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necessary to give a period of treatment directedtowards the development of the musculature of thefoot.

Mr. E. LAMING EVANS (London), who followed,laid stress on the importance of focal sepsis as anaetiological factor in hallux valgus. He advocated,and practised regularly, the operation of excisionof the metatarsal head. There was no interferencewith the stability of the foot if the stump of theneck was brought to rest on the sesamoid bones.Mr. Evans regarded the post-operative re-educationof the foot musculature as an essential part of thetreatment.

Mr. D. MACRAE AITKEN (London) supported theview that the deformation began in early life andwas due to static errors. Contrary to general experi-ence he had found that the operation of cuneiformosteotomy of the neck of the first metatarsal wasfollowed by good results.

Mr. NAUGHTON DUNN (Birmingham) agreed thatit was necessary to institute a careful inquiry as tothe exact causation of the pain. He recognisedtwo main types of case : (a) Where the pain wasdue to pressure ; in these, trimming of the metatarsalhead was sufficient. (b) Pain due to joint movementonly. Here he practised excision of the metatarsalhead, or of the base of the phalanx, according tothe age of the patient.The PRESIDENT expressed his belief that com-

pression of the forefoot in improper shoes wasthe outstanding factor in the aetiology of halluxvalgus and rigidus. Re-education of the smallerfoot muscles was therefore an integral part ofall treatment. In the choice of an appropriateoperation, every case had to be judged on its merits.In his experience the best results had followed com-plete excision of the metatarsal head, or in lesssevere cases, trimming of the head. After thisoperation the foot should always be strapped so asto support the anterior metatarsal arch.

Mr. P. BERNARD ROTH (London) emphasised thepart played by the following setiological factors :-(1) tight socks in children ; (2) trauma ; (3) heredity ;and (4) infection. He favoured the operations of

simple trimming of the metatarsal head or completeexcision.

Mr. W. ROWLEY BRiSTOW (London) stated thata survey of the results of the cases operated on inhis clinic had shown that excision of the metatarsalhead gave exceedingly good functional results. Hewas less satisfied with the results obtained after theoperation of simple trimming.

Dr. G. HoLMES (Harrogate), who confined hisremarks to conservative treatment, laid emphasison the value of paraffin baths for the subjectivesymptoms of pain and discomfort.

The Operative Treatment of Arthritis Deformans of theLarge Joints.

ivir. HERBERT jj’RANKLING (Harrogate) read a shortcommunication on the results obtained in a personalseries of operations on the hip- and knee-joints in casesof arthritis deformans. The cases were carefullychosen and the operations were conducted only aftera long period of medical treatment. He statedthat it was important to approach each operationas an exploratory procedure with no fixed routinein mind, the actual technique being determined aftera careful inspection of the interior of the jointhad been made. His results had been carefullvanalysed and it was gratifying to know the degree of comfort and mobility which had developed in anumber of cases after comparatively conservativeoperative measures.

Acute Arthritis of the Hip.Mr. S. T. IRWIN (Belfast) described a series of cases

of acute arthritis of the hip-joint in which mechanicalproblems of considerable difficulty were presentedin the later stages. He pointed out that if in thiscondition and similar acute infections early correct

splinting and postural treatment had been employed,many of the later difficulties would never have arisen.

Lesions of the Ulnar Nerve in the Region ofthe Elbow.

Mr. HARRY PLATT (Manchester) dealt with somepoints in the pathogenesis and treatment of certainforms of ulnar nerve lesion in the region of theelbow, which he divided into three classes: (1)Lesions associated with recent fractures of the lowerend of the humerus. An ulnar nerve lesion accom-panying a fracture of this type was an uncommoncomplication, and usually was a transitory pheno-menon. If the signs of severe neuritis persistedoperation was indicated, and the nerve should be

displaced to the front of the elbow. (2) Late involve-ment of the ulnar nerve. For this condition, inwhich various types of reconstructive operationshad been practised, the operation of anterior trans-position of the nerve was also effective. (3)Recurring dislocation of the nerve. Here againthe operation of anterior transposition should beregarded as a routine procedure.

EXHIBITION OF INSTRUMENTS, DRUGS,FOODS, AND APPLIANCES.

BRIEF mention has already been made of the veryvaried and complete exhibition of surgical instruments,appliances, drugs, foods, and other objects of medicalinterest, which was held in the Windsor Halls,Morley-street, Bradford, from Tuesday, July 22nd,until Friday, July 25th. The educational value ofsuch an assemblage was the ’subject of Mr. BasilHall’s remarks when, as President of the Association,he opened the exhibition, and the attendancethroughout the week showed that his view was

taken by many of those who were attending themeetings.

SURGICAL INSTRUMENTS AND APPLIANCES.

The exhibit of surgical instruments, general andspecial, was as full and instructive as in recent years,with a number of ingenious contrivances of the last12 months added. [49] Allen and Hanburys, Ltd.(Bethnal Green, London, E.C. 2) : an extensivesurgical exhibit, including a model of the new St.Bartholomew’s Hospital pattern operation table, theminimum height of which has been reduced to32 inches, and which includes a new arm-rest forsupport during removal of axillary glands, and anarm-support for use in the kidney position. Amongother recent models were the latest pattern of Boyle’sgas, oxygen, and ether apparatus, insulin syringes asmade for Dr. Leyton, the newest forms of blood-transfusion apparatus, and sets of electricallyilluminated diagnostic instruments.—[6] Arnold andSons (John Bell and Croyden, Ltd., 50, Wigmore-street, London, W. 1) : an improved operation table,at a moderate price, on an oil-punip base, the wholecontrol of which is from the head end of the table,within the surgeon’s easy reach ; also a new self-retaining abdominal retractor, designed by Mr. H. B.Devine, of Melbourne, giving an extensive view of thefield of operation.—[44] Down Bros., Ltd. (21,St. Thomas’s-street, London, S.E. 1) : a large andrepresentative collection of surgical instruments andappliances, including recent introductions and modifica-tions suggested by surgeons, many of the instrumentsbeing made in stainless steel-e.g., Childe’s crushingclamps and forceps ; Fraser and Dott’s guillotine foraseptic intestinal anastomosis ; Ryle and Einhorn’stubes for gastric and duodenal analysis ; instrumentsfor lung surgery by Duval, Tuffier, and de Quervain.- [2’7] The Holborn Surgical Instrument Co., Ltd.(26, Thavies Inn, London, E.C. 1) : an exhibitcovering most branches of modern surgery, of specialinterest being a pocket record syringe to be readilycarried about, sterilised in a water-tight container,and a simple and ingenious form of pantoscope,

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both listed at very moderate price.-[25] Mayer andPhelps (59, New Cavendish-street, London, W. 1) :a selection of instruments and apparatus of originaldesign for general and regional surgery, including avery practical form of blood-pressure outfit witharm-band and dial ; and Daniell’s apparatus foradministration of warmed ether vapour. An extremelyrigid operating table by this firm is on view atthe Wembley Exhibition. Point was made of an

absolutely boilable silk of unbleached fibre.-[54] Reynolds and Branson, Ltd. (Leeds) : a largeexhibit of special instruments, including those usedby Sir Berkeley Moynihan in abdominal surgery,most instruments being in stainless steel, not exceptingthe knives themselves. A set of apparatus andsolutions designed for the use of the general prac-titioner in the diagnosis of glycosuria and diabetes.-[241 C. F. Thackray (Gt. George-street, Leeds, and119, High Holborn, London, W.C. 1) : a collectionof abdominal and surgical instruments, includingRufus Harris’s extension apparatus with a springbalance up to 251b. applicable to any Thomas’ssplint, obviating the use of pulleys and uprights, andnot pinning the patient down to the bed.-[2] JohnWeiss and Son, Ltd. (287, Oxford-street, London,W. 1) : besides a complete display of instruments,including many new and original designs, a verypractical projection lamp for throwing on the screenany microscopic slide and giving a 7-foot disc in adark room with an ordinary wall-plug attached toa lighting circuit. Also a new epidiascope with nofilament.Among the special instruments :-[15] Ajax Electro-

Medical Apparatus (117, Central-street, London,E.C. 1) : with special emphasis on a new sinusoidalgenerator requiring only a little water from the tapto render it capable of furnishing a wide range ofcurrents for treatment.-[20] Ardente Acoustique(Mr. R. H. Dent, 95, Wigmore-street, London, W. 1) :in addition to a series of apparatus for the relief ofdeafness characterised by absence of adventitioussounds and metallic timbre, a stethoscope speciallydesigned for doctors suffering from deafness, and achurch installation rendering it possible for deaf ifpeople to hear the service from any part of the

building.-[3] The Dowsing Radiant Heat Co., Ltd.(91, Baker-street, London, W. 1) : the latest formof apparatus for giving radiant heat treatment bymeans of luminous rays, with a bed of new designand simpler construction.-[36] The Genito-UrinaryCo., Ltd. (64, Great Portland-street, London, W. 1) :a selection of cystoscopes, urethroscopes, broncho-scopes, oesophagoscopes, of various types, includingthe latest improvements and the inventions fordiagnosis and treatment associated with the namesof Thomson-Walker, Swift Joly, Frank Kidd, A. C.Morson, and others.-[32] Theodore Hamblin, Ltd.(15, Wigmo’re-street, London, W. 1) : a number ofophthalmic instruments, including a new luminousMorton ophthalmoscope to be used with both thedirect and indirect methods, and a new prismaticbinocular loupe giving a large flat field with threemagnifications.-[43] Rayner and Keeler, Ltd. (dis-pensing opticians in London, Bradford, Liverpool,Leamington, and other towns. Works: Kemp Town,Brighton): a luminous ophthalmoscope with standardMorton body and improved May type of illumination ;an operating lamp with triple beam mounted onadjustable sling support ; and a new fitting of theMoorfields lamp giving an intense beam for needlingwhich can be used also as a slit lamp.

Besides those firms mentioned as supplying dress-ings :-[47] Antiphlogistine (Denver Chemical Manu-facturing Co., London, E.C. 3) : the well-knownhygroscopic antiseptic poultice for use in inflammatoryand congested conditions both superficial and deep-seated.-[34] Thermogene Curative Wadding (TheThermogene Co., Ltd., Haywards Heath, Sussex) :a scientifically prepared cotton-wool impregnatedwith various medicinal essences, intended to stimulategently the circulation in the affected part.

DRUGS AND PHARMACEUTICAL PREPARATIONS.

The collection of drugs and pharmaceutical pre-parations was, as usual, large and representative,containing for the most part new and improvedforms of well-tried remedies rather than a host ofnew synthetic drugs. [49] Allen and Hanburys, Ltd.(37, Lombard-street, London, E.C. 3) : the phar-maceutical section of this firm’s exhibit includedinsulin A.B. brand, with a special set of apparatusand reagents for the estimation of blood-sugar byMaclean’s method ; the various forms of Allenburysfoods for infants, and diabetic four ; numerous

polyglandin preparations and osmokaolin preparedby electro-osmosis, in colloidal form, for the treat-ment of intestinal toxfcmias.—[55] Boots Pure DrugCo., Ltd. (Station-street, Nottingham) : amongsta large exhibit of fine chemicals, tablets, pastilles,tinctures, were specially to note insulin, acriflavin,stabilarsan, and chloramine T. Details were avail-able of the strict system of analyses made by expertchemists in the firm’s laboratories before the use ofany raw material, of the running control duringmanufacture, and examination after packing.-[46] C. J. Hewlett and Son, Ltd. (35, Charlotte-street,London, E.C. 2) : a number of well-establishedoriginal preparations, including deliciol, a coloured andflavoured soft paraffin ; evapogens, a rnedicatedevaporating skin lotion ; iodermiol, a non-irritatingpreparation of iodine ; and Dr. Crofton’s humantubercle bacillus solution on which demonstrationswere being given.-.[56] The Hoffmann La, Roche

-

Chemical Works, Ltd. (7, Idol-lane, London, E.C. 3) :besides the well-tried sedobrol, in -tablet form forpreparing a hypnotic bouillon, and omnopon in variousforms, a new non-narcotic; non-habit-forming hyp-notic and analgesic was shown bearing the nameallonal, coming with recommendation from theJefferson Medical College, and spasmalghi, a com-bination of omnopon, papaverin and atrinal, forrelieving pain in dysmenorrhoea and colickyconditions.-[38] Oppenheimer, Son and Co., Ltd.(179, Queen Victoria-street, London, E.C. 4) :besides the palatinoids, bipalatinoids, pulverettes,and various roboleine compounds, an oxygen gene-rator and oxinhalator, providing oxygen gas fromchemical cubes in a high state of purity, for use incountry districts and under circumstances wherecylinders of compressed gas are not available.-[50] Parke, Davis and Co. (50, Beak-street, Regent-street, London, W. 1): in addition to a large varietyof pharmaceutical and toilet preparations, bacterialvaccines prepared in the Department for TherapeuticInoculation at St. Mary’s Hospital, anti-diphtheriticserum containing 1400-1500 units per c.cm, Dr.Owen F. Page’s tuberculin insufflation outfit, as wellas hmoplastin, a sterile fluid for venous injection,reducing the coagulation time of the blood.-[54]Reynolds and Branson, Ltd. (Leeds) : among a largeexhibit in this class, concentrated emulsions formaking medicated waters more cheaply than on aspirit basis; unguentum sedativum R. & B., a healingand antiseptic ointment containing calamine andpitch, of proved utility in many skin affections.-[4] Sandoz Chemical Co., Ltd. (Canal-road, Bradford):scillaren, femergin, felamine, and ipecopan in tabletform, as well as a useful dietetic and digestive biscuitknown as matinol, incorporating highly refinedpetroleum to the extent of some 20 per cent., anelegant regulative medium.—14] E. R. Squibb andSons (80, Beekman-street, New York) : thrombo-plastin, a lipoid prepared from the brain of the ox,by Dr. A. F. Hess’s method ; and thyroxin, a

physiologically active ingredient of thyroid, contain-ing 65 per cent. of iodine.—[40] W. A. Wharram, Ltd.(34, Lady-lane, Leeds) ; a series of popular pepsinpreparations, the digestive ferment being combinedin various ways with bismuth, nux vomica, strychnine,iron and aromatics ; various elixirs including a

cardiac tonic, luminal, compound senecio andviburnum.; and a number of original mixtures and

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syrups.-[29] Wyleys, Ltd. (Coventry) : among 7other pharmaceutical specialities. an emulsion of 1

acetyl-salicylic acid, 5 grains to 1 drachm, pleasant -’to take and acting quickly, and a compound theocin smixture, containing 1 grain of theocin-sodium- iacetate to the drachm. <

A number of special pharmaceutical preparations (

were shown. [48] Armour and Co., Ltd. (Queen’sHouse, Kingsway, London, W.C. 2): beef cubes,claimed to have a more intensive beef flavouring 1

than any other cube on the market, and an exhibit iof endocrines comprising tablets, capsules, powder 1

and liquids, including a pituitary liquid prepared -.to a physiological standard.-[23] Crookes’ Collosols i(The Crookes Laboratories, 22, Chenies-street, London,W.C. 1): in additon to argentnrn, bromide, calcium,ferro-malt, iodine, kaolin, and sulphur in a colloidform, also collosol ichthyol in ointment and capsules,obtained solely from British shale.--[35] J. C. Eno,Ltd. (Victoria Embankment, London, E.C. 4) : thewell-known effervescent saline laxative, containingno crude mineral substance and free from sugar.-[51] G-enatosan, Ltd. (Loughborough) : nasmin, a

germ-killing snuff ; sanatogen, the well-known tonicfood ; formamint, to combat mouth and throatailments ; and a collection of detoxicated vaccinesclaimed to be 50 to 100 times less toxic than ordinaryvaccines.-[53] ] Teyes’ Sanitary Compounds Co., Ltd.(64, Cannon-street, London, E.C. 4): preparations ofcyllin, a non-irritant and non-caustic antiseptic [with a Rideal-Walker coefficient for B. typhosusof 22 to 26 ; also a form of lysol (jeysol) for usewhen a clear solution in water is required.-[18]The Anglo-American Oil Co., Ltd. (Albert-street,Camden Town, London, N.W. 1): nujol, an intestinallubricant manufactured to a standard viscosity,approved by clinical and chemical tests; and mistol,an oily solution for use in an atomiser along withcamphor, menthol or eucalyptol.

. Apart from the firms already mentioned, toiletpreparations were shown by: f42] Kolynos, In-corporated (Chenies-street, London, W.C. 1 ) : an

antiseptic dental cream not interfering with thenormal secretions of the mouth and free from grit.-[22] The Pepsodent Company (42, Southwark Bridge-road, London, S.E. 1): a dentifrice containing mildlyacidic calcium salts stimulating the secretion of saliva ;and the decoater tooth-brush designed for use there-- with, in convenient pocket forms for travelling.’ FOOD PREPARATIONS.

Foodstuffs and food accessories were representedby a large number of separate exhibits. [59] CadburyBros., Ltd. (Bournville, Birmingham) : the usualexhibit of Bournville cocoa and chocolates, con-

forming to the highest standards of purity anduniformity.-[13] Food Education Society (329,Vauxhall Bridge-road, London, S.W. 1) : publicationson dietetics and hygiene, including The Gateway ofHealth, Facts for Patriots, Feeding of Children, Dietin Pregnancy, and a new pamphlet on Puddings andPorridge. The Society, which is undogmatic andphilanthropic, sets out to educate the public inmatters of food, cookery, and health.-[26] FoodProducts, Ltd. (11, Queen Victoria-street, London,E.C. 4) : an exhibit of bovo-lactin in various forms,a product rich in assimilable animal protein, iron,and with a high vitamin content. Diluted with sodawater it is recommended as a refreshing and stimu-lating drink for summer sports such as tennis.-167] William Gaymer and Son, Ltd. (Attleborough,Norfolk) : various brands of Gaymer’s cyder,prepared from Norfolk apples, including the original" dry " brands which have received favourablemedical comment.-[57] Glaxo (J. Nathan and Co.,56, Osnaburgh-street, London, N.W. 1) : standardiseddried milk products, including Prescription Glaxo, anew humanised form with a normal fat, low protein,and high carbohydrate content, particularly suitablein the early weeks of infant life and in cases ofdifficult assimilation, malnutrition, constipation, andso forth. When reconstituted with hot boiled water,

1 in 8, a milk is obtained with protein content aslow as that of human milk-namely, 1-7 per cent.A report is available from a London hospital wheresince December, 1923, 15 infants have been fed uponit with satisfactory results. In no case did the milkcause vomiting, diarrhoea, or constipation, and in nocase did the infants fail to gain in weight.-[45]Horlick’s Malted Milk Co. (Slough) : recommendedas an ideal food from infancy to age, and as filling auseful place in Red Cross work-for the ease with whichit is prepared ; also available in the form of foodtablets.-[52] Milkal, Ltd. (31, St. Petersburgh-place,Bayswater, London, W. 2) : a dried milk producedin a modern creamery from milk of Devonshire herds,under the supervision of inspectors, the drying beingcontrolled by qualified chemists. The powder doesnot contain pathogenic organisms, and the numberof other organisms remaining is low. It is claimedthat there is hardly any coagulation of albumin,and that the calcium-casein balance is undisturbed.-[63] Numol, Ltd. (Newcastle-on-Tyne): a dieteticpreparation containing malted carbohydrates,proteins, fat, lecithin, glycerophosphates, hypc-phosphites, diastase, and lemon; originally knownin northern hospitals as " extractum nutriens," andcontaining 12’5 per cent. of animal fat. Also a non-irritant, non-poisonous antiseptic known as soloform,with the formula C6H2IaOH, which can be usedundiluted and is available in special form for immediatesterilisation of surgical instruments.-[30] Oxo, Ltd.(Thames House, Queen-street-place, E.C. 4): Oxofluid beef, being a concentrated form of stimulatingextractives together with easily digestible con-

stituents of fresh, lean beef, seasoned ready for use,as well as Lemco, a pure unseasoned beef extractand beef essence for invalids and convalescents;also Oxoid brands of gland extracts, includingthyroid, pituitary, and adrenal, in tablet form.-[33] Prideaux’s Pure Casein Co., Ltd. (16, Southwark-street, London, E.C. 1) : the Dorsella milk food,described as modified full-cream milk dried withina few hours of milking, with the addition only oflactose ; half-cream milk powder for special prescrip-tion is also supplied. Casumen contains nearly 90 percent. of casein and is completely free from starch andsugar.-[28] Virol, Ltd. (Hanger-lane, Ealing, London,W. 5): containing fats, carbohydrates, and proteinsin well-balanced proportions and abundance ofvitamins not destroyed in the process of manufacture;also virolax and the new virol and milk in goldenpowder, combining the properties of virol with full-cream Devonshire milk, and recommended for nervousand mental fatigue and for athletes in training.

MEDICINAL AND MINERAL WATERS.

[60] Bath (Mr. John Hatton, Director of Baths):an exhibit of photographs of the bathing establish-ments and water-colours of features of interest in andaround Bath, with a special reference to the comingannual meeting of the Association at Bath in 1925.-[31] Droitwich (Mr. J. H. Hollyer, Joint GeneralManager of Bathing Establishments) : a spa depen-dent for its therapeutic claims upon natural wateronly, the heavy brine constituting the strongestsaline water known and facilitating the movementsof immersed limbs ; highly radio-active and radio-emanative.-[39] Harrogate (Mr. F. J. C. Broome,General Manager) : unique in the diversity of itssprings, with 87 waters each possessing distinctivecharacteristics, and under the supervision of a

permanent scientific officer and analyst. The bathingequipment was visited by many members during theannual meeting of the Association.- Ingram andRoyle, Ltd. (45, Belvedere-road, London, S.E. 1) :samples of imported natural mineral water, salts, andpastilles, including Vichy-Celestins, Contrex&eacute;ville-Pavillon, Evian-Cachat, Hunyadi-Janos, Carlsbadsprudel salt, and 22 others.

MICROSCOPES AND SCIENTIFIC APPARATUS.[19] Baird and Tatlock, London, Ltd. (14, Cross-

street, Hatton Garden, London, E.C. 1) : an impres-

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sive exhibit of autoclaves, incubators, centrifuges,stenlisers, glass apparatus, stains, and media, includingapparatus for determination of sugar in blood,Harris’s air analysis, and an all-British Benedictmetabolism apparatus.-[9] C. Baker (244, HighHolborn, London, W.C. 1) : a collection of micro-scopes and accessories to meet the needs of thestudent, advanced student, and research worker;also a new corneal magnifier and illuminator, withpossible application to other clinical purposes.-[10] F. Davidson and Co. (29, Great Portland-street,London, W.1): a variety of optical and electro-medical appliances and portable outfits for examina-tion of the ear, nose, and throat, trans-illuminationand cautery; also a new pharyngoscope on theprinciple of the cystoscope.-[7] Chas. Hearsonand Co., Ltd. (47, Mortimer-street, London, W. 1) :sole agents in Great Britain for Reichert microscopesand accessories ; in addition to bacteriologicalapparatus, such physiological apparatus as kymo-graphs, recording drums, respirator pumps, time-marking clocks, myographs, hsemocytometers, andso forth. This firm submits designs and carries outmanufacture of apparatus for new experimentalwork.-[5] Kodak, Ltd. (Kingsway, London, W.C. 2) :showing duplitised X ray films, positive prints onnikko-bromide paper, and reduced transparencies onEastman commercial film ; a series of very beautifulradiograms.-[62] Ronuk, Ltd. (Portslade, Sussex) :materials and appliances employed in the preparation,initial polishing, and maintenance of floor and otherinterior woodwork by improved sanitary methods.-[65] Short and Mason, Ltd. (Aneroid Works,Walthamstow, London, E. 17) : the Tycos sphygmo-manometers, calibrated to standard readings and self-verifying.

MEDICAL AGENCIES. -

[1] The Medical Charities : Royal Medical Benevo-lent Fund and Epsom College.-[37] The MedicalInsurance Agency (429, Strand, London, W.C. 2) :founded in 1907 to persuade medical men to protectthemselves by means of insurance against adversefortune and unsatisfactory contracts, and to assistthe medical charities.- The Medical Sickness,Annuity, and Life Assurance Society, Ltd. (300, HighHolborn, London, W.C. 1) : founded in 1884 as amutual society of medical and dental practitioners,with the object of obtaining sickness, accident, andlife assurance on better terms than are offered byproprietary companies.

BOOKS AND OFFICE ACCESSORIES.

[31] H. K. Lewis and Co., Ltd. (136, Gower-street,London, W.C. 1) : an exhibit of new and importantbooks in many branches of medicine, including thoseof the Cambridge University Press ; additions to thestock of medical stationery-e.g., new cards for X raytreatment and electrical treatment in the card indexsystem. The printed library catalogue has beenkept up to date by two supplements, 1918-20 and1921-23.-[16] The Oxford University Press (Warwick-square, London, E.C. 4) : a set of the Oxford MedicalPublications, comprising text-books and works onmedical, surgical, and allied subjects, and severalrecent and important additions.-[12] Stanley Phillips(45, Brondesbury-road, London, N.W. 6) : a collectionof the latest publications of Messrs. F. A. Davis Co.,Philadelphia, E. and S. Livingstone, Edinburgh,and Cassells, London ; including the PracticalMedicine Series of Year-books on general medicine,surgery, and special subjects.-[64] W. B. SaundersCompany, Ltd. (9, Henrietta-street, London, W.C. 2) :a number of new books and new editions, includingPaediatrics by 150 authorities ; Operative Surgery,edited by W. S. Bickham, in four volumes, andother standard books.-[17] Tapp and Toothill,Ltd. (Bradford) : a set of office indispensables, includ-ing the ingenious Bates rotary telephone index.-[41] John Wright and Sons, Ltd. (Bristol) : a, series ofnew publications, including Epidemic Encephalitis, iby Prof. A; J. Hall; Diseases of the Nose, Throat I

and Ear, edited by Dr. A. Logan Turner ; and neweditions of standard medical works.

Corrigendum.-In our report of the Section of

Ophthalmology (THE LANCET, August 9th, p. 295,col. 1, five lines from the bottom) the sentence shouldread : " The beam should be directed at a suitableangle so as to avoid the specular reflection from thecorneal epithelium."

Correspondence.

THE VIRUS OF FOOT-AND-MOUTH DISEASE."Audi alteram partem."

I To the Editor of THE LANCET.MIR,&mdash;The photographs of the colonies and of the

individual organisms of the virus of foot-and-mouthdisease reproduced in THE LANCET of August 2nd willno doubt be of interest to many workers in bacteriologyand allied sciences. In common with most Englishreferences to this recent discovery, the descriptionyou give is not quite accurate. The photo-micrographshave been obtained by using ultra-violet light as anilluminant, but the apparatus used is not the ultra-microscope as might be inferred from your article.An ordinary type of microscope was used, but it isfitted with objectives and condensers of quartz. Thelight source is provided by passing a high tensionelectric discharge between cadmium electrodes, thedesired wave-length in the ultra-violet (275 ILIL) beingisolated spectroscopically.No doubt the similarity of the terms " ultra-violet

microscopy " and " ultra-microscopy " has led to someconfusion, but the purpose of the two methods iswidely different. The terms themselves are perhapsopen to objection, but as they are in general useand are recognised by microscopists as applying todifferent branches of work, it is difficult to alter them.Any confusion in their use is probably due to failureto appreciate that there are two distinct microscopicalmethods. In one the aim is to obtain the utmostresolution, in the other to obtain the greatestvisibility. Resolution is dependent on the wave-lengthof the light used and on the numerical aperture of theobjective, whereas visibility is mainly dependent onthe intensity of the illuminant. Resolution is thedesideratum in all ordinary observational work withthe microscope and the use of ultra-violet light comeswithin this category, although the image itself isinvisible and has to be recorded photographically.The difference between the use of white light inwhich the dominant wave-length is of the order of(say) 550 ILIL and ultra-violet light of wave-length275 ILIL, is that resolution is doubled, such increase ofresolution proceeding regularly as the wave-lengthused is reduced. Thus objects of half the size of thoseseen by white light may be satisfactorily shown.The organism of foot-and-mouth disease is pre-

sumably of the order of size that can be photographedin ultra-violet light (about 0.1 IL), while it would beimpossible to resolve it by any method in whichwhite light is used. The method has other and perhapseven greater advantages for biological work, as

organisms do not require any preparation beforebeing photographed ; they can be dealt with in theliving state. Now the ultra-microscope secures

increased visibility, and there is no theoretical limitto the size of an isolated object that can be madevisible by this means; it is in general merely a questionof whether the object can be made sufficientlyluminous to be seen. The light used is therefore ofhigh intensity, usually an arc-light or sunlight, andillumination is at right-angles to the direction ofobservation. The image obtained of a small particleis a circular disc of light giving no indication of itsshape or size. It follows, therefore, that this methodis of limited application, and it is in practice confinedto the observation of colloidal particles. The ordinary