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are probably involved-a neurogenic and a vascular.Russek and his associates 9 10 have already shown thatthe reactibility of the blood-pressure, as judged by thecold pressor test, increases with age ; and Dock11 believesthat this increase is related to trophic loss of neuroneswith ageing. The vascular factor, however, is probablymore important, consisting of a progressive diminutionof elasticity of the aorta and its larger branches. This

change results in a higher systolic and lower diastolicpressure, whereas the neurogenic factor raises both systolicand diastolic. In other words, the neurogenic and vascularfactors have a summating effect on the systolic pressure,but opposing effects on the diastolic pressure.Two practical implications emerge from this study :

(1) the upper limit of normality for the systolic pressurein the elderly must be accepted as considerably above140 mm. Hg; and (2) in identifying essential hyper-tension emphasis must be laid on the diastolic ratherthan the systolic pressure. This latter view has been

gaining ground in recent years; Hines,12 for instance,suggested that only the diastolic pressure is of value inpredicting the subsequent development of hypertension.It has also been generally accepted for many years thatthe prognosis in the elderly is much better with systolichypertension than with diastolic hypertension. WhatM only now being elucidated is the " normal " blood-pressure for that increasingly large section of the

community over the age of 50 years.

THE WHEELS TURN

THIRTEEN days at Geneva, from March 31 to April 12,were barely sufficient to dispatch the business of thethird session of the Interim Commission of the WorldHealth Organisation. The terminal scramble was partlydue to the commission’s failure to recognise that theyhad undertaken more than the secretariat could manageand partly to an inveterate tendency among somemembers to reopen questions already decided. Much

good work, however, was done, and some importantdecisions taken in a most cordial atmosphere, to whichthe member from the U.S.S.R., Dr. C. A. Kolesnikov,was a notable contributor. As the chairman, ’Dr. A.Stampar, remarked in his closing speech, no seriousdifferences of opinion were revealed and no voting wasnecessary. Of the 18 members 16 attended, Dr. I.Medved of the Ukraine and Dr. J. Togba of Liberia

being unavoidably absent-the former because of hisrecent elevation to the post of minister of health. SirWilson Jameson was present during the first week of thesession. Observers attended from the Uriited Nations,F.A.O., the International Children’s Fund, the Inter-national Refugee Organisation, the International CivilAviation Organisation, the Paris Office, the Pan-American Sanitary Bureau, UNESCO, and UNRRA.The most important task before the commission was

to balance the budget, since the decisions taken at thesecond session’ last November 13 called for an excess ofexpenditure over income of some 300,000 dollars. Bycareful pruning this was achieved, even with the inclusionof some new items, except for a necessary reserve of200,000 dollars, for which a further loan from the UnitedNations may be required. Among the new items anomission was repaired by providing for an expert com-mittee on tuberculosis, and experts on child welfare andnutrition, venereal diseases, infant mortality, andinfluenza are to be appointed. The commission approvedthe allocations of funds for field services, derived fromUNRRA, according to the requests from countries formissions, fellowships, visiting lecturers, and medicalliterature, and also approved the agreements concluded

9. Russek, H. I. Amer. Heart J. 1943, 26, 398.10. — Zohman, B. L. Ibid, 1945, 29, 113.11. Dock, W. N. Y. St. J. Med. 1945, 45, 983.12. Hines, E. A. jun. J. Amer. med. Ass. 1940, 115, 271.13. Lancet, 1946, ii, 799.

with the governments of Greece and Ethiopia for fieldmissions.The commission did not see entirely eye to eye with

the observer from UNESCO, Mr. J. Needham, F.R.S., onthe apparent encroachments of that body into the

territory of health, but it was decided to set up a jointcommittee on the organisational level to define theboundaries. A joint committee on nutrition with F.A.O.will also be set up, to which the International Children’sFund may be conjoined. The negotiating subcommitteeon relations with the Pan-American Sanitary Bureau ,-

reported considerable progress, which, as it failed to

satisfy some members and went too far for others, wasprobably the best practicable mean.

Technical matters were chiefly dealt with by thecommittee on epidemiology and quarantine and by thenew committee on priorities. Studies are to be under-taken by the secretariat on postvaccinal encephalitis,the " immune reaction " in vaccination, and immunisa-tion against influenza. A meeting of a technical com-mittee of the Interim Commission is now taking place inCairo to consider revision of the clauses of the 1926and 1938 conventions dealing with the Mecca pilgrimage,and on April 21 the expert committee on malaria metin Geneva. The expert committee on lists of causes ofdeath and morbidity met in Ottawa last month.

If we look back over the twelve months since thetechnical preparatory committee met in Paris in March,1946, the progress made is seen to be gratifying andunprecedented. A constitution for a World HealthOrganisation has been signed by 63 nations. Aninterim commission to carrv on the urgent and statutoryduties pertaining to world health has been workingeffectively for the-past six months. The Paris Office,the Health Organisation of the League of Nations, andthe Health Division of UNRRA have been in practiceabsorbed, and their work carried on without serious

interruption. Considerable progress has been made withthe integration with the Pan-American Sanitary Bureau..Ten States-members of the United Nations and 3 non-members have ratified the constitution, and the progressreported of other ratifications is such that the necessary 26will almost certainly be obtained before the end of the year.

A PIONEER OF SOCIAL DYNAMICS

ONE of the clearest and simplest formulations ofKurt Lewin, whose obituary we publish this week, washis distinction between the scientific concepts of Aristotleand Galileo. In dynamics Aristotle emphasised thenature of the object : he held that a stone fell to the

ground because it was " earth " and had therefore to gotowards the earth. Galileo, on the other hand, madephysicists pay more attention to the object’s relationto -its environment. According to Aristotelian thoughtthe environment played a part by

"

disturbing " theprocesses which follow from the nature of the objectconcerned ; but in Galileian thought it is the concretewhole, which comprises the object and the situation,that determines the dynamics of the event defined:that is to say, an object is always in and part of itsenvironment-an obvious notion but one with far-

reaching implications if taken literally and always applied.Its application to medicine is plain. We cannot

isolate a person from his environment. When we examinean individual we are also examining a part of a geneticand a social field at the same time, if our ways of thoughtare thorough. When a patient comes to us our trainingleads us to see an object with an extension in time :it begins as a speck smaller than a pin’s head, and endssome day as a life-size corpse. That speck grows byreason of forces in the cell and in the tissues in which it isembedded ; that embryo, that child, develops throughadolescence to adulthood and withers in old age : we

see on examination at any one time a small slice in that