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"came several years after that of the influenza wave.He points out also that clinical cases of encephalitiswere absent from the records of the pandemic ofinfluenza of 1889-92. As to aetiology cerebro-spinalfever is due to the meningococcus, and the researches,,of Dr. Flexner and his collaborators at the RockefellerInstitute have demonstrated that poliomyelitis is dueto a filter-passing virus. Epidemic encephalitis isprobably due to a similar virus. Dr. Flexner reviewsthe work on the herpes virus and concludes that it isunlikely that simple herpes and epidemic encephalitishave a common aetiology. Accumulated evidenceindicates that all these nervous epidemics are man-borne infections spread chiefly by way of the respira-tory tract. Dr. Flexner expresses no definite opinionon post-vaccinal encephalitis, holding that its exact.aetiology is still obscure.

PURER RIVERS.

THE first report of the Joint Advisory Committee onRiver Pollution is a businesslike and unanimousdocument. The law, it seems, is not inadequate toprevent contamination, but the law is not enforced.Serious and avoidable pollution exists, says the.Committee, partly because the jurisdiction of thevarious administrative authorities is confined to aparticular area only, partly because the bodies which.ought to enforce the law have a number of other morepressing duties to discharge, and partly because thegame-keepers are also poachers. The prevention ofpollution should be in the hands of an authority.exercising jurisdiction over the river as a whole(including its tributaries) at any rate so far as non-tidal waters are concerned. The creation of riversboards or joint committees for this purpose isalready possible under the existing law. Under,Section 14 of the Local Government Act of 1888, theMinistry of Health can set up such bodies by ProvisionalOrder on the application of the county councils andcounty borough councils concerned. The reportrecommends that this existing provision be speciallybrought to the notice of all these councils. There isreason to believe that the necessary applications tothe Ministry of Health would then in many cases bemade, and an important step would have been takentowards the ideal of purer rivers. The rivers Thamesand Lee are controlled by special statutory ConservancyBoards with which the report does not propose tointerfere. The powers of these two bodies, so vitalto the water-supply of the metropolis, are alreadygreater than the ordinary powers given by the RiverPollution Acts. Indeed the methods employed bythe Metropolitan Water Board for treating Thameswater have, both in respect of finance and purification,been so successful as to encourage recourse to riverwater for domestic supply, and have been officially- praised in the recent annual report of the Ministry.of Health. Elsewhere, it is recommended, the RiversBoard areas should be big enough to make sure thatskilled officers can be employed, and not so big asto make it impossible for the chief officers to keepthemselves thoroughly informed of the existence ofany pollution and the best means of prevention.,Since effluents and local conditions vary, the problemis best dealt with by local effort, though centralresearch must be pressed forward and results madegenerally available. The report is evidently impressedby the efficiency and economy of the three group-bodies which are already at work-the Ribble Joint.Committee, the Mersey and Irwell Joint Committee,and the West Riding of Yorkshire Rivers Board.Though these bodies have power to take legal pro-ceedings against offenders, legal process apparently isresorted to only in extreme cases. In most instances,advice and persuasion are found effective, and itseems to be happily the fact that the relations betweenthe Rivers Boards, fishery boards, local authorities, andmanufacturers are cordial and mutually helpful. It isobvious that this is not the time when Parliament canbe asked to pass fresh legislation which may placefurther burdens upon industry. The figures of cost

for efficient treatment of seBvage in particular districtsare sometimes extraordinarily high. Nevertheless, itis reassuring to find that much can be done under theexisting law, that needless, wilful, and remediablepollution can be prevented without interfering withhard-pressed industries, and that there is evidence of akeener popular interest in the purity of our riversthan heretofore. Wider changes in the law and amore closely courdinated study of the problems ofriver purity, land drainage, and water power resourcesmay come some day. Meanwhile the Joint AdvisoryCommittee makes some simple proposals which can betackled forthwith. As appointed by the Ministries ofHealth and of Agriculture and Fisheries, the Committeeis fully representative of local authorities, water andrivers boards, and the manufacturing, fishing, andagricultural interests. Its report carries the greaterweight on this account, especially as it has achievedunanimity. ____

THE PATHOGENY OF ANGINA PECTORIS.

ANGINA has always been somewhat of a stumblingblock to the morbid anatomist, the autopsy findingsare so varied and at times so inadequate. A number ofdistinguished physicians, including Allbutt in thiscountry, Vaquez in France, and Wenckebach inVienna, have found in aortitis an explanation of thesymptoms, but aortitis could only act (if thne wens)a temporary rise in blood pressure during the attack—B"/an assumption which is by no means proved.Mackenzie’s theory that the pain is attributable toexhaustion of the heart muscle is also unsatisfactory.Anatomical evidence in many cases is in favour ofcoronary disease being the determining factor, butthis is not invariably present, and in recent yearsthere has been a tendency to abandon the anatomicalin favour of a physiological explanation which willaccount for the varied post-mortem findings. Theevidence in support of the physiological hypothesisthat angina is due to anoxæmia of the heart muscleis well presented in a recent paper by C. S. Keeferand W. H. Reznik, who, following Heberden’soriginal description, define angina as a conditioncharacterised by pain of a paroxysmal nature provokedby an increase and relieved by a diminution in thedemand made upon the heart. They add that thediagnosis of angina should always imply the likelihoodof sudden death. The similarity of the pain in anginato that in intermittent claudication, as well as theexperimental evidence that voluntary muscles whichare made to contract when their blood-supply isdefective are easily fatigued, and that the contractionis accompanied by pain, strongly supports this hypo-thesis. Further, it is well known that anoxaemia, isan important predisposing cause of ventricularfibrillation. This fact will account for the frequencywith which sudden death is liable to occur in thesecases. In affording an explanation of the persistenceof the pain in coronary thrombosis the physiologicalhypothesis is equally satisfactory; for in that con-dition, unless the anastomoses be sufficient to com-pensate for the occluded artery, the anoxaemia is

permanent and leads to infarction.

THE PARATHYROIDS AND BONE UNION.

MUCH attention has been paid of late to thesignificance of the parathyroids in metabolism, butexperimental work has not yet thrown much light onclinical application. The work of Collip and othershas demonstrated that an extract can be obtainedfrom these glands which can overcome the syndromeof tetania parathyreopriva with its attendant lowblood calcium. The injection of active parathyroidextracts may in animals even lead to fatal resultsaccompanied by very high blood-calcium values.The older observation of Koch 2 that methyl-guanidine appears in the urine of parathyroidectomiseddogs, and of Paton 3 and his co-workers that the

* Arch. Intern. Med., 1928, xli., 770.

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injection of guanidine and methyl-guanidine in.animals leads to tetany-like symptoms gave rise tothe theory that the parathyroids formed a part of thedetoxicating mechanism of the body. The view moregenerally held to-day is that the parathyroids exertsome at present unknown influence on calcium rneta-bolism. Efforts have consequently been made to workout their relationship to bone metabolism, particularlyfrom the clinical aspect of the healing of fractures.It was as long ago as 1907 that Erdheim 4 first

reported experiments on rats which showed that,.as a result of parathyroidectomy, the teeth lost theiryellow transparent appearance, and became white andopaque. He noted also that there was a diminished.and delayed deposition of calcium in the dentine, andthat the enamel was decreased or thin or lacking.Hohlbaum 5 and others confirmed these results as well.as Erdheim’s further contention that reimplantationof the glands restored the teeth to normal. Other- observations of Erdheim’s,6 however, to the effect- that parathyroidectomy caused delay in the healing.of fractures were not substantiated by Hohlbaum, orby Jovane and Vaglio, or by Korenchewsky.8 Thelatter pointed out that Erdheim’s experiments werevitiated by lack of dietary control. Other workers,however, have supported Erdheim’s conclusions.()gawa,9 for instance, investigated the relation ofthese glands to the healing of fractures, and reportedthat union was slower after their removal. Dieterich 10

also found that this operation delayed callus formation,though X ray and histological examination provedthat otherwise the process was normal in every respect.Morel11 found in cats a marked retardation in theformation of callus after parathyroidectomy, bu onlyin young animals and not in adults.More recent work has, however, called in question

:some of the older experiments. Gates and Grant(1927)lz have demonstrated fairly conclusively thatsubtotal removal of the parathyroids creates a

deficiency which is rapidly compensated by hyper-trophy of the remaining tissue, and that the bloodcalcium is restored to normal in a week to ten days.Anything short of complete removal therefore is nota reliable test of under-function of the tissue afterthis period of time. -Until recently few observationshave been made as to the effect of parathyroid extractson the metabolism of bone, apart from scatteredstatements in the literature referring to its use inabnormal cases. There is some doubt, however, asto the activity of the extracts employed in thesecases, for it is only since Collip isolated the active eprinciple of the gland that definitely active prepara-tions have been available. Morel, however, in 1909,claimed that subcutaneous injections of a parathyroid.extract in young animals produced bones of twice thethickness of those in controls, regardless of the amountof calcium in the food. Recent experiments with’Collip’s extract do not support his work. Fine andBrown, working at Harvard, have published 13 theresults of their experiments on bone repair underthe influence of the extract, and their conclusions arein startling contrast to Morel’s. They conclude thatthe clinical use of the extract for delayed bone unionis not based on any sound principle, can do little ifany good, and in fact may do harm. The number oftheir experiments, however, was small. The wholequestion of the relationship of the parathyroids tobone metabolism is still sub judice, and requires more’extensive research before any definite conclusions canbe arrived at.

References.—1. Collip, J. B.: Jour. Biol. Chem., 1925, lxiii.,395. 2. Koch, W. F. : Ibid., 1912, xii., 313 ; 1913, xv., 43.3. Paton, D. N. : Quart. Jour. Exp. Physiol., 1917, x., 203 ff.4. Erdheim, J.: Sitzungsb. Akad. Wissensch. in Wien, 1907,cxvi., 311. 5. Hohlbaum, J., zu Biedl: Innere Secretion,second edition, vol. i., 109. 6. Erdheim, J. : Frank. Zeitschr.f. Path., 1911, vii., 175, 238, 295. 7. Jovane, A., and Vaglio,R., zu Biedl : Innere Secretion, second edition, vol. i., 109.8. Korenchewsky, V. : Jour. Path. and Bact., 1922, xxv., 366.9. Ogawa, S.: Arch. f. Exper. Path. and Pharm., 1925, cix.,83, 300. 10. Dieterich, H.: Arch. f. kiln. Chir., 1925, cxxxvi.,388. 11. Morel, L. : Compt. Rendus Soc. de Biol., 1909, lxvii.,780. 12. Gates, F. L., and Grant, J. II. B. : Jour. Exper. Med.,1927, xlv., 115, 150. 13. Fine, J., and Brown, S. : New Eng.Jour. Med., June, 1928, p. 932.

STANDARDS OF ATMOSPHERIC POLLUTION.

IN the thirteenth report of the Advisory Committeeon Atmospheric Pollution, to which reference hasalready been made, there is an interesting suggestionof the possibility of setting up limits or standards ofpermissible pollution. In the report the cities havebeen classified according to a scale of increasingpollution into four classes-A, B, C, and D. A tablefor the years 1914-15 to 1926-27 indicates a tendencytowards improvement in many places, but unfortu-nately this improvement, as we have pointed out, israther in the moderately clean than in the very dirtycities, which show little change. The importantpoint is, however, that a step has been taken towardssetting up some standard of clean air. The placesclassified A may be called clean, while the D’s arecertainly dirty. With the information now becomingavailable it should shortly be possible to take a mostimportant step from a public health point of view-namely, to set up a standard of clean air, a conditionof the air of a city which is to be aimed at and isreasonably attainable. So far only a standard fordeposited impurity has been suggested ; the limits ofpermissible suspended dust still remain to be fixed.Those who are engaged with these standards wouldfind their work simplified if reliable information couldbe obtained as to the minimum requirements ofsunlight, and especially of ultra-violet light, for

healthy living. This would be a first step towardsfixing limits of smoke pollution which could not beexceeded without detriment to the health of a city.

DARWIN’S KENTISH HOME.

AN announcement made at a meeting of theGeneral Committee of the British Association inGlasgow in respect of the destination of Down House,Darwin’s home in the county of Kent, is of realinterest to the medical profession, when we rememberthe fundamental revolution in our philosophy andendeavour that has followed upon Darwin’s work.Mr. Buckston Browne having acquired the propertyfrom Prof. Charles Galton Darwin, F.R.S., grandson ofthe great naturalist, has transferred its possession tothe British Association under the most liberal condi-tions, and with an endowment for its maintenance andpreservation. Mr. Buckston Browne’s public spiritand generosity which have before now obtainedpublicity in spite of his retiring manner of doinggood, are marked, as on the previous occasions, byconditions which are calculated to extract from hisopen-handed action the fullest benefit. He hasassured the Council that he will make himself immedi-ately responsible for the whole gift, and that while acommittee will have to consider the details, he willalso furnish an endowment fund, bringing his donationup to the splendid sum of from £12,000 to £15,000.Sir Arthur Keith, President of the General Committeeof the Association, has suggested that out of theendowment fund money should be expended uponthe foundation of a prize to be given every secondyear for the best contribution to biological knowledge,to be awarded by the Council, and to be known as the"

George Buckston Browne Prize." For the momentDown House serves as a, nrivate school, but as soonas the property can become an effective gift to thenation Mr. Buckston Browne desires the house to beopen every day of the week between the hours of10 and 6 without charge, while the grounds of thehouse, which are of considerable extent, he intendsshould be employed for the benefit of science. Further,certain of the rooms in the house, particularly that inwhich so much of the " Origin of Species" waswritten, he proposes should be furnished as nearly aspossible in accordance with their old appearance, andalready this project is in process of fulfilment throughthe cordial help of the Darwin family, without which,it should be said, the new ownership of the propertycould not have been obtained. Charles Darwin’s study