38

has led him to believe that the humidity of the iatmosphere is the chief factor in determining the I

development of the parasite within the mosquito,and the most striking feature exhibited by themeteorological chart of Murree is the dryness of theatmosphere throughout the greater part of the year.The relative humidity is greatest during the coldestmonths, and in May it is only 41 per cent. Shouldthe mean relative temperature at which this develop-ment can take place be estimated at 63 per cent., itfollows that the potential infection period is reducedin this instance to one of eight weeks. To test thispoint still further, experiments on the transmissionof malaria were undertaken with the local anopheles,

Iespecially A. willmori, and it was found that develop-ment takes place when the temperature remainedconstant-at about 68° F.-with a relative humiditybetween 79 and 94 per cent.-that is, under theatmospheric conditions which prevailed in Murreeduring the months of July and August. The absenceof malaria in these hill-stations must therefore be

ascribed to the very short period during which the Iinfection may be acquired, and this, at the most, does Inot exist two months. _____

METABOLISM OF SKI SPORT.

FROM time immemorial the Scandinavian peopleshave used skis (Icel. scidh, a piece of wood) to preventthem from sinking in the snow on their journeys inthe long Northern winter. Ski-ing as a sport isabout 60 years old in Norway, whence it was intro- Iduced into Switzerland about the vear 1900. Thelast ten years have seen an enormous developmentof ski-running as a form of winter amusement, andit has now become the object of serious study byphysiologists. Prof. A. Loewy has recently pub-lished in the Schzceiz. med. ZVocherzsehrift the resultsof a study undertaken by him to ascertain whetherthe sensation of ease experienced by the ski-er neces-sarily involves a diminished output of energy, andwhether ski-ing is superior to walking from an

economic point of view, as Liljestrand and Stenstromhad previously found to be the case with skating andL. Zuntz with cycling. An unskilled ski-runnerobviously expends a great deal of unnecessary energyin various balancing and other movements of thebody, whereas the movements of an expert are notonly fewer in number but are also easier and freer,giving the impression that less energy is needed tocover a given distance with skis than without them.To verify this impression an estimation of the

gaseous exchange is essential. The only observa-tions on the subject hitherto published are some notesby Liljestrand, whose experiments, even though madeunder specially favourable conditions rarely realised,showed a higher value both for CO 2 output and foroxygen consumption. Prof. Loewy’s idea was toascertain the exchange taking place under " natural

"

-i.e., ordinary-conditions both with and withoutskis, on ftrIll and on soft snow, on level and on roughground. The subjects of the experiments were

healthy schoolboys of from 13 to 17 years of age, allof whom were expert ski-ers. The apparatus usedwas that devised by Zuntz, with which the volumeof inspired air could be read off, and the expired aircollected and subsequently analysed. A table isgiven showing for each of the nine individuals testedthe volume of air breathed, the CO output, theoxygen consumption, and the percentage of oxygenincrease with and without skis on level ground andon a slope. The figures give a good idea of theinfluence which the condition of the ground exerciseson the breathing, but the most important pointbrought out is that in every case the volume of airbreathed is enormously increased-up to 47 percent.-with the use of skis. Similarly, while theoxygen consumption is much increased when walking Ion snow without skis as compared with walking onfirm snow-free roads-17’3 c.cm. as compared with13’5 c.cm.-yet with the use of skis it rises still moremarkedly, the figures in this particular series reachinga minimum of 20’6 and a maximum of 31’S c.cm. In

answer to the possible objection that the height ofDavos (1500 m.), where the experiments took place,might have some bearing on these results, Prof.Loewy points out that all the subjects of the experi-ment were living at this altitude, and were theretorewell acclimatised.

It is thus quite clear that from the point of viewof expenditure of energy ski-ing offers no advantageover walking ; and although in ski-ing on levelground there appears to be invariably an associatedsensation of ease and lightness, Prof. Loewy hasconclusively demonstrated that this subjective sensa-tion bears no relation to the actual output of energyrequired, the apparently easier movement involvinga considerably greater consumption of energy. Thevalue of ski-ing, however, lies mainly in the greaterspeed attainable by its means, and in the possibilityof moving with comparative safety over ground thatwould otherwise be dangerous, both these advantagesamply justifying the popularity of the sport.

THE OFFICIAL CONTROL OF DISPENSING.

IN a circular (No. 462) just issued under the Saleof Food and Drugs Acts the Minister of Health drawsthe attention of local sanitary authorities to certainsuggestions which he has received from the Society ofPublic Analysts with regard to the sampling of pre-scribed medicines. These are to the effect:

(i.) That the inspector be instructed, prior to dividing thesample into three parts, to mark, in the presence of thevendor, the height the contents reach in the bottle in whichthe medicine is originally supplied to him by the vendor.That the bottle so marked be submitted to the analyst inorder to enable him to determine the total quantity ofmedicine supplied.

(ii.) That the analyst and the medical officer of health beboth consulted as to the type of prescription it is desirableto use for the purpose of checking the accuracy of dispensing,and that, in the event of any substantial inaccuracies beingdisclosed by analysis, both these officers be consulted as tothe desirability of instituting proceedings.The object of the first suggestion is to enable the

analyst to ascertain the total quantity of each of theingredients (including the water or other " vehicle ")present in the medicine. If he receives only a portionof the sample, representing an unknown fraction ofthe whole, he is only able to ascertain the relativepercentages of the several ingredients ; but if he isalso provided with information as to the total quantityof the medicine dispensed he can then reduce thetotal amount of each of the ingredients as suppliedby the chemist. These particulars will obviously beof importance to the authority in considering whataction it should take in regard to a medicine whichhas been inaccurately dispensed. The second sugges-tion is in accordance with the practice already largelyadopted by local authorities. It is clearly desirablethat, where a sample of medicine is taken for thepurpose of checking the accuracy of dispensing, itshould be so chosen as to be capable of accurateanalysis. It is also desirable in considering whetheror not proceedings should be taken under the Sale ofFood and Drugs Acts that proper regard should bepaid both to the degree of accuracy obtainable inthe analysis of the article in question and to themargin of error allowable in ordinary dispensingoperations. ____

THE DIAGNOSIS UNIT ON ACTIVE SERVICE.

IN the Jouroal of the Royal Army Medical Corpsfor December, 1923, Dr. Philip Manson-Bahr concludeshis useful contribution on Laboratory Diagnosis in theTropics and Sub-Tropics in War Time. In this paperhe calls attention to the value of diagnosis units con-sisting of one medical officer, two special orderlies,and two drivers. Such units have the advantage ofextreme mobility ; two of them, in fact, moved toDamascus in 1918 with the cavalry. They are self-contained, possess their own transport, and are ableto perform essential work at a rapid rate. During thesummer of 1918 six units in Palestine examined morethan 40,000 slides of blood for malarial parasites,

39discovering a percentage of subtertian infection whichvaried at the different stations from 2 to 16 and whichshowed a dramatic rise in the month of October.Malaria simulates other diseases so closely as to bealmost undiagnosable without the help of a labora-tory -. at one of these diagnosis units it was foundthat 11 out of 15 cases segregated as dysentery and30 out of 45 cases diagnosed as influenza were reallydue to subtertian malaria. For the purpose oftraining the personnel to deal with the diagnoses ofmalaria and dysentery, 7 officers and 16 orderliesattended a course, lasting six weeks, held some distancebehind the line. Within this time it was possible torender the officers, and in most cases the men as well,familiar with the appearance of normal blood cells andthe various stages of the malarial parasite, although,of course, the actual diagnosis was made in each caseby the officer in charge. The advantage of mobilehorse-drawn diagnosis units of the kind described byDr. Manson-Bahr is apparent from his article andshould certainly be borne in mind in any futurecampaigns. By means of such rapid diagnosis themechanism of evacuation is accelerated, the work ofthe field laboratories alleviated, and the routine ofthe casualty clearing station lightened.

MEDICAL BIOMETRY.Prof. Raymond Pearl in his "Introduction to I

Medical Biometry and Statistics," has attempted Ito write an introduction to the practice of statisticswhich shall appeal to the medical reader having nopreliminary mathematical knowledge and no primaryinterest in mathematical lines of thought. With thisend in view, mathematical investigations are almostwholly excluded from the volume, the fundamentalconcepts being developed on experimental lines ; an

excellent example of this is the chapter on correlation,where the passage from no correlation to perfectcorrelation is exhibited by a series of experiments.In the first chapter, the author, having dealt withpreliminary definitions, lays down the followingpropositions :-

1. That there is no inherent reason why medicine in everyone of its phases should not ultimately become in respect ofits methods an exact science, in the same sense that physics,chemistry, or astronomy are to-day exact sciences. 2. Thatthis goal will be reached in exact ratio to the extent towhich quantitative methods of thought and action are madean integral part of the training in every sort of medicine.3. That no number or figure can be said to have any finalscientific validity or meaning until we know its probableerror, the " probable error " being the measure of the extentto which the number will vary in its value as the result ofchance alone.

Prof. Pearl gives an historical sketch of the pioneerwork done by Graunt, Sussmilch, Quetelet, and Farr.In speaking of the latter, he makes full use of Dr.M. Greenwood’s article published in our columns2in 1921, which he characterises ass the best existingbrief estimate of the significance of Farr in the historyof medicine." Following chapters describe the rawdata and methods of presentation. The author’saccount of the Hollerith system will be found veryhelpful since few private students have theopportunity of seeing or using the machines. Prof.Pearl passes to an exposition of rates and ratios anda short account of life-tables. In speaking of shortmethods of life-table construction, reference mighthave been made to Part II. of the Supplement to the75th Annual Report of the Registrar-General, whichdescribes the method of Dr. E. C. Snow, much the bestavailable. Prof. Pearl next discusses the concept of" probable error " and related notions of probability.In Chapter XIII., the measurement of variation isstudied; in the next two, correlation; the workconcludes with a short account of simple curve fitting.It will be seen that the book covers much ground,and, in our judgement, its author has successfullyaccomplished his task. It is natural and right thatin his choice of examples, Prof. Pearl should have

1 London: W. B. Saunders Company. 1923. Pp. 379. 25s.2 Medical Statistics, THE LANCET, 1921, i., 985.

had the needs of American students chiefly in mind,but this fact will not prevent English public healthstudents from profiting fully by a study of the book.Since, under the new regulations of the GeneralIMedical Council, a less superficial acquaintance withthe elements of vital statistics is demanded of candi-dates for the D.P.H. than before, the book shouldenjoy a wide circulation ; we know of no other likelyto be equally useful to the medical student. Theliterary style is agreeable and the expression of opinionon disputed points temperate. with the possible excep-tion of a footnote on p. 224, where the animadversionsupon Mr. J. lI. Keynes’s treatise might have beenexpressed more courteously. We gather from thepreface that Prof. Pearl has in mind to publish asequel to this book ; should it be as well writtenas the present volume, advanced students will incurthe debt of gratitude which this book imposes uponbeginners. ____

RECOVERY BRANCHES OF HOSPITALS.

Iw7 reporting last week the meeting of King Edward’sHospital Fund for London, brief mention was madeof the report of a committee on the " recoverybranches " of London hospitals. This report waspresented by the chairman of the Hospital EconomyCommittee, Mr. Leonard L.. Cohen, who remarkedthat the apparent cheapness resulting from the lowcost per bed at the branch was largely illusory. Fourof the large London hospitals have branches whollyor largely devoted to recovery work as distinct fromconvalescent work. These are the Elizabeth GarrettAnderson Hospital for Women (at Barnet), the LondonHospital (at Reigate and now also at Mitcham), theRoyal Northern Hospital (at Southgate), and St.George’s Hospital (at Wimbledon, partly recoveryand partly convalescent). There is no doubt thatconvalescent patients benefit by the better air and thecomparative quietude of their surroundings at theserecovery hospitals ; there is the further advantagethat the number of cases passed through the parenthospital can be thereby increased. It was also thoughtat one time that the average cost at the branch wouldbe much lower than at the hospital, but in respectof this financial saving the advantage appears tohave been exaggerated, and any hospital which estab-lished a recovery branch on the strength of thisargument might find itself involved in unexpectedfinancial liability. The resemblances between therecovery branch and any other addition to the bedaccommodation of a hospital are far greater than thedifferences. The addition of a recovery branch,moreover, concentrates in the parent hospital a

larger number of patients who need expensive methodsof diagnosis and treatment, thus enabling fuller useto be made of a highly specialised staff and apparatus.The wider adoption of the system should properlybe regarded as a form of hospital extension, theadditional beds merely being at a distance instead ofon the hospital site. It is in fact an economical andefficient method of extension.

THE COMMON COLD.

I " THE amount of absenteeism in large business and

; industrial establishments due to minor illnesses is,

seldom appreciated until the facts are thoroughly reviewed." This is the opening sentence in a recent’

Statistical Bulletin of the Metropolitan Life Insurance’

Company of Xew York (Vol. No. 11), where an. analysis is made of the loss of time due to the " common- cold " among 6700 clerical employees at the company’s central office. During the year ending July 28th,’ 1923, no fewer than 282-1 common colds, involving’

disability for work, were reported to the company’s’ medical staff, infection occurring at a rate of 421 per: 1000 employees for the year. We are not told what degree of streaming nose determined the disabilityJ for work or whether the risk of infecting others counts

more in New York than it does here as an excuse forabsence. Th average number of days of disabilityper person on the pay-roll for the year was 0-9, and