a clinic for functional nerve cases

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within eight days from the date of the appearanceof the initial case of the outbreak. In addition therewere 11 secondary cases. Inquiry showed that ofthese 33 primary cases 28 had definitely eaten sus-pected food, certain " head-cheese," a form of brawn,and the other five had eaten beef bought and servedat the time when the suspected brawn was purchased.Circumstantial information from certain individualcases shows clearly that the source of infection was thesubstance called in the report " head-cheese." Nosamples were available for bacteriological examination.but the food was prepared and sold by the proprietorof the meat market and his wife. It was ascertainedthat the wife had been ill, for a period of approxi-mately four days, about three weeks before the out-break. She assisted in preparing the suspected foodtwo days before it was placed on sale. It was notfound possible to examine her blood serologically,so the presumptive evidence that she was the causeof the outbreak could not be tested.The little outbreak is of interest from two points

of view. One is that recorded outbreaks of para-typhoid fever from contaminated food are still com-paratively rare. The chief point of interest is thelight it throws upon food-poisoning outbreaks. Theprevailing German view, one also largely followed inAmerica, is that the food-poisoning bacilli of theB. aertrycke or B. suipestifer types are identical withB. paratyphosus B-i.e., in other words, that thesame bacillus may at one time cause paratyphoidfever, at another an attack of food poisoning. In thepresent outbreak, although an article of food wasinfected, apparently of similar nature to the foodswhich do convey food-poisoning bacilli, the resultingoutbreak was paratyphoid fever, and did not showthe clinical features of food poisoning. There wassome, but not conclusive, evidence that infectionoriginated from an unrecognised human case ofparatyphoid fever and the infection bred true. Thecases were all of one type, supporting the conceptionthat B. paratyphosus B is a different strain not onlyserologically but in its aetiological functions fromB. aertrycke and other bacteria associated with food

Ipoisoning, the one type causing paratyphoid feveronly, the latter food-poisoning infections only. ’

POROKERATOSIS.

ACCORDING to Dr. Carroll S. ’right,1 instructor indermatology and syphilology at the University ofMichigan Medical School, who reports an illustrativecase in a man aged 40, porokeratosis was first describedsimultaneously by Mibelli and Resphighi in 1893.Since then not more than 60 cases have been recorded,the condition being particularly rare in the UnitedStates. In spite of the numerous theories thathave been advanced the aetiology of the conditionis still entirely unknown. Heredity undoubtedlyplays a part, as was shown by two of Mibelli’s cases,in which a brother and sister were affected, and hassince been illustrated by many other cases, includingDr. Wright’s, in which the grandfather, father, anda daughter of the patient were affected. Thedermatosis may begin at any age, but, as a rule, itfirst appears in the earlier years of life. Dr. Wright’spatient had had his lesions since infancy, the father’slesions had been present throughout life, and thedaughter, who was 9 years of age, had had a typicallesion on her leg since infancy. Clinically porokeratosisis characterised by the occurrence of elevated wart-like lesions which, as they enlarge, form an irregularperipheral wall surrounding an atrophic depressedcentre. The lesions show a distinct predilection forthe hands and feet, genitals, buttocks, and scalp,although they may appear on any site. In a highpercentage the mucous membranes are involved.The palms and soles almost invariably escape.Histologically the condition consists first in acanthosisand inflammatory changes in the corium, which arerapidly followed by hyperkeratosis with plugging

1 Archives of Dermatology and Syphilology, October, 1921.

of the sweat ducts and follicles. except in the casesof individual lesions, which can be removed byexcision or carbon dioxide, treatment is ineffectual.According to Dr. Wright, porokeratosis is to beclassified under the group of verrucose neevi, becauseof the wart-like condition of the lesions clinically,the epidermal hypertrophy as observed histologically,the familial tendency, the non-contagiousness, thepersistence throughout life, the absence of inflam-matory changes, the occasional systematic arrange-ment, and the failure to undergo involution as theresult of X ray treatment.

YAWNING: ITS PHYSIOLOGY ANDPSYCHOLOGY.

YAWNING is one of those curiously modified

respiratory acts which has important physiologicalMid psychological relations, not the least remarkableof the latter being what might almost be called its" infectious " nature, associated with imitation on thepart of the beholder, and which in some people maybe excited by thinking intensely of the act itself.C. Mayer in Zeitschrift f. Biologie (vol. Iv., 1921)gives the results of his investigations in man byinspection, laryngoseopy, and X rays. The act itselfhe divides into three phases : 1. The initial phase,beginning with inspiration, widening of the chest,descent of the diaphragm and larynx until a certaindepth of descent of both is reached, elevation of thewings of the nostrils, of the soft palate, drawing ofthe tongue upwards and backwards, dilatation of therima glottidis. 2. The acme stage, full dilatation ofthe thorax to its greatest extent by means of theintercostal and accessory muscles, and descent of thediaphragm and larynx to their lowest position,accompanied by maximum depression of the lower jaw,further retraction of the tongue, and elevation of thesoft palate. Tonic contraction of a varying numberof individual muscles of the neck, shoulder, and regionof the trunk. Wide lateral expansion of the mouth,closing of the eyelids, noise in the ears due to con-traction of the tensor tympani, and a subjectivefeeling of pleasure and satisfaction. 3. Final phase,a short expiration, relaxation of the contractedmuscles, ascent of the diaphragm and larynx, andelevation of the lower jaw, secretion of tears, anddeglutition. The duration of the tonic contractionof the individual muscles is about 2-46 seconds,that of the whole inspiratory phase (phases 1 and 2)about 5-5 seconds. The biological significance of theacts seems to lie in the energetic ventilation of thelungs. The tonic phenomena accompanying the actcan only in part be explained by the irradiation of theinspiratory impulses. This circumstance, along withthe accompanying stretching of the arms and exten-sion of the trunk, seem to indicate that the act ofyawning and the participation therein of the pro-nounced contraction of certain muscles is of import-ance for aiding both the circulation and metabolism.The act itself would seem to be sub-cortical in origin,though it may be excited or discharged by psychicalimpulses. Spontaneous yawning is an expression ofcerebral fatigue and the processes leading up to itstands in intimate relation to the function of sleep.If the optic thalamus is the part of the brain intimatelyconcerned with sleep, then at a certain stage offatigue the motor impulses for the act of yawningmay proceed from it. In certain cases of encepha-litis lethargica the execution of the act of yawningmay be disturbed and modified.

A CLINIC FOR FUNCTIONAL NERVE CASES.

IT is generally recognisecl Lnat. progress in anaiyticaipsychology and experience gained during the warhave together brought about notable advances inour methods of treatment. The Tavistock Clinic forFunctional Nerve Cases was opened in September,1920, in order to bring modern treatment for suchconditions within reach of those who cannot affordspecialists’ fees, and to act as a centre for the study

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and practice of psychotherapy. The methodsemployed include persuasion, suggestion, re-education,and various forms of analysis ; no attempt is made tosecure uniformity of method, since members of thestaff may belong to different schools of thought, and,moreover, no rules can be made in the treatment ofnerve cases. The aim in all cases is to restore the patientto social efficiency as quickly and as permanentlyas possible. Patients bringing a letter from their owndoctor require no other recommendation, and payif they can afford to do so. 219 patients have beentreated during the year, involving 1784 interviews,lasting an average time of 50 minutes. Most of thecases treated in the children’s department havebeen delinquents, chiefly thieving, and the results aresaid to have been uniformly good. Treatment hasalso been given for nocturnal enuresis and otherdisorders. Lectures and demonstrations are held forpractitioners and medical students. A course on

elementary psychotherapy is now being given byDr. H. Crichton Miller, and during the coming yearcourses will be given by Dr. C. P. Symonds, Dr. J. A.Hadfield, Dr. E. W. N. Hobhouse, and Dr. W. A.Potts, who is the director of the children’s depart-ment. Particulars of these courses may be obtainedfrom the Hon. Lecture Secretary at the Clinic,.51, Tavistock-square, London, W.C. 1. While patients’fees and lecture fees go some way towards meetingthe current expenses of the clinic, they are notsufficient to make it self-supporting, and help isurgently needed to enable the work to be carried onand extended.

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CHEMICAL DISINFECTION AND STERILISATION.

Ix a recent publication 1 Dr. S. Rideal and his sonconsider not only the various chemicals used as

disinfectants and sterilisers, but also the details oftheir practical use, with some account of the experi-ments performed in connexion with their testing.A clear summary of the theory and technique ofdisinfection and sterilisation by chemical means willbe welcomed by members of the medical profession aswell as by numerous scientific workers.Chemicals such as sulphur, copper, nitre, and

numerous aromatic substances have been used fromearly times, but the number of suitable substances isnow so large that a choice between them must some-times be difficult. Moreover, the quantities of thesteriliser to be employed, their times of action, as

well as the best forms of apparatus for their productionare of the utmost importance. Selection must dependlargely on the nature of the object to be treated.Air may be sterilised by formaldehyde, sulphurdioxide, chlorine, and ozone. Chlorine is seldom used ;formaldehyde and sulphur dioxide are mainly usedfor rooms, whilst ozone is suitable for large spaces.Chemicals used for food preservation must be chosenso as not to be injurious to health on consumption.There is thus only a limited choice, which is confinedto those required for salting and smoking. Food ingeneral is most commonly preserved by cold storage,milk by condensation and heat sterilisation. Watersterilisation is effected by filtration and sedimentation ;ozone is sometimes used, but most frequently lime.Halogens as such or in the form of hypochlorites arealso largely used. The destruction of non-bacterialparasites, such as insects, is another special problem ;it is only successful when we know the life-historyof the insect and is generally prophylactic in nature.The mode of action of the chemicals necessarilyvaries, being dependent not only on their own naturebut on that of the object to be disinfected ; physicalprocesses such as ionisation, osmosis, surface tensionplay a large r6le. No specific action can be ascribedto chemical groupings in the molecule.

1 Chemical Disinfection and Sterilisation. By SamuelRideal, D.Sc. Lond., F.I.C., Fellow of University College,London; Public Analyst for the Metropolitan Borough ofChelsea; and Eric K. Rideal, D.Sc. Lond., M.A. Cantab.,F.I.C., Fellow of Trinity Hall, Cambridge ; Owen Jones Lecturerin Physical Chemistry in the University of Cambridge. London :Edward Arnold and Co. 1921. Pp. 313. 21s.

THE REACTION OF THE BLOOD :THE MECHANISM OF ITS REGULATION.

BY C. A. LOVATT EVANS, D.SC.LOND., M.R.C.S.ENG.

THE questions of the reaction of the blood and themechanism of its regulation have attracted theattention of laboratory investigators for several yearspast. Numerous definite results, some of which mayprove to have a practical application to clinicalproblems, have accrued from this originally purelyacademic line of investigation. Their application is,however, largely a matter for future clinical investiga-tion to reveal. It has long been known that blood,like most other tissues, normally has a slightlyalkaline reaction, which it owes to the presence in itof sodium bicarbonate. Despite the fact that thecirculating blood is the receptacle of very variableamounts both of acids and bases-waste productsthrown into it by the active tissues of the body-itsreaction is subject to surprisingly little variation inhealth or even in many pathological conditions.The liver and kidneys contribute a great deal to theregulation of the reaction of the blood, and the lungs,by removing carbon dioxide, constitute a valuablefine adjustment mechanism, but a still finer meansof regulation than any of these resides in the blooditself. Blood is much more than a mere carrier ofoxygen, food materials, and waste products ; it is avaluable means of governing the reaction of all theother tissues in the body, the relation being mutual.

The Modern 1’tleaning of " Reaction."Let us first consider the modern meaning of reaction

without looking too deeply into the physical chemistryof the matter. The theory of electrolytic dissociationteaches that water is to a very small extent decom-posed into two ions, the hydrogen-ion (H) and thehydroxyl-ion (OH), the former bearing a positive andthe latter an equal negative electric charge. Further,acids when dissolved in water add hydrogen-ionsthereto, whereas bases by producing hydroxyl-ionslower the hydrogen-ion content. By the reaction ofa fluid is meant the concentration of hydrogen-ionsin it, and this can be expressed in terms of grammes ofhydrogen present in the ionic state per litre of thefluid. Water itself, the standard of neutrality,contains 1 g. equivalent (i.e., 1 g.) of hydrogen-ionin 10 million litres ; it is exactly neutral because italso contains in the same volume 1 g. equivalent ofhydroxyl-ion. Water, then, may be regarded as

either a 10-millionth normal acid or a 10-millionthnormal alkali. All acid solutions contain more andall alkaline solutions contain less than 1 g. of hydrogen-ion in 10 million litres. The concentration of hydroxyl-ion is usually disregarded, because it always varies inthe opposite way to the hydrogen-ion in such a mannerthat the product of the two concentrations is constantfor all aqueous solutions whatsoever, neither ion everquite vanishing. A simpler way of expressinghydrogen-ion concentration is to say that pure waterhas a H-ion concentration of 1/10,000,000 g., or moresimply 10-’ g. per litre. Similarly a 1/1000 normalacid has a H-ion concentration of 1/1000 g. or

10-3 g. per litre ; while a 1/1000 normal alkali has ahydrogen-ion concentration of 1/100,000,000,000 or

1C-" g. per litre. Since the expression 10-’ means 1divided by 10’ or 10,000,000 and 10-3 means 1 dividedby 103 or 1000, this way of expressing fractions is veryconvenient ; still more convenient for the expression ofhydrogen-ion concentrations is the convention of

omitting the 10 and the minus sign and prefixing theletters pH, writing pH 7-0, pH 3-0, and so on. Thesymbol " p " means " that power to which 10 must beraised to give the concentration in grammes ofhydrogen-ion per litre " of the fluid in question. Sinceit is always negative for solutions weaker than N/1acid, the negative sign is omitted by a convention. By afurther convention, H in pH stands for the hydrogen-ion, and not the element, though usually the ion isdesignated by H+, or more simply H., This so-called