our mettle.

1. Madwar, S., Zahar, A. R. Bull. World Hlth Org. 1953, 8, 513.2. Mer, G. G. Ibid, p. 521.3. Chow, C. Y., Thevasagayam, E. S. Ibid, p. 491.

Annotations

ATTACK ON FLIES

WE are encouraged in our belief that the world is

growing up by the almost universal acceptance of theidea that a modicum of fundamental knowledge isneeded for the solution of even the most everydaybiological questions. Somewhat later than the sportsman,the hygienist has learned that if you wish to destroyan animal you must have some knowledge of its habits.The fly-swatter was a sporting weapon and the stickyflypaper a low poaching dodge, but both were abandonedlong ago by the professional muscicide. Some paperspublished lately by the World Health Organisationcontain several elegant illustrations of modern techniquein fly control.

In Egypt it was found that it is an outdoor tempera-ture of over about 75°F which drives the flies indoors;when it is cooler they prefer to frolic in the sun.1 Wewish we could turn this promising observation to ourown advantage in this country, but unfortunately welack the necessary local knowledge. In houses inPalestine which are sprayed regularly with D.D.T. themajority of the flies are now resistant to this compound.Nevertheless, they do not choose to sit on the walls andceiling but prefer the doors and windows and, above all,the furniture.2 The identification of the favourite

resting-ground of a fly is no academic whimsy but avaluable guide in the use of costly insecticides ; it isdifficult in this country to realise how much moneymight with advantage be spent on insecticides in warmerclimates. The trouble is that no-one cares to have hisfurniture coated with insecticides in a kerosene base,and another suggestion, this one from Ceylon, deservesfurther exploration.3 It has been known for years that

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for reasons which are quite obscure a fly likes to sit upona grid-like surface. The exclusion of flies from a tent

by means of one-inch fish netting, a simple conjuringtrick to the inexperienced, is probably an exampleof this. A cheap and efficient fly-trap can be madefrom a wooden rectangular frame laced, after the fashionof an Indian charpoy, with string impregnated withinsecticide. Trials in hospital wards and kitchens, notfar from a prolific breeding-ground of flies, showednot only a most encouraging kill under each frame butan appreciable reduction in the active airborne popula-tion. This method is worth a trial in our own kitchensand it must not be thought that research on these

questions is limited to warmer climates. The report 4for 1952 of the Pest Infestation Laboratory mentionsthe finding of house-flies which were more resistant thannormal in a shop regularly sprayed with D.D.T. A

change to gammabenzene (B.n.c.) put an immediateend to their intransigence and there seems no risk of thewidespread emergence of a resistant strain. To the

hygienist, the laboratory’s observations on blowfliesare more interesting. Refuse dumps are only too

commonly infested with these beastly creatures and,by marking them with a phosphorus tracer, they havebeen shown capable of migration for several miles.Control by the intelligent use of D.D.T. is not expensivebut it has resulted in the. appearance of some resistantstrains. That Clostridium welchii was found in evervbatch of blowflies examined need cause little alarm.If looked for with diligence, this organism is almostomnipresent in dirt and it is easy to exaggerate the risksof food-poisoning from this cause. But blowflies are

nasty things and better dead. ,

Three years ago we gave some reasons for thinkingthat the importance of flies in the transmission ofinfectious disease in this country might have receivedtoo much notices Their guilt is repeated in almostevery textbook with little regard for the weakness ofthe case for the prosecution. They irritate us when

they sit on the back of our neck and they disgust uswhen they stroll on our food, but may not this be justsuch an irrational loathing as all men (with some

eccentric exceptions) feel for serpents ’? Flies havenoisome habits and dirty feet ; we see them plain andwe hate them : igitur, they are a common cause ofinfectious illness. But their guilt is still open to doubtand deserves re-examination by modern methods.

Moreover, their r6le of scapegoat is liable to withdrawattention from some other more dangerous and moreeasilv controlled source of infection. The medicalofficer of health for the city of Oxford has lately madea welcome plea for more elasticity in our thinking onpreventive medicine and for a greater willingness todiscard those procedures which have the sanction oftradition alone. 6 Nevertheless, we hesitate to suggestthat anyone, even in England, should relax his effortsto destroy all the flies he can. We do not know that

they can spread infection but we are not sure that theycannot. There are occasions and places where thematter might be tackled with more intelligence andingenuity. It is not easy and it is sometimes hazardousto reduce these biological problems to rule of thumb,and there is no better illustration of this than the naturaldevelopment of resistance to lethal agents by insectsand bacteria. Local authorities, faced by questionsof this kind, will rarely have among their staffanyone with the necessary academic training in biologyand they would do well to make use of the availableconsultant services,- such as the Pest InfestationLaboratory.

4. Pest Infestation Research Board Report for 1952. H.M.Stationery Office, 1953.

5. Lancet, 1950, ii, 864.6. Warin, J. F. J. R. sanit. Inst. 1953, 73, 309.

NOSE AND HAND IN RESPIRATORY INFECTION

WE have heard much in the last twenty years of thetransmission of hæmolytic streptococci through dropletsand droplet-nuclei and through dust in the air of hospitalwards ; and bacteriologists have shown that oiling thebedclothes and floors of wards reduces by 75-90%airborne dust particles carrying bacteria. But there islittle direct evidence that such measures effectivelyreduce the incidence of streptococcal disease, and no-onenow seems very enthusiastic about trying to overcomethe diulculties entailed in putting these measures intopractice on a large scale. The emphasis now seems to beshifting in the direction indicated by Hamburger and hiscolleagues 1 when they showed the danger of nasal carrierscontaminating their environment, the importance of thehands in transferring hæmolytic streptococci fromthe nose to the environment, and by contrast the

poor bacterial yields from droplet-spray during forcedexpiratory exercises. An experimental study by Rubboand Bemjamim,2 of Melbourne, with healthy carriers ofhæmolytic streptococci, and with persons carrying a

marker organism in their upper respiratory passages,supports these findings. Rubbo and Benjamin foundthat only 18% and 55% of the carriers expelled detectablehæmolytic streptococci during violent coughing at targetplates held 12 inches and 6 inches respectively from themouth ; even then the average count was only onecolony per cough per target plate. Unless a carrier had a

good flow of saliva (2-3 ml. per min.) containing a highconcentration of organisms (> 105 per ml.) he was unlikelyto be an effective expeller of droplets or droplet-nuclei.Few carriers were found to measure up to these require-ments. Droplets and droplet-nuclei are therefore

relatively unimportant in transmission of this infection,because of their extremely low content of hæmolyticstreptococci. By means of a slit air sampler and anelectrostatic air sampler, Rubbo and Benjamin alsoshowed that groups of 30 schoolboys entering or leavinga schoolroom or vigorously singing did not contaminatethe atmosphere with hemolytic streptococci anythinglike as much as did gentle shaking of their handkerchiefsfor one minute. Dust particles produced by shakinghandkerchiefs polluted the air more effectively thanviolent expiratory activities ; but it was contaminationof hands and clothing from a heavily infected nose thatwas the principal cause of contamination of the environ-ment and of transmission of the infection to other

persons.These experiments make clearer the relative importance

of the various pathways of transmission of hsemolyticstreptococci, and probably also of other respiratorypathogens. The formidable task remains of devisingeffective and practical means of breaking down the chainof infection from nose to hands or to handkerchiefs andclothing, and thence by hands or dust to the nose ormouth of the next victim. But at least we know whereour main efforts should be concentrated, and can haveincreased confidence in advising the public to wash theirhands.

1. Hamburger, M. jun., Green, M. J., Hamburger, V. G. J. infect.Dis. 1945, 77, 68, 96 ; Ibid, 1946, 79, 33.

2. Rubbo, S. D., Benjamin, M. J. Hyg., Camb. 1953, 51, 278.3. Chiari, H. Beitr. path. Anat. 1889, 5, 329.4. Stibbe, E. P. J. Anat., Lond. 1929, 64, 62.

RESPIRATORY DIVERTICULA

DIVERTICULA of the respiratory tract are by no meansrare. In the trachea three types are found. The first typeconsists of short cylindrical structures, always on theright side; they contain cartilage in their walls and are --probably rudimentary bronchi.3 4 Those of the secondtype are broader protrusions between the transversemuscle bands that unite the posterior ends of the trachealcartilages. (The "aerial goitres" in women after childbirth