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this epidemic unscathed, and some estates which hadrecently initiated oiling showed remarkable improve-ments in health during this severe and testing epidemicyear. And the statement that the " whole labourforce on estates in Malaya was seriously infectedthroughout the whole Peninsula," is contradicted bythe report of the Malaria Advisory Board, F.M.S.,for the year 1926.That there has been no " complete breakdown " in

oiling, or that it is a discredited measure, in Malayais borne out by the report of the Malaria AdvisoryBoard of the F.M.S. for the year 1930, which states(par. 10) that the chief health officer issued, throughthe Planters’ Association of Malaya, the followingnotice :-

" The Malaria Advisory Board invites the attention of allestate managers to the vital importance of maintaininganti-malarial oiling, draining, ditching, and fflling, &c., on

their estates during this time of economic stress. Loss oflabour from sickness and death will inevitably result onestates where anti-malarial works are neglected. The Boardalso desires to draw attention to the fact that labour lineswhich may be closed down owing to the present depressedstate of the rubber industry should not be reopened untilanti-malarial measures on the estates have been carried outvery thoroughly for at least three weeks prior to the datewhen new labour is to be engaged."The year 1926 conclusively proved that for

A. maculatus in Malaya the half-mile radius issufficient. We already knew it was enough forA. umbrosus and A. ludlowi. And it is the officiallyaccepted area to-day throughout Malaya, as may beseen in the section of the Straits Settlements annualreport for 1930 (p. 15), dealing with the rural area ofSingapore Island. Further, in spite of ColonelClemesha’s claim that where in India " A. culicifaciesis the main carrier, we cannot lay down any suchdistance," there are reasons to believe that the samedistance is sufficient. As long ago as 1902 the seventhreport of the Malaria Commissioners of the RoyalSociety states that " where breeding-grounds are halfa mile distant and have not recently existed closer,malaria is reduced to a minimum, and anopheles arenot to be found in the houses." Since then many otherobservations have been made in India to confirm theseconclusions which were based on extensive and accu-rate researches detailed in the Commissioners’ reports.Colonel Clemesha evidently confuses the distance

mosquitoes can fly from their breeding-places with themuch shorter distance they can keep up endemicmalaria, a distinction of vital importance in thepractice of anti-malarial work.

In spite of his " considerable mathematical educa-tion " he thinks that it is necessary to " do away with100 per cent. of anopheles " if the spread of malariais to be stopped in an area. He says this is " impos-sible of realisation." Therefore, he argues, you mustemploy some other measure, for if you do not theresults will be "much too slow for the commercialworld." This is incorrect. Sir Ronald Ross, the lateProf. Carl Pearson, and others, showed mathematicallythat it is not necessary to get rid of 100 per cent. ofanopheles in order to get rid of malaria. And thework in the Malay Peninsula and elsewhere has provedthis practically. The work in Malaya was done in acountry described by the High Commissioner (in anaddress to the Federal Council, F.M.S., on Nov. 16th,1927) as " by far the most malarious country " whichhe has been in during his long and wide administrativecareer in the West Indies, West Africa, Ceylon, andMalaya. He said the development of the country" would have been totally impossible unless thedanger of malarial infection had first been successfullycombated." And he added that the " record of theAmerican engineers and physicians at Panama sinks,

in my judgment, into complete insignificance whencompared with the practical achievements which havebeen effected during the last decade and a half in theMalay Peninsula." Surely, not an inconsiderableachievement for a people who knew not the term" anti-gamete campaign," evidently not " much tooslow for the economic world," and a conclusive answerto Colonel Clemesha’s " pure mathematics."

I am, Sir, yours faithfully,MALCOLM WATSON.

The Ross Institute, Putney Heath, London, S.W.,August 15the,1932.

MALCOLM WATSON.

PYREXIA IN GENERAL PARALYSIS OF THE

INSANETo the Editor of THE LANCET

SIR,—In the leading article in your issue ofAugust 20th we were quoted as saying that weregarded sulphur therapy in the psychosis as beinglargely, if not entirely, psychological in its effects.In case of possible misunderstanding we would liketo state that when putting forward this hypothesis(THE LANCET, July 30th, p. 237) we were confiningour remarks strictly to the psychoses under discussion-namely, schizophrenia and manic-depressivepsychosis. The effect of sulphur therapy is entirelydifferent in general paresis, for here we are dealingwith an organismal disease, and there seems to beno room for doubt that in this particular psychosisthe sulphur therapy, like other pyrexial treatments,brings about its results by its action on the spirochætesand the pathological changes which have resultedtherefrom. That this appeared evident is our

excuse for not having stated it explicitly in our paper.We are, Sir, yours faithfully,

P. K. MCCOWAN,M. L. M. NORTHCOTE.

Cardiff City Mental Hospital, August 22nd, 1932.

P. K. MCCOWAN,M. L. M. NORTHCOTE.

THE NATURAL ENEMIES OF THE BED-BUG

To the Editor of THE LANCETSIR,—The note in THE LANCET for August 13th

(p. 376) draws attention to a public health problemwhich has not yet, I believe, been satisfactorilysolved-viz., the best way to combat the bed-bugpest. I have recently been studying this subject, andI have been surprised at our lack of practical knowledge(I speak for myself at any rate) on this importantmatter. Incidentally, I can testify to the value ofthe pamphlet, referred to in your note, by Major E. E.Austen ; but the complete lack of uniformity in thepractice of different health departments as regardsdisinfestation is an indication, I think, that we donot yet know what is really the best method of

disinfesting bug-infested houses.The question what are the " natural " enemies of

the bed-bug is a very interesting aspect, but at

present it cannot be said to hold out much hope ofpractical help. Few people, I fancy, would welcomethe introduction of cockroaches, red-ants, or even ofbook-scorpions into their houses on the chance thatthey would wage war on bugs. My object in writingto you is to ask any of your readers who believe thatthey know the " best " method-i.e., from the pointof view of efficiency and practicability-of disinfestingold cottage property which is bug-infested to let asknow their experience.

I am, Sir, yours faithfully,C. KILLICK MILLARD,

Medical Officer of Health, Leicester.Health Department, Leicester, August 18th, 1932.

C. KILLICK MILLARD,Medical Officer of Health, Leicester.

Health Department, Leicester, August 18th, 1932.