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to get into uniform ; in another place it said, " We arecontinually turning down applications for deferment."It only shows that the majority of the EMS do not wantto don uniform.

This unfair treatment has created a cleft in the pro-fession and it is daily growing wider. On the one handare those who have served abroad ; on the other, thosewho stayed at home.To end with here are some suggestions. (1) A radical

reorganisation of the RAMC administration. (2) Amal-gamation of neighbouring medical units, with a saving indoctors, nursing officers, and personnel. (3) Easierterms for LIAP for those who must miss release with theirgroup. This would be more appreciated than any finan-cial offer. (4) A drastic combing out and putting intouniform of the EMS doctors.CMF ONE OF THE DEPRESSED.

CURARE IN ANESTHESIA

SIR,—That curare is now to be regarded as a " safe "drug will come as a shock to some earlier workers withthat substance-or rather with those substances, forcurare has hitherto been a single name to cover a greatvariety of mixtures of poisonous alkaloids whose onecommon property has been muscular paralysis.

If anaesthetists are to be encouraged to try curare asa relaxing agent two warnings are immediately necessary.The first is that only a preparation securely testedbiologically (including, I would urge, assay on dogs)be employed. Your two contributors (July 21, pp., 7 4,75), both used the same preparation, and it would bewiser to refer to their dosage in terms of ’ Intocostrin ’rather than curare. That the dose is 0-5 mg. of curareper lb. body-weight is not a safe statement- when thereare curares in this country that differ 100 times in theirpotency.The second danger in human curarisation may not

apply to intocostrin. It is an acute and uncontrollablebronchospasm, which may cause death unless an endo-

. tracheal catheter- can quickly deliver oxygen to thelungs under considerable positive pressure.’ We aban-doned curare in 1937 because of this bronchospasm, andwe found that it could occur with the use of a compara-tively pure curarine (West, R. Lancet, 1938, i. 432 ;J. Physiol. 1938, 91. 437). Messrs. E. R. Squibb mayhave overcome this difficulty, which we inclined at thetime to attribute to the liberation of histamine (At&m,M. et al. J. Physiol. 1939, 95, 148). But I see that Dr.Griffith (p. 75) notes a " transient bronchospasm " incertain cases, and so it seems opportune to re-issue awarning of the danger which caused us to give up theattempt to use curarine and curares, not only in tetanusbut in parkinsonian, hemiplegic, and other rigiditiesin which it might have a beneficial effect (Lancet, 1936,i, 12 ; Proc. R. Soc. Med. 1932, 25, 1107).Many of us will look on the trials of intocostrin with

interest. And we should like to know a little moreabout its composition.Edinburgh. RANYARD WEST.

MOSQUITOES IN STATIC WATER-TANKS

SIR,—The static water-tanks in London and in someparts ,of the Provinces were often found to be breedinggrounds for mosquitoes, especially those tanks situatedbeneath the branches of trees, and iron tanks were morefrequently infested than conorete " basement " tanks.With a few exceptions the species of mosquito inhabitingthe static water was Culex pipiens, a non-biting variety,at least on man, but they are extremely troublesome inbedrooms on account of their annoying habit of flyingaround the heads of would-be sleepers for hours on end,presumably because they enjoy the warm moist breathof humans. This annoyance justifies control measuresbeing taken.During periodical inspections of the static water-tanks

in London it was found that tanks full to the brim wereless frequently infested than tanks not quite full, evenwhere they were similarly situated. Indeed, on manyoccasions when inspecting batteries of tanks it was foundthat where six or eight formed a battery, one or twomight contain larvae while the others were free, and inevery instance the tanks containing larvae were notfull to the brim whereas the tanks free of larvae were.

Most of the tanks have now been " emptied "-thatis, with only an inch or two of water remaining. Duringa recent inspection it was found that most of the tanks,including the concrete " basement " tanks, contain aninch or two of water and many of them are breedingmosquitoes-a higher percentage than before they were -

emptied. Therefore the tanks at the present time, sincethey were "emptied" are more suitable as breedinggrounds than they were before they were " emptied."It is assumed that most of the tanks will soon be removed,but until they are measures to prevent mosquitoesbreeding in them should be carried out. A simple,effective, and inexpensive means of control is availableand consists of sawdust soaked in oil. The sawdustshould be soaked in oil for at least 24 hours and then itcan be put into the tanks, either tied in a sand-bag ora few handfuls thrown into the tank. This could bedone even where the tanks are quite dry because itwould be there in readiness in the event of rain collecting.If these preventive measures are taken now the singleapplication would be sufficient for the remainder of thebreeding season-i.e., to the end of September.

Ministry of Health MalariaLaboratory, Epsom. P. G. SHUTE.

PNEUMOCONIOSIS OF COALMINERSSIR,—At a recent meeting of the Pathological Society

of Great Britain and Ireland it was said that a belief hasarisen in certain quarters in the coalfield that " coal " .

dust is harmless when breathed into the lungs. Theimplication is that unless there is at the same time expos-ure to rock dust, men working in a coal-dusty atmosphererun no special danger ; there is therefore no need tocontrol the concentration of dust in the air of coalmines.As the alleged basis for this belief is in the findings of theMedical Research Council’s Committee on IndustrialPulmonary Disease, and as we have been associated withthe investigation of pneumoconiosis in South Walessponsored by this committee, we should like to clarifycertain points.

In the MRC’s first report on chronic pulmonary diseasein South Wales coalminers (Special Report Series, no.243, 1942), the view is put forward that " coal " (i.e., theorganic, carbonaceous, combustible matter, as distinctfrom its contained mineral matter or ash) is probably notthe constituent of the dust breathed by the miners whichis responsible for their pneumoconiosis. Evidence waspresented to show that the siliceous matter which alwaysaccompanies the coal in the airborne dusts and in thelungs of deceased miners is more likely to prove to be thepathogenic material. High concentrations of siliceousdust were demonstrated in all the coal-containing lesionsof the lungs studied ; and it was pointed out that theirpresence is often missed because of the masking effect ofthe coal which imparts a dense black quality to the grossand microscopic appearance of the lungs.

In the latest report of this investigation (No. 3,Experimental Studies, in the press) further evidence isbrought to indicate that the coal substance itself playsonly a minor part in the production of the pulmonaryabnormalities which have formed the basis of the patho-logical- study. Chemical and mineralogical determina-tions have revealed abnormal concentrations of siliceousdust in all lungs studied, and statistical treatment of theresults "appears to indicate a positive correlation - ofseverity of disease with siliceous content rather than withcoal. And of the siliceous components of the dust,quartz and mica seem to be incrimated rather thankaolin, with the balance of evidence in favour of quartzas the most active pathogen. Animal experiments withpurified coal (i.e., coal whose ash had been reduced to aminimum-considerably less than 1%) resulted in mini-mal reactions to the dust in the lungs ; whereas airbornedusts from coalmines produced variable reactions ap-proximating in some cases to those obtained with highlysiliceous powdered strata and dusts. These positiveresponses are attributed to the siliceous matter containedin the coal dust and not to the coal substance itself. ’

These facts lead us to reaffirm the belief that it is thesiliceous matter in the inhaled coal dust which is primarilyresponsible for the pulmona,ry,abnormalities to be foundamong workers in the coal industry. Neverthelessmany facts of this complex aetiology remain obscure.Thus, while quartz is probably the most noxious con-