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muscles at 0°C, the events are still too fast to be followedby chemical methods ; there are in fact no chemicaldata whatever on what happens during a single twitch.Physical methods, of which the majority have beendevised by Hill himself, can follow easily and accuratelythe heat-production during and after the twitch, thetension development, and electrical and optical changes.Though very hard to interpret, these physical data areclear and reliable. More than anything else they providea framework into which chemical theories must fit.Some theories can thus be discarded, but more than onecan be mote or less squared with the physicist’s findings.The fundamental event in contraction is the shortening

of a particular protein molecule in the myofibril. Prof.H. H. Weber, of Tubingen, observed at the meeting thatmuscle contains several proteins, of which apparentlyonly two-actin and myosin-are concerned in theactual contractile process. A possible model of the processwas given in a communication by Prof. W. T. AstburyF.R.S. Imagine two strips of paper stretching parallelto each other from north to south, and turned edge-on tothe observer. Fold each of them like a concertina,so that each is crinkled, running first south-east thensouth-west, then south-east, and so on. These representthe myosin molecules in the relaxed state. Between thesetwo scatter some tennis -balls-the globular form ofactin. When the muscle contracts, said Astbury, theactin tennis-balls arrange themselves in chains, one

sticking to another in a straight north-south line ; thisis now the fibrous form of actin. At the same time the

myosin molecule shortens with a concertina action ;the crinkles instead of running south-east and south-west run more nearly east and west, and the edges ofthe crinkles now touch the actin chain. Astbury wasled to this picture by X-ray studies, but not all workersin this field agree that it is true. What is needed, heholds, is an X-ray study of muscle actually while ittwitches; but here, as in chemical studies, technicaldifficulties supervene.What is it, then, that causes the change in form of

the actin and myosin molecules and their association ’This is the central question, to which there is still noanswer. When a nerve impulse reaches the neuro-

muscular junction a wave of activity spreads down thesurface membrane of the fibre, very much as an impulsetravels down a nerve. Somehow this surface diminutionof electric charge sets off the contractile mechanism inthe interior of the fibre ; and probably the movementof ions is one of the links in the chain. But is this literallya trigger action Is the muscle like a stretched springwaiting for a chance to contract-that is, to lower itspotential energy Is contraction or relaxation the moreprobable state, in the technical sense of the phrase ’*This is another question on which there is no agreement.Professor Hill holds strongly to the view that contractionis active and relaxation passive, and the relaxed statethe lower in potential energy. From physical measure-ments he cited considerable evidence to support thisview ; but the evidence is not decisive, and many ofthe chemists had theoretical reasons for holding theopposite opinion. Since it is believed that the energysource of a twitch is the breakdown of adenosine tri-

phosphate the crucial experiment would be to determinewhether this substance breaks down during the contrac-tion phase of the twitch or only when the twitch is over.This is asking too much of the chemists ; Mrs. Dorothy-Needham, F.R.s., indicated that new spectrophometricmethods might be able to detect chemical changesafter a single twitch, but she held out no hope ofestablishing the time relations of the chemical events.

Bit by bit an intricate cat’s-cradle of fact is beingwoven, but the shape of the cat still eludes us ; andone can scarcely see the string for the holes. Not thatthere is anything mysterious or unique about muscular

activity ; as Professor Astbury emphasised, the con-

tractile muscular protein molecules are only a specialadaptation in a general group which includes keratin,fibrinogen, and the epidermal protein of mammals.In human hair there persists the skeleton of muscle-fibres-the machine without the fire to drive-so the per-manent wave has some relation to the athlete’s strength.

EFFECTS OF HEAT AND HUMIDITY IN DEEP MINES

AT the first post-war Empire Mining and MetallurgicalCongress, the technical sessions of which were held atOxford from July 12 to 16, interest in man’s reactionsto underground environments was intensified becauseof the various factors now increasing the difficultiesof the mining industry. Not only is it becoming more ..difficult in different parts of the world to attract labourinto the mines, but it is apparent that in South Africa,India, and even Britain heat and humidity in the deepermines diminish working efficiency to an unknown extent.By contrast with the outstanding success of personnelresearch during the war on similar subjects, the miningindustries have lagged behind in organising heat physio-logy units, not only in this country but also in SouthAfrica.The problems discussed must have left little doubt

of the urgent need for further physiological information.A survey of the environmental conditions in Britishcoalmines by Mr. A. E. Crook, Mr. F. Edmond, Mr. J.Ivon Graham, and Mr. B. R. Lawton revealed that inBritain a wet-bulb temperature of 85°F had been reachedat 3000 feet below the surface. It was agreed ontheoretical grounds by Sir David Brunt, F.R.S., andfrom Dr. A. Caplan’s experience in India, that efficiencyfor strenuous work falls off at wet-bulb temperatures of83-85°F. Caplan and J. K. Lindsay assessed thefall in muscular efficiency as 20% at a wet-bulb tempera-ture of 87°F, and at similar temperatures Mackworthhas demonstrated a reduction in psychological perform-ance. It might be inferred from the agreement betweenCaplan and Brunt that Indian mineworkers work at alevel of energy output defined as strenuous-i.e., about300 Kcal./m2/hr. This would be surprising in the lightof Dr. J. S. Weiner’s observations on the working abilityof Bantu mine-labourers in hot humid conditions.Weiner demonstrated that " raw " and " experienced "Bantu are less well adapted to hot humid environmentsthan young healthy Europeans, acclimatised in experi-mental chambers. It is suggested that Bantu labourersnormally work at a lower energy output than that of theacclimatisation routine (110 Kcal.jm2/hr.). There isno information on the energy output at the various tasksin mining. This extraordinary gap in our knowledgedelays the use by ventilation engineers and physiologistsof Brunt’s integration into a vastly improved thermalbalance equation of the factors concerned in heat-

production and its transmission to and dissipation fromthe body surface to the environment. Thermal balancemay be expressed simply as :

Heat-production . heat-loss by evaporationz- heat-storage

-

z- convection z- radiation.But energy exchanges by convection and radiationcannot be measured directly. C. E. A. Winslow, in 1941,determined these factors experimentally, in terms ofmean temperature of the skin and the walls and the dry-bulb thermometer reading. Brunt has integratedWinslow’s with his earlier work and expressed convection,evaporation, and radiation in terms of readily measurablequantities, thus :

Heat-production = 3,6 (T - Tr) 66-7 Vv (1. - I )- heat-storage -- ’ s Tr) ’ v B a - w

where Ts is mean skin temperature ; Tr is mean temperatureof walls ; Ig and Iw are the total heat content of unit massof dry air, plus the water required to saturate it, at skin

temperature of the wet-bulb thermometer of the ambient air.

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On the basis of the body temperature reaching a steadystate-i.e., when heat-storage = O-Brunt produceda nomogram for the limiting environmental conditionsin terms of wet-bulb temperature and temperature of thewalls for three different rates of energy production.Experimental verification of these limiting conditions isfound in S. Robinson’s work in the United States. Thereis an obvious advantage, either from a physiologicalor an engineering point of view, in being able to measurein heat units the heat-load of the environment on thehuman body. Previous scales of warmth have assessed

equivalent effects and relative severity of variouscombinations of heat, humidity, and air movement interms of single physiological effects such as the subjectivesensation of warmth (effective temperature scale) or

of the sweat-output in 4 hours at a standard work-rate(predicted 4-hourly sweat-rate). Dr. A. 0. Dreosti’s

pioneer work in 1932 on acclimatisation and on the" heat-tolerance test," has been amply verified in thereduction in deaths from heat-stroke. Investigation ofrecent heat deaths in South African mines shows thateach was due to some departure from Dreosti’s rules.

HOSPITAL ADMINISTRATION IN NEW ZEALAND

THE hospitals of New Zealand are governed by forty-two boards elected directly by the people in much thesame way that local councils are elected in Britain.These boards were first set up in 1910, since when thedevelopment of road and air transport and the changesin population distribution and the size of homes andfamilies, to say nothing of medical progress, have quiteoutmoded the original conception of separate bodies

serving fairly small isolated populations.The need for early reorganisation is argued by Mr.

Selwyn Morris and Mr. Douglas Robb 1-two surgeonswho have already contributed much to our under-

standing of the health service in their country. In theirwords,

.

the things that are wrong now are mainly due to faultyorganisation. They include the too large number of toosmall and unrelated administrative units. The constitutionof the Hospital Boards in being wholly selected by popularvote, the unchecked overlap between general medical serviceand hospital work (both paid for by the Social Security Fund),the little use of the recovery or convalescent hospital and thepolyclinic for specialist investigation, the little attention

given to the care of the aged, and the division of authoritybetween the local Hospital Board, on the one hand, and theGovernment Departmental Office, and the Ministerial Officein Wellington."

"

The solution they propose is the division of the countryinto six hospital regions each caring for some 300,000people. These regions they believe would be largeenough for autonomous development on a functionalbasis ; each would provide all services except the super-specialties like brain or heart surgery. " In this way allthe more specialised services are brought to the region,and so nearer home, and the regional board is obliged toprovide itself with a full range of buildings, equipment,and professional skill. To make the regional unitsmaller would make it incomplete and so partiallydependent on remoter control and help." All the

proposed administrative bodies, from the new local

hospital boards through the regional boards to a centralnational hospitals’ corporation, are designed to giverepresentation not only to the people (indirectly throughtheir local councils) but also to the doctors and nursesworking in the service. The principal medical and

nursing officers should, it is suggested, be included asfull members of the board or corporation which theyserve ; while at regional and national levels there shouldbe university representation. The national hospitals’corporation would include a representative of each

1. Hospital Reform in New Zealand. By Selwyn Morris andDouglas Robb. Auckland: Whitcombe & Tombs. Pp. 68.

region together with university and ministerial nominees,and it would deal with questions of national policy oversuch matters as clinical records, vital statistics, anddiseases such as tuberculosis requiring some measure ofnational planning. It would also watch over the distri-bution of finance both for current expenditure and forcapital works. A small peripatetic commission appointedby this- corporation should advise (after the fashion of theUniversity Grants Committee) on the allocation of funds.The British reader of this pamphlet will find much to

stimulate his interest, many problems common to ourtwo countries, and many analogies in the solutions

suggested to the methods we have been trying to initiateduring this last year. Some problems only beginning toappear here--such as the extent to which a hospitaloutpatient department can properly be required toundertake duties within the scope and the terms ofservice of the general practitioner-have obviously beenapparent in New Zealand much longer, though eventhere no solution seems to be in sight. Perhaps thisparticular problem will not be solved in either countrywithout the development of health centres, and a

division of function between these and the hospitals.CONSULTANTS’ AND SPECIALISTS’ CONTRACTS

As reported in our issue of July 9, the Joint Committee,formed by the Royal Colleges and the British MedicalAssociation, decided on July 5 to reopen discussions withthe Ministry on three points-conciliation machinery andarbitration, facilities for private treatment in hospitals,and the remuneration of part-time clinical teachers. Afterreceiving the Ministry’s letter which we printed lastweek, the Joint Committee met representatives of tlieMinistry on July 18, when the following assurances werereceived :

Arbitration.-The Ministry has agreed :(a) That no changes will be made in the terms and

conditions of service without discussion in the

appropriate part of the Whitley machinery, whenestablished, and this will be established as soon aspossible.

(b) That remuneration is a subject which is suitable forarbitration.

(c) That save in exceptional circumstances, and afterthe conciliation machinery of Whitley has beenexhausted, issues of remuneration remaining in dis-pute will go either to arbitration or for inquiry andreport by a committee.

(d) That the words " by the Minister of Health " willbe deleted from the opening paragraph of the modelcontract, so that it would simply refer to the termsand conditions of service " determined from time totime."

Private Practice.-The Ministry reiterated its previousassurances that it was not its intention to place difficultiesin the way of private practice. It has agreed that patientsadmitted to private hospital beds under section 5 of the Actwill pay fees for professional attendance to part-time practi-tioners in addition to the maintenance charges, except wherethe patient is occupying accommodation under the provisoto section 5 (1)—i.e., on medical grounds.The Ministry has also agreed that individual practitioners

are free to leave untouched or to delete from the whole-timecontract any of the clauses which are enclosed in squarebrackets, including clause 5 requiring attendance on patientsoccupying beds under section 5 of the Act who have not madeprivate arrangements under section 5 (2).

Clinical Teachers.-Assurances, shortly to be made public,have been received on the arrangements for the remunerationof clinical teachers.

The Joint Committee decided, with the assent of theMinistry, to continue negotiations on a number of out-standing points. It feels that it is now able to advisehospital staffs to enter into permanent contracts.

Sir DOUGLAS COOKE, F.R.C.S., Conservative M.P. forSouth Hammersmith from 1931 to 1945, died in Londonon July 13 at the age of 70.


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