1172 NOISE AND ITS CURE.

phases of the pandemic, a result in general agreementwith that of PEARL. Dr. VAUGHAN next considersthe history of influenza between 1893 and 1918 andgoes carefully into the date of first appearance in 1918.He is inclined to trace the origin of the pandemic toAmerica and to attribute its dispersiveness and viru-lence to movements of individuals and masses fromone part of the world to another, whereby the partlyadapted parasites become planted, as it were, intonew soil, and the original equilibrium is disturbed-quoting the actual words of THEOBALD SMITH. Theresults of a sampling inquiry, similar to but moredetailed than that undertaken by Dr. J. NivEN and the IMinistry of Health, resemble those of the Englishinvestigators, but Dr. VAUGHAN had materials for aconsideration of racial and occupational susceptibility.The latter revealed no significant selection ; as to theformer it would seem that the Irish suffered less thanother races-a contrast to their high mortality andmorbidity rates from tuberculosis. Evidence of a rela-tion between overcrowding and attack rate was hardlymore striking than in England, but the followingfigures are remarkable : Of 360 persons occupying thesame bed as a patient, 166, or 45-2 per cent., wereinfected ; of 303 occupying the same room but notthe same bed, 59, or 19-5 per cent., were infected ;of 1064 members of the family of a patient but notbelonging to one of the two previous categories, 273,or 22’3 per cent., were infected.On the important subject of immunity, Dr. VAUGHAN

was led to think that previous attack conferred noprotection against the 1920 recurrence, a conclusion Icompatible with the results of the English inquiry,from which some protection against an autumnattack appeared to be conferred by the summerattack of 1918. Both sets of observations agree thatthe absence of any enduring immunity is an importantfactor in the explosiveness of primary influenza. The

monograph ends with an. appeal for further study.Influenza will surely return, Dr. VAUGHAN writes; hegives his reasons for asserting that there will be mildepidemics within the next few years, that lateranother pandemic will arrive, and that after thiswill come pandemics in succession. This is not;an assertion made for flesh-creeping purposes, buta deduction from observation. In 1918, as in

1889, we were caught unprepared; let us do ourutmost to prevent the recurrence of the tragedy;to delay is to lose the valuable informationgained during the last two years. The futureis not without well-grounded hope, but success

will not be achieved until we have a much deeperunderstanding of the epidemiology of influenza. Wethink that the results reported by Dr. VAUGHAN,together with those of the Ministry of Health, justify.a conclusion more definite even than these words,convey. It is clear that influenza is in a different- cpidemiological class from that which contains small-pox and typhoid and that it has affinities with typhus.on the one hand and pneumonic plague on the other.Small-pox and typhoid are epidemic diseases which,wholly apart from any general sociological factors, canbe absolutely controlled. Their complete control is

sadly impeded by ignorance and incompetent or

selfish local authorities ; the intellectual problemitself has been solved. Typhus and plague are

in a different class. Of the former we may predicatewith certainty that it will always become epidemicwhen the general standard of life has fallen to a

critical value; of the latter we can say that a lowstandard of life, plus an unknown x, must be realised.The optimist hopes that influenza is more nearly akinto plague than to typhus, and that the x may be

unmasked and prove to be a something which we cancontrol here and now. The pessimist, focussing hisattention upon the known factor, will be of opinionthat a sinking standard of life, underfeeding, unem-ploymeiit, overcrowding-conditions now charac.

terising so large a proportion of the inhabitants of

Europe-must sooner or later bear fruit which eventhe epidemic intelligence service desiderated by Dr.VAUGHAN will be unable to nip in the bud.

Noise and its Cure.NOISE is a serious evil in industrial communities.

Continuous exposure to loud noises may lead to asense of weariness that impairs working capacitymore quickly than docs severe muscular fatigue. Itthus tends to lower output and so to raise the cost ofproduction. From the economical point of viewnoise may therefore be regarded as exercising thesame malign influence upon production as inefficientmanagement, poor light, bad ventilation, or exces-sively long hours. This was, in brief, the messageof Prof. H. J. SPOOLER’S Chadwick Lecture deliveredat Blackburn on Xov. 21 st-to combat the noise

plague, whether in our city streets or in our work-shops and factories, and we are grateful to him forinitiating a public movement for its removal. AsDr. DAN McKENZiE has pointed out in " The City ofDin," civilisation is noise, the more it progressesthe noisier it becomes, and lie has pictured Nature’sdesperate remedy of producing a human race devoidof hearing in order to protect the brain from thedamaging effects of overwhelming auditory stimuli.The fact is that while noise may be tolerated, if notignored, by healthy people at their best, the majorityare not in a condition of bodily and nervous healthto resist the irritation and consequent wearinessinduced by a long continuance of loud noises. It isnot only the naturally hypersensitive CARLYLES whosuffer, for few long-distance travellers by rail are

altogether exempt from a fatigue which is probablydue as much to the incessant bombardment of thebrain by massive auditory stimuli as to any otherfactor. Over and above the effect of noise upon the

general nervous system, there is the deleteriousinfluence exerted directly upon the hearing-organ ofworkers in noisy occupations ; and the list of occupa-tions causing noise deafness at the present day is along and increasing one. Hitherto, it must be con-fessed, the general attitude towards the evil of din,whether in the workshop or in the street, has been toregard it as inevitable, and to seek mitigation by thepersonal use of antiphones or ear-plugs.But-and it i5 well to state it frankly-din,

even in an industrial milieu, is not inevitable.We need go no further than to the modern motor-carto realise that when quietness in machinery, esseii-

tially noisy in its working, is of marketable value, thegenius of engineering will ultimately succeed in

supplying that quality. The difference between thesmoothly running, almost silent automobile of 1921and its fussy predecessor of 1900 is a measure of thepreference given by purchasers to a noiseless vehicle.Now if, as Prof. SPOONER suggests, quietness in a

factory can be shown to have an economic value, thenwe may reasonably anticipate that it will be forth-coming. Even now " quiet running" " is beginningto figure more and more in the advertisements ofengines other than those of the internal combustiontype. Fortunately, apart from intentional reductionof noise, the natural evolution of modern engineeringis tending in the direction of electric transmission in

1173THE PHENOMENON OF D’HERELLE.

place of the old-fashioned noisy rotating shafts andbelts. To enforce the abolition of unnecessary dinProf. SPOONER calls for an improvement in the existinglaws. Public opinion has already led to some

advance. We need submit no longer to the nerve-racking key-bugles of beanfeasters or the shrill

whistling of commissionaires for taxis. But no publicauthority can yet prevent the screeching of a steam-saw in the vicinity of dwelling-houses. To those whosuffer thus, only a civil action at law is open with allits costly delay. But progress under stress of eco-nomic pressure may prove more prompt than legalenactment. Prof. SPOONER considers the advisa-

bility of fixing a limit of permissible noise, for whichpurpose a unit, or standard of noise would be neces-sary. It might be difficult to find such a standard,although in general it would be fair to regard as

"noise" any sound in street or workshop whichnecessitated the raising of the conversational voicewithin a few yards of the source of the sound. To

replace a test sound so variable as the human voice,a noise-producer of a certain definite intensity couldbe devised, the inaudibility of which by normal earswithin the stated distance would constitute thelimit of permissible sound. But physical details maysafely be left to the ingenuity and resourcefulness ofthe scientific engineer, once he has been givenclearly to understand that civilisation is no longer toconnote noise.

The Phenomenon of d’Herelle.IN 1915 F. W. TWORT1 described the occurrence of 1

spontaneous lysis of micrococci derived from calf 1

vaccinia, and attributed the phenomenon to fermentaction. The same phenomenon was described inde- 1

pendently by D’HERELLE in 1917, and the latter’s ’persistent investigations and constant advocacy of aninteresting explanation of the facts observed has

brought the subject into great prominence throughoutthe world. ]Briefly, the facts elucidated by DIHFRELLEare these. If an emulsion of a stool from a case of

dysentery be filtered through a Chamberland filterthe clear bacteria-free fluid obtained is capable ofdissolving B. dysenteri((’ Shiga, in vitro. Suchextracts differ in their activity, the less active onesonly destroying a certain number of the organisms,whilst the more active ones procure the completesolution of a whole culture. A still more strikingfact follows : such lysed cultures contain the activeprinciple in large amounts, so that when a trace ofthe solution obtained in the first experiment is addedto a second normal culture of Shiga’s bacillus this alsoundergoes lysis, and a trace of this solution will

reproduce the phenomenon in yet a third culture, andso on indefinitely. Only living bacilli undergo lysis ;dead cultures are not affected. These, in the main,Were the first facts elucidated and they remain

undisputed. The lytic phenomenon is attributed byD’HERELLE to the presence of a filter-passing, ultra-microscopic living virus, which is an obligatoryparasite upon the bacterial body, and is capable ofcultivation only in the presence of such organisms ;it undergoes no increase in ordinary culture-media.Since these facts were made known, the subject hasbeen much broadened and all sorts of subsidiaryphenomena have been brought into prominence. Ithas been shown that the lytic substances may be foundin other situations than the intestinal contents, andthat even when coming from this source they are not

1 THE LANCET, 1915, ii., 1241.

specific-that is, substances lytic for Shiga bacillimay be found in persons not suffering from dysentery.It has also been shown by J. DUMAS that similarsubstances may be obtained from earth and somewaters, and by J. BORDET, also from leucocyte-containing peritoneal exudates. The interpretationof the phenomenon has been a matter of activediscussion and three main explanations have beenput forward. Firstly, the contagium-vivum theoryof D’HERELLE ; secondly, the view of T. KABESHIMA,who believes the lytic agent to be an enzyme, basingthis opinion upon the fact that solutions maintaintheir activity for years, and also that the principlecan be extracted by acetone ; such an extract willinitiate lysis, which can then be propagated in series.The third view is that supported by the authority ofBORDET, who has sought an explanation on develop-mental grounds and believes that a new strain ofbacteria is developed, under the conditions of theexperiment, which is susceptible to autolysis, and thatit is the presence of the autolytic products whichcauses a similar modification in subsequent genera-tions of bacteria, thus enabling the phenomenon tobe propagated; in short, that bacteria in undergoinglysis produce the environment conducive to thedevelopment of an autolytic strain. BORDET has pro-duced the D’BLEBELLB phenomenon by using extractsfrom the peritoneal fluid of a guinea-pig which hasreceived an injection of micro-organisms. Thesedifferent views have given rise to a good deal ofcontentious literature ; much of this is difficult tosift as the experiments adduced are by no meansconclusive and the discussion occasionally degeneratesinto a series of formal contradictions. It has also beenshown that under the influence of the lysin manycultures divide into two types, one of which transmitsthe lytic principle-and is BORDET’s autolytic strain-whilst the other is resistant to lysis and does not transmitthe property. These strains differ from one another,and from the " normal " parent strain, in certain oftheir properties. There is apparently a process ofselection, by which a small minority of resistantorganisms are enabled to establish themselves as atrue-breeding type in a culture in which they werepreviously swamped by a majority of the sensitivestrain. These results appear similar to those ofJ. A. ARKwRiGHT, who by a different method ofselection was able to split dysentery cultures intoseparate strains. As regards the phenomenon oflysis the most attractive explanation appears to bethe conception of an unorganised lytic enzyme whosecontinued transmission may be regarded as an exampleof the autocatalysis ; the freeing of the catalytic enzymeby the actual process of lysis, just as in the hydrolysisof an ester the acid set free serves to accelerate thereaction. The statement that the rate of the reactionincreases as it proceeds falls in very well with thisview. D’HERELLE,2 in the face of all criticism, hasmaintained his theory of a living bacteriophagium.In reviewing the work which has been done upon thissubject we are impressed by its importance from manypoints of view. It has certainly brought to lighta type of bacteriolysis quite different from thatdescribed by PFEIFFER, and is full of suggestion withregard to immunity and therapeutics. It has longbeen becoming evident to bacteriologists that theideas current in the last decade, as to the fixity of thecharacters by which they identify and define species.must sooner or later go by the board, to give way toa much broader conception whose limits are thelimits of physiological variation, within which thecharacters of any given organism may change.D’HERELLE’S work exemplifies the complexity of

many of the processes occurring in connexion withbacteria, and whatever the final explanation ofthese phenomena may be, we are indebted to himfor his consistent exposition of them and for thestimulus which his views have given to bacterio-logical research.

2 Comptes Rendus de la Soc. de Biol., 1921, vol. lxxxv.,No. 30, p. 767.