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Dr. Yule refers to the " handywoman " difficulty.Not infrequently. he says, unqualified women appearto be the sole attendants at confinements, but wheninvestigation takes place there emerges " the shadowysupervision of a medical practitioner." Dr. Yule haswritten to the C.M.B. for Scotland for guidance as towhat constitutes " direction " on the part of a medicalpractitioner, but so far no light has been forthcoming.He mentions that the Royal Sanitary Institute andthe County Councils’ Association have approached theC.M.B. for England on the same point, and that theEnglish Board are of opinion that " under the directionof " means " in the presence and under the directionof " and further, that they (the English Board)intend to take the earliest opportunity of pressing foran amendment of the subsection of the Act dealingwith the matter which will remove the words" habitually and for gain "--words which render thesubsection futile at present.

Correspondence.

CANCER AND DIET.

"Audi alteram partem."

To the Editor of THE:LANCET.SIR,-Your leading article under the above title

in THE LANCET for last week obviously necessitatesa reply from me.

Needless to say, no one can regret more than I

myself the " flamboyant " and unwarranted state-ments that appeared in a certain section of the publicpress in reference to my paper in the PhysiologicalSection at the recent meeting of the British Associa-tion. And I specially regret that your criticism ofmy communication should have been based on unsatis-factory reports. Rationing in this country duringthe last year of the war was fairly stringent, in thelarge towns at any rate, this stringency having beenspecially marked as regards those foodstuffs which,as you state, provide the main part of the fat-solublevitamin A in a normal dietary. And yet, except asregards tuberculosis, there is, so far as I am aware,little evidence that the public health was adverselyaffected ; while, as indicated by the Registrar-General’s statistics, the cancer mortality for bothsexes, especially in London, was slightly thoughdefinitely diminished. In the case of the CentralEuropean States to which you allude additionalfactors came into operation.My own investigation as to the results of a dietary

deficient in the fat-soluble A factor but sufficient(and this is the important point) in every other respect,while at the same time varied and appetising incharacter, has now extended over a considerableperiod,1 and has included an experience of it in myown person lasting for nearly a couple of years.During this time I was necessarily engaged in a certainamount of physical as well as mental work. Yet itwas not until the end of that period that I experiencedany noticeable ill-effect as the result of the experiment-a skin affection of the palms of both hands whichreadily cleared up on the addition to my dietary ofuncooked vegetable food in the form of salads. AndDr. Wyard 2 reporting on our investigation at theCancer Hospital, which you quote, stated in referenceto patients on this dietary that " In no case was anyunfavourable change in the general condition of thepatient attributable to the diet, and in manyimprovement was definite, at least at first." Themedical superintendents of several infirmaries inwhich patients have also been under treatment havereported to the like effect. The suggestion that Ihave overlooked the literature of the subject, and,more particularly, the work of Prof. J. C. Drummond,is hardly borne out by the fact that in my paper I

1 Copeman, S. M.: Brit. Med. Jour., 1920, ii., 159, Dis-cussion on the Present Position of Vitamines in ClinicalMedicine. 2 Wyard, Stanley : THE LANCET, 1922, i., 840.

specifically referred to his investigations and, as

regards the growth of tumours, stated that I was ingeneral agreement with his views.The second paragraph of the article would seem

to be superfluous in view of the fact that in my paperI stated that the use of the dietary had not been foundto exert any specific differential effect on the growthof the tumour, as had originally been hoped mightprove to be the case ; and that consequently thecure of cancer was not in question, the methods beingat most palliative only. As regards this latter point,it may be noted that Dr. Wyard in the report youquote makes the statement that " general improve-ment, though slight, was in some instances definite."It may be mentioned that estimates as to probableprolongation of life in any instance have necessarilybeen based on the opinion of those in medical chargeof the patients as the outcome of their generalexperience of cases in similar condition.As regards the final paragraph, I may perhaps be

permitted to state that a few months ago I submittedto a meeting held in the laboratories of the ImperialCancer Research Fund, under the chairmanship ofDr. Murray the Director, a communication practicallyidentical in terms with my Liverpool address. Thismeeting, at which Dr. Wyard was also present,afforded opportunity for helpful criticism. Thedietary in question has been gradually evolved as theoutcome of consultations with Prof. Gowland Hopkinsand other bio-chemists ; of experiments on myself,and, with their consent, on other private individuals,and of patients in various public institutions ; as alsoof a comparative study (not yet completed) of thedietaries and vital statistics of certain " enclosed "and " unenclosed " religious communities in thiscountry and abroad.

It is, I think, unnecessary to comment on theassumption with which the article concludes.

I am, Sir, yours faithfully,

I Sept. 24th, 1923. -

S. MONCKTON COPEMAN.

PROBABILITY AND EXTRASENSORIALCHANNELS OF KNOWLEDGE.

To the Editor of THE LANCET.

SiR,—In his address on Extrasensorial Channels ofKnowledge (THE LANCET, Sept. 8th), Prof. CharlesRichet brings forward evidence which, in his opinion,establishes the truth of " knowledge of reality obtainedby other means than by the ordinary channels of thesenses." Some of this evidence is of the followingcharacter. A dreams that B, of whose movements hecan have no direct means of information, has died,and, in fact, B has died. To the retort of the man inthe street that this is a mere coincidence, Prof. Richetreplies : " Chance is, indeed, a very convenient god,to which we can always appeal. But why should weintroduce these extremely small probabilities into ourcalculations ? Practically we never come across aprobability of 1 to a 100 million, and yet this is thefigure at which one must assess the probability ofWingfield having once in the course of his life a singlehallucination, and that just the hallucination of hisbrother being killed at the same moment. Chance willevidently not explain these occurrences." I do notknow how it is possible to assess the arithmeticalvalue of the probability in Wingneld’s case, since Iha.ve no knowledge of the frequency or contents of thisgentleman’s dreams, save in one instance, but theman in the street would surely rejoin that, far fromnever coming across probabilities of 1 in 100 millions,he meets them almost every evening. The probabilitythat the dealer at bridge will distribute the 52 cardsin any assigned order is measured by a fraction whichhas more than 60 zeros after the decimal point beforewe reach a significant figure, it is the reciprocal of thecontinued product of 52 x 51 x 50, &c. Events, theprobability of which is so immensely less than Prof.Richet’s 1 in 100 millions, happen regularly whereverfour bridge players are gathered together. Evidentlythere is something wrong. The philosophy of the

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calculus of probabilities has engaged the attention ofmany eminent men and they have made such sadmistakes, according to Mr. J. M. Keyes, that it isdangerous for a mere statistician to suggest an explana-tion ; but, as the use of probabilities is very commonin medical inquiries and so distinguished a physiologistas Prof. Richet has employed that calculus, it may beof interest to play the devil’s advocate and to arguethat Prof. Richet’s treatment of his problem is whollyfallacious. The point I submit is, that in any rational application :

of the calculus of probabilities there is always expressedor implied an alternative. Thus suppose four personssit down to play bridge and the dealer receives thewhole of a particular suit. The chance that this will persons

happen is much less than one in a billion, a good dealsmaller than one in 100 millions. Suppose the fourplayers are intimate friends, they may be surprised,they may even write to the Field, but they will notsuspect the dealer of cheating. But suppose that thefour players are total strangers come together in thesmoking room of a transatlantic liner, the opponentsof the dealer who has dealt himself or partner 13 of asuit might do more than write to the Field. The pointis that the alternatives in the two cases are notdeemed to be equally probable. The probability thatan intimate friend has cheated at cards is deemed tobe very much less than 1 in a billion, but the proba-bility that a total stranger has cheated is thoughtgreater than that a particular event of this order offrequency and favourable to him has happened.

Consider the method of application of the calculusof probabilities to medical problems, usually regardedas legitimate. A persons have been attacked by adisease and treated with a particular remedy and a haverecovered, B persons similarly attacked have not beentreated and b have recovered. The fraction a/A isgreater than the fraction b/B ; is the differencesignificant ? Let us suppose, which is not alwavs true,that A and B are, apart from the giving or withholdingthe remedy, absolutely in pari materia, and that theprobability that such a difference as a/ A -b/B mightarise " by chance " can be arithmetically computed-which again is not always true-and that we find thischance to be 1 in a billion, what is the inference ? Theinference depends upon the nature of the alternative.If the remedy is such that its possible activity is notincongruent with the whole of our knowledge, we shallinfer that it is more likely that the remedy had aneffect than that an event which on the average happensonce in a billion trials has happened this time. Supposethe disease were acute intestinal obstruction and theremedy painting the left wrist with iodine : we shouldrefuse to believe that the cases were in pari materia orwe should adopt the attitude of the friendly bridgeplayers. Suppose the disease were diphtheria and theremedy antitoxin, we should unhestiatingly acceptthe alternative. Between those extreme terms lies acontinuous series of instances : the mere statement ofa probability is not and never can be sufficient ofitself, it is only great or small in relation to somethingelse. That is, of course, the argument of Hume-statedbefore his time by Locke, who said, " It is harderto believe that God should alter or put out of itsordinary course some phenomenon of the great worldfor once, and make things act contrary to theirordinary rule purposely, that the mind of man might Ido so always after, than that this is some fallacy or Inatural effect of which he knows not the cause, let itlook ever so strange."

I need not use space to point out the application ofthese considerations to Prof. Richet’s thesis, but thosewho are interested in the particular class of investiga-tions to which he refers will find a very instructivediscussion of the application to them of the calculusof probability in Prof. Edgeworth’s notice of Prof.John Coover’s investigations. I.r OVV’lo en. ",An"11ü ’;0;’" 1,fn 11-,:,.. I

MAJOR GREENWOOD,National Institute for Medical Research,

Hampstead, N.W. 3, Sept. 21st, 1923.

1 Jour. Roy. Stat. Soc., lxxxii., 1919, 222.

A PLEA FOR THE NATIONALISATION OFOUR MENTAL HOSPITALS.

To the Editor of THE LANCET.

SlR,—It is not until quite recently that the attentionof the medical profession, and to a certain extent ofthe general public, has been at all directed to theposition of the treatment of disorders of the mind.Probably owing to their extreme complexity it hasremained more or less in the background. No attempthas been made on anything but the smallest scale toapply the same methods of investigation and treat..ment which mark other branches of medical science.As a result the insane have been merely herded togetherin public institutions really more concerned with thesafeguarding of the public than with alleviating thesufferer. Reform on these lines has merely meant amore humane segregation, with the result that scatteredall over the country we find these large buildings,for the most part admirably and economicallyadministered, where the insane are housed and fedwhile they may or may not recover. What positionthese institutions hold in the opinion of the outsidepublic is clearly shown by the fact that practicallyall admissions to them are involuntarv. Nowhere isthere yet set up a system where the early suffererwill come for advice and treatment in the same wavthat he will flock to the ordinary out-patient depart-ment of any of our large hospitals.But at last the mystery attached to the label

" mental " is gradually being solved and removed.It is recognised that for the best results cases mustbe seen in their incidence. Also that disorder of themind requires not only the specialist trained inpsychological methods, but the help of the patho-logist and the physician, in fact of every branch ofthe profession. And not only this, but equallyimportant is skilled nursing of the very highestorder. With what result ? That the treatment andstudy of mental diseases is passing to the place whereonly these advantages can be reaped-into relationwith our general hospitals and teaching centres. Forif, say, a case of cardiac disorder or a fracture turnsout badly, the patient can still carrv on undera partial disablement; but let a disorder of themind become chronic and it results in a completefailure and a permanent loss to the State. It isquite impossible and also unnecessary to alter ourpresent asylums and make them into hospitalssuitable for the reception and treatment of acutemental disorders; and equally impossible for thelarge bulk of their present medical staffs to keepthemselves abreast of modern methods. And neitheris this the most economical method. It is waste oftime, money, and personnel to employ a highlytrained staff on the nursing of idiots, dements, andthe hopelessly insane. Having regard for the treat-ment they require, we can divide our patients roughlyinto two classes : in the early stages, when evervthingthat our science can possibly do for our patient mustbe tried ; if this fails in its end and no recovery takesplace, we pass to the second, the chronic or hopelesslyinsane, requiring merely some institution where theycan be looked after as economically as possible withdue regard to their happiness, comfort, and welfare,

and where they can be employed to the best advantagewith regard to their cost of maintenance and by thismeans made the least possible burden to the State.Now arises the problem, how can early mental

disease be brought into contact with the conditionsit requires for its treatment ? It is impossible tothink that under present conditions this will evermaintain in the majority of our county or boroughasylums. Their isolated position alone is almost a barto most of them. Neither ought the matter to remainin statu quo until the country can stand the enormousexpense of building and equipping new and modernmental wards. In the meantime there is one obviousway in which the best can be done for the sufferer.It is out of the question that every case of mentaldisorder can be sent for treatment to one or other of