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for a couple of lines in the fourth schedule thereis no mention of dental treatment in the NationalHealth Insurance Acts, and the new dental organisa-tion has at present no statutory sanction, but is basedon an agreement between representatives of the dentalprofession and the approved societies. The fact thatthe Ministry of Health, on the invitation of the DentalBenefit Joint Committee, has actually assumed

responsibility for the appointment and control ofthe regional dental officers seems to indicate thatopposition to the new scale of fees shown by certainapproved societies is not taken very seriously. Figuresavailable for December of last year show thatapproved societies representing 73 per cent. of memberseligible for dental benefit at once accepted the feesand conditions of service agreed upon by the DentalBenefit Joint Committee. The societies whichdefinitely refused to accept the scale represented onlya per cent. of eligible insured persons, and the generalrefusal of the dental profession to give dental treat-ment on any lower scale, and other considerations,have since resulted in the great majority of thedoubtful societies coming into the agreement. Itmay be taken, therefore, that the initial difficultiesof the scheme have been practically overcome, andthat a four years’ experiment in dental treatmenthas been launched. Whether a scheme involving theannual expenditure of over £2,000,000 and theprofessional treatment of over 10,000,000 insuredpersons ought to be left without some statutorycontrol, by regulations which will have the force oflaw, is a matter for serious consideration.

DIET AND CANCER.

THE idea that diet is an important ætiologicalfactor in cancer seems to make a strong appeal tothe imagination of many writers. We cannot callit an appeal to the scientific imagination becausethere is little scientific about it. It is not basedeither on considerations of the pathology of thedisease or on trustworthy clinical, experimental orstatistical evidence. The argument begins as a rulewith the assertion that cancer is rare in some

particular community. The native races of CentralAfrica or the Esquimaux are most frequently quotedin support of the contention. Since there are novital statistics available in communities such as

these, the statement at once puts out of court thoseinconvenient fellows, the statisticians, and makes itdiflicult to find anybody who from personal experiencemight be able to contradict the statement. So theperson who makes a statement of that kind isfairly sure of getting a good innings as a "cancerexpert" until the statement is investigated and foundto be either untrustworthy or incorrect. Even if itwere found to be true that certain races have alow incidence of cancer it would not necessarily-follow that this is due to dietetic factors, sinceobservations on animals have shown that racialdifferences are responsible for differences in thesusceptibility to malignancy.

It would be a reasonable argument to suggestthat dietetic errors may be responsible for cancerof the digestive tract. It is quite feasible that sucherrors might produce a type of chronic irritationcorresponding to that produced by tar, which leadsto cancer of the skin to which it is applied. Thereis at present no evidence in support of a view ofthis kind. A recent statistical inquiry by Dr. M.Young on the incidence of cancer in men of differentsocial classes has brought to light the interestingfact that cancer of the bowel is more prevalent inmen of the best social classes, while cancer of theœsophagus and stomach is higher in men of thelowest social classes. If we assurne for the sake ufargument that dietetic errors are responsible forcancer of the digestive tract, we would have toconclude that the dietetic errors committed by men

1 Journal of Hygiene, 1926, xxv., 209.

of the highest social classes must be debited with theinduction of cancer in the bowel and credited withan increased resistance to cancer of the stomach, andvice versa for the dietetic errors committed by menof the lowest social classes. Dr. Young’s analysis,therefore, yields no evidence in support of the viewthat the general susceptibility to cancer of the digestivetract is affected by such dietetic differences as existbetween men of the highest and the lowest socialclasses.But those who are trying to establish a relation

between diet and cancer do not restrict their con-

tentions to argument of this kind ; they hold that acarcinoma of the stomach, of the breast, a sarcomaof the bone, and a glioma of the brain may allfind their origin in diet. The report on Dietand Cancer by Dr. S. Monckton Copeman andProf. Major Greenwood just published by the Ministryof Health, which we review in detail in anothercolumn, contributes further evidence against theview of an essential relationship between the genesisof cancer and diet. In this case the incidenceof cancer in enclosed monastic orders living on

a vegetarian diet shows no significant differencefrom the incidence in the general population, althougha very definite assertion to the contrary had beenmade. The name of Prof. Greenwood is a guaranteeof the soundness of the statistical argumentation.For many years Dr. Copeman has been before thepublic as an out-spoken believer in the importance ofdiet in cancer. At a meeting of the British Associationfour years ago he created a sensation in the dailypress-if not among the scientific public-by suggest-ing that a definite relationship existed betweendiet (especially its content in vitamin A) and cancer.lie has treated patients suffering from cancer witha special diet. It is therefore of real significance tofind under his signature the following statementwhich occurs in the tinal paragraph of the conclusions :" We think a perusal of our report will convince mostimpartial persons that no scientific value whateverattaches to assertions supported merely by thevague pseudo-statistical evidence customarily citedrespecting the rôles of certain articles of commonconsumption in the genesis of cancer." The authors.however, propose to investigate further the apparentdiscrepancy noted by the late Dr. Charles Cioringbetween the incidence of cancer in the prison and

the general population.

COD-LIVER OIL AND VITAMIN B.

Two papers recently published,l by Erik Agduhrand Axel IIojer, have again brought into proniinence.the ill-effects of an excess of cod-liver oil in the diet.These authors find that, besides other changes, theheart is chiefly affected and that it shows brownatrophy and vacuolar degeneration of the muscle-cells. Agduhr concludes that these changes are

caused by some injurious substance in the cod-liveroil, but Hojer records experiments on rats provingthat they are produced, not by a poison in the oil,but by giving it in overdose without simultaneouslyincreasing the amount of vitamin B in the food.The ill-effect of.large doses of cod-liver oil was firstobserved in 1922 by R. H. A. Plimmer and Rosedale 2during experiments with chicks, when it was found thatthe harmful action was removed bv an increase ofmarmite (which contains vitamin B) in the food.The same workers 3 have since studied in detail therelation of vitamin B to the quantity of food andhave indicated that the quantity of vitamin B inthe food must bear a constant ratio to the quantityof carbohydrate, fat, and protein in the diet. Theyconsider it impossible to speak of the requirement ofvitamin B in terms of a daily dose as is usuallysupposed. It has also been pointed out by Plimmerand Rosedale -1 that deficiency of vitamin B must

1 Acta Pædiatrica, vol. vi., Fasc. 2.2 Biochem. Journal, xvi., 11.

3 Proc. Roy. Soc. Med., 1926, vol. xix., Sec. Comp. Med., p. 21.4 Ibid.

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be considered in two different ways, depending uponits degree. They state that if the deficiency is complete,or nearly so, the symptoms of beri-beri result more orless rapidly and end fatally ; if, however, the deficiencyis only small the typical symptoms of beri-beri donot appear, but in a shorter or longer time there aresigns of gastro-intestinal disturbance, appendicitis,and cardiac troubles, which become chronic andmay end in death. If these results be accepted itbecomes of great importance to know if the ordinarydaily diet contains an adequate quantity of vitamin B.Various foods are being tested by Plimmer andRosedale, and their preliminary data suggest that atleast half the daily diet must consist of wholemealflour or whole cereal or pulses, to avoid symptomsfrom the heart or gastro-intestinal tract. They statethat the everyday diet, consisting mainly of whiteflour, sugar, fat, and meat, does not contain an amplesupply of vitamin B and they consider it very likelythat the cardiac disorders, constipation, and gastro-intestinal symptoms nowadavs so common are

produced by a deficiency of vitamin B in the dailyfood.

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ANÆSTHETIC FATALITIES AND STATISTICS.

THE two contributions relating to anaesthetics(published on the opening page of this issue andp. 173 respectively) give food for serious speculation.In some respects they are so contradictory. The

very fact that there should be a Post-graduate lectureon anaesthetics is in opposition to Dr. GoodmanLevy’s affirmative that " little or nothing has beeneffected in the way of reducing the general liabilityto death under anaesthetics." It is generally admittedthat as regards the safety of anaesthetic administrationthere is no other factor which rivals in effect the know-ledge and experience of the anaesthetist. This mustdepend to a great extent on his education in the matter,and there has been much advance in education ofrecent years. Every student nowadays is obliged toacquire a certain amount of training in anaestheticsbefore he can be correctly signed up for his finalexaminations, and those who proceed to hold residentappointments generally acquire a really useful amountof practical experience in the giving of anaesthetics.It is quite true that the number of anaesthetic fatalitiesper annum remains a formidable figure. We have,however, no considerable evidence, supplied by Dr. Levy or elsewhere, that it does not represent afalling proportion when compared with the totalnumber of operations performed. This increasesconstantly and so, moreover, does the magnitude ofthe operations-which can be easily judged by aninspection of the daily list of operations at a few leadinghospitals. Whereas in the past these lists wouldhave been found to present a large proportion of

operations for hernia, varicose veins, and similarcomparatively trivial proceedings, to-day they includemore generally major abdominal operations andextensive proceedings for the eradication of malignantdisease. An increase in the whole number of operationsperformed, and a notable increase in the severity ofthese operations, might lead to an increased actualmortality without there being any proportionalincrease, and without there being any blameworthydefects in the anaestlesia. Much greater operativerisks, in fact, are probably run to-day than wereever ventured on by surgeons in the past. Theyare often rewarded by life-saving, but they are paidfor by an increased operative mortality. We areaware that this argument does not meet Dr. Levy’saffirmation that many of the deaths that are recordedas occurring under ether were in connexion withtrivial operations. No mention, however, is made of thestate of the patients at the time. Obviously, even atrivial operation may be an extremely serious affairwhere the subject of it is in a critical condition fromsome disorder, very likely unconnected with that forwhich he is undergoing operation. It is hard tobelieve—certainly our own observation gives no supportto the idea--that there are frequent deaths from theadministration of ether to individuals in ordinary

health undergoing trivial operations. Dr. Levybegs the question by suggesting that the deathsrecorded as arising under ether anæsthesia reallyoccurred owing to the use of some other anaesthetic.In this way, of course, it would be easy to explainaway the entire collection of statistics on which hisremarks are based. If when ether is mentioned thetruth is that chloroform was used, why should it notbe true that when the death certificate describes apatient’s heart as

"

normal," it was actually the seatof myocardial degeneration ? Nevertheless, we havemuch sympathv with Dr. Levy’s attempt to explain anapparently extraordinary figure. Generally speaking,the increased number of deaths under ether is, ofcourse, due to the enormously increased use of thisdrug as a routine anaesthetic agent in the place ofthe chloroform or the " mixture " of the past. It isprobably true that some deaths after prolonged etherinhalation arise from an excessive administration,owing to an unsuspecting belief in the completeinnocuousness of ether. It should be realised thatether is toxic and can be lethal, even though itis not easy to bring about death on the table in thecase of healthy subjects. Conditioned by considera-tions of this kind the trust in ether is justifiable, andwill not, we hope, be shaken.

IMMUNITY IN SYPHILIS.

AN annotation in THE LANCET last week (p. 145tdescribed some experiments on superinfectiun withsyphilis, and it may be of interest to recall somerecent observations on immunity to this disease.John Hunter (1810) showed experimentally that-when the skin of a person with manifest generalisedsyphilis is scarified and inoculated with material froma secondary syplulitic lesion no lesion is produced atthe site of scarification. This demonstration in vivowas the earliest experimental evidence of acquiredresistance to syphilis. Dr. Alan M. Chesney 1 hasrecently reviewed the recorded observations andexperiments of the workers in many countries whohave, since Hunter, attempted to solve the problemof immunity in syphilis. Dr. Chesney’s own experi-mental studies of this subject are not the least note-worthy among them. His critical analysis of theprotocols of experiments and the conclusions basedthereon is a valuable contribution to syphilology.He finds that all the reinoculation experiments carriedout upon syphilitic human beings, monkeys and rabbits,since the discovery of Spirochœta pallida, show thatthe host gradually acquires a resistance, more or lessincomplete, toward a second infection with the sameparasite if the disease be allowed to develop untreated.This resistant state is already present before theprimary lesion has healed and it lasts for the restof the host’s life, though subject to periodical fluctua-tions. Not all tissues of the body, however, shareequally in this resistance, and in rabbits it is moreeffective against homologous than heterologous strainsof spirochaete. The passage of time appears to beessential for the acquisition of this resistant state.Neisser’s experiments on monkeys led him to thebelief that acquired immunity in syphilis depends-upon foci of syphilis somewhere in the body. Analysisof his experiments in the light of experimental resultsin the rabbit indicates rather that in syphilis animmunity may develop which is not dependent uponthe persistence of foci of infection, and this is inharmony with clinical experience of reinfections inman. This phase of the problem is still open to solu-tion. Yet there is evidence that during the course ofa syphilitic infection the host acquires some resistanceagainst a second infection with the same species ofparasite, which may persist after the first infectionhas been reduced by treatment to the level where itcannot be detected. Reinoculation tests in animalsand reinfections in man have, therefore, no real

1 Medicine : Analytical Reviews of General Medicine, Neurologyand Pediatrics, vol. v., No. 4. Obtainable in Great Britainfrom Messrs. Baillière, Tindall and Cox, 7, Henrietta-street,London.