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With regard to the protection of the nursing staff,since the beginning of 1922, every nurse has beenSchick tested on entry. During 11 months of 1922and the whole of 1923 only naturally immune (Schick-negative) nurses were allowed to work in diphtheriawards. Although this procedure afforded a verydrastic test of the value of the Schick negativereaction, it became necessary, in order that Schick-positive probationers might enter diphtheria wards,to produce active immunity amongst this group.At the present moment every member of the nursingstaff is either naturally immune, or has been, or is inthe process of being, actively immunised. In roundnumbers one-third of the nursing staff has been foundto be Schick-positive ; thus only one-third requiresactive immunisation if the validity of the negative

I’Schick test be accepted. The following figures are ofsome interest :-

In 1923 the four nurses who contracted diphtheriawere all Schick - positive probationers, who were

working in scarlet fever wards, and, in the well-knownmanner of junior probationers, contracted the diseasesoon after entry. There have been instances where Ihave thought that the test had failed us, but I havehad, on investigation and re-testing, to conclude thatthe technique or recording or toxin was at fault,and that the test itself is a true index of susceptibilityor otherwise to clinical diphtheria. In this beliefI am greatly supported by the critical human experi-ments of Guthrie, Marshall, and Moss. In myexperience, no indubitably negative Schick reactor hasever contracted clinical diphtheria as distinct from atransient tonsillitis associated with the presence ofmorphological diphtheria bacilli or a frankly " carrierstate.-I am, Sir, yours faithfully,

E. H. R. HARRIES,Medical Superintendent, Birmingham City

April 24th, 1924. Hospital, Little Bromwich.

E. H. R. HARRIES,Medical Superintendent, Birmingham City

Hospital, Little Bromwich.

To the Editor of THE LANCET.

SiB,—The points raised by Dr. C. W. Hutt in yourissue of April 26th were emphasised by myself twoyears ago in papers published in THE LANCET (1922,i., 312) and in Public Health (May, 1922). I pointedout that the age-groups which gave the greatestnumber of Schick-positive reactions exactly coincidedwith the age-period when the incidence of clinicaldiphtheria is most marked-viz., 2-5 years. Further-more, I suggested that the public health authorities,through their child welfare and school medicalservices, were in a position to test and immunisethat portion of the population most susceptible todiphtheria.The Schick test and toxin-antitoxin immunisation

constitute one of the most notable recent advances inthe sphere of preventive medicine, and the results,which are on record, obtained during the last tenyears in New York sufficiently demonstrate itsvalue. At any rate, it is not too much to say that itis possible that the thorough systematic adoption oftoxin-antitoxin immunisation against diphtheria wouldresult in a great yearly saving of child life. May onehope that, without more ado, those who specialise inpreventive medicine will use their organised servicesto employ an agent which is potent to preventdiphtheria ? I am, Sir, yours faithfully,

Bedford-square, W.C., April 28th. T. E. DICKINSON.T. E. DICKINSON.

1 Experimental Inoculation of Human Throats with VirulentDiphtheria Bacilli, J. Hopkins Hosp. Bull., 1921, xxxii., pp. 369-78.

AURAL VERTIGO.

To the Editor of THE LANCET.SiB,—Dr. E. Hobhouse in his interesting letter on

this subject, in your issue of April 19th, expressessurprise that in the recent discussion on vertigo atthe Royal Society of Medicine " no one pointed outthat perfect equilibrium is possible when the semi-circular canals have been completely destroyed orrendered functionless by disease or operation." Forequilibrium the labyrinths of the two sides should beequally active or equally functionless, and in themost typical cases of aural vertigo there is a unilaterallesion with preponderance of the sound labyrinthover the diseased one. The vertigo would probablycome to an end if the healthy labyrinth were renderedfunctionless to the same extent. This might beimitated to some degree by the administration of adrug capable of diminishing the sensitiveness of thehealthy labyrinth. Such a drug we have in quinine(and the salicyl compounds), and doses so small ashardly to affect the auditory part of the labyrinthcan produce the desired sedative effect on theequilibrial part. In proof of this I have treated manycases of aural vertigo from unilateral lesions of thelabyrinth with small doses, say one-half or even one-third of a grain of sulphate of quinine, almost invari-ably with relief from the vertigo. In proof that thisresult is due to a sedative action on the sound laby-rinth I have measured the length of time necessaryfor the caloric induction of nystagmus and found thatafter treatment by means of quinine the time necessarywas considerably longer than before and the relieffrom vertigo was due to the approximation to anequalisation of the action of the two labyrinths towhich I referred in my contribution to the discussion(THE LANCET, March 1st, 1924, p. 446).

I am, Sir, yours faithfully,JAMES DUNDAS-GRANT.

London, W., April 28th, 1924.JAMES DUNDAS-GRANT.

ANTILEUCOCYTOLYSINS.To the Editor of THE LANCET.

SiB,—I have read with great interest the articleby Dr. Ivan Manoukhin in your issue of Jan. 26th.The " self-defensive reaction " which he there describesin the treatment of malaria could, presumably, beused for other diseases. On one point I should likemore information, however, and that is the functionof the antileucocytolysins, and of the organ that formsthem-the liver-in the defences of the body. I

gather from the article that they have a defensiverole which comes into play at a later stage than thatof the leucocytolysins, but their mode of action atthis later stage is not made clear.

I am, Sir, yours faithfully,Thaba ’Nchu, S. Afr:ca, March 15th, 1924. C. LUNDIE.C. LUNDIE.

HYMENOLEPIS NANA AND H. FRATERNA.

To the Editor of THE LANCET.

SIR,-Joyeux, in 1920, after a survey of most ofthe evidence, arrived at the conclusion that Hymeno-lepis nana of man and H. fraterna of rodents, thoughapparently indistinguishable in all characters, both ofthe adult worm and of the egg, are yet two distinctphysiological species. More recently, however, twoJapanese investigators, Saeki and Uchimura, havedenied the validity of the experiments described byJoyeux, and affirm that it is possible to infect micewith H. nana eggs. The original papers of these twoJapanese investigators not being easily accessible, andthe brief abstracts available providing little or nothingof that detailed information which is so essential inthese matters, I have recently been enabled, by thekind hospitality of Dr. A. Bettencourt, to re-examinethe subject. Briefly stated, I conveyed to Lisbon57 H. fraterna-free mice, 30 of which I have fed onfresh H. nana eggs obtained from the stools of infantsin the hospital attached to the Instituto Camara