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In 1946, as a registrar in clinical pathology at Guy’s, I wasasked by Dr F. A. Knott to do a z.N. on material from a suspectedhydatid cyst. So that I might know what to look for, he showedme acid-fast hooklets in a film of sputum. He had heard of themethod several years before from an Irish technician who workedfor the Clinical Research Association in London. Earlier in 1946,at Guy’s, wanting confirmation of my beginner’s diagnosis of aninspissated hydatid, I had asked Dr S. J. De Navasquez’s opinion:he agreed that the picture in the haematoxylin-eosin preparationswas typical, but advised a z.N. in the hope it might show hooklets.Dr P. A. Gorer, overhearing this, mentioned that Prof. G. W.de P. Nicholson had taught him, at Guy’s, that old hydatids wereoften misdiagnosed through failure to do a z.N. or through con-centrating on the search for tubercle bacilli and thereby over-looking the much larger acid-fast hooklets.During the 1939-45 war, I had a patient with a dried-out

hydatid in the liver. The lobectomy specimen was sent to DrW. W. Woods, at the London Hospital, the consultant in histo-pathology to the Royal Navy. In his report he mentioned that thediagnosis had been confirmed by the demonstration of acid-fasthooklets.

In 1936-37, while a student in Belfast, I kept notes (whichI still have) of Dr N. C. Graham’s lectures on microbiology,including his comment that acid-fast staining shows not onlytubercle and leprosy bacilli but sometimes keratins and chitins,rhinosporidial sporangia and parts of metazoa, such as echino-coccal hooklets. Prof. J. S. Young mentioned this characteristicof the hooklets at a post-mortem demonstration during the

pathology course in Belfast that year.In 1898, my father did a post-mortem in the Kasr el Ainy

Hospital in Cairo on a patient with a hydatid cyst in a tuber-culous lung. I still had the z.N. preparation a few years ago: theechinococcal hooklets were admirably shown as well as thetubercle bacilli.

’

The earliest date in this sequence is in 1887. It could not havebeen much earlier, for acid-fast staining was not known until1882. 2

In 1887, on March 24, in Aberdeen, my father attended oneof Prof. D. J. Hamilton’s classes in histology. His notes, whichI have, include: "Specimen. Echinococcus tumour. Liver.Teenia echinococcus v. Siebold. Hydatid. Logwood. Farrant.Also as for T.B. It was first thought to be a syphilitic gumma ora tuberculous tumour. The Ehrlich-Weigert method shows notubercle bacilli. Instead there are beautifully shown the hooksremaining from the scolices of the ta;nia. These are not de-colorised by the nitric acid."

I would add only that the hooklets of Echinococcusgranulosus may be as strongly acid-and-alcohol-fast as anytubercle bacillus, or they may be acid-fast and not alcohol-fast, or only weakly acid-fast, or not acid-fast at all. Whenweakly acid-fast or not acid-fast in paraffin sections theymay yet be strongly acid-fast in films of matter from thesame specimen. Their acid-fastness may be evident only ifthey are decolourised with weak acid or if they are stained byone of the methods developed to demonstrate less stronglyacid-fast organisms, such as lepra bacilli. When a hydatidhas been effete for long enough the hooklets may disappear:specific immunofluorescent staining may then still indicatethe nature of the lesion.

Northwood,Middlesex HA6 2AS. WILLIAM ST CLAIR SYMMERS.

PREVENTION OF INTRAUTERINE

RUBELLA

SiR,-Babies born deaf, blind, or backward because ofrubella infection are as handicapped as many damaged bythalidomide; and should be as rare.The present policy is to try to protect, by immunisation

at school or in the puerperium, young women and thosewho have just had a baby. Mothers outside these groups willcontinue to bear affected children for years to come, andit is difficult to explain to them why they should be left at

1. Ehrlich, P. Dt. med. Wschr. 1882, 8, 269.2. Ziehl, F. ibid. p. 451.

risk. At the least, all potential mothers should be encouragedby advertisement to find out, from a few drops of blood onfilter-paper, if they are susceptible. Those who are cancourt natural infection before pregnancy or enter purdahduring it; or demand immunisation.

Epidemiologically we should be content to count theaffected babies, if any, born to the immunised, and notaccept a terrible and unwitting sacrifice from some of thecontrols. Mass screening will be expensive (perhaps 10patients a week for a year for each general practitioner),but the reward will be great.

The Warren, Downton,Wiltshire. T. H. HUGHES-DAVIES.

TINNED BABYFOODS

SIR,-Dr Leach (April 14, p. 825) is under a mis-

apprehension if she thinks Heinz recommend that the dietof a three-month-old or 11 lb. baby should include a

weekly total of 24 cans of Heinz babyfoods.According to the Heinz guide to infant feeding, From

Milk to Mixed Diet, a booklet written under the super-vision of a consultant paediatrician and widely distributedby the company, mixed feeding can generally start withsix teaspoons of strained food when the baby has reachedabout 11 lb. Once this routine has been established, thetypical diet of a baby between 11 lb. and 13 lb. wouldinclude two half-cans of strained foods at the 2 P.M. feed-a total of 7 cans per week, not 24.Dr Leach apparently assumed the higher figure from

her interpretation of the Heinz advertisement which hasbeen running in women’s magazines. The advertisementinvites mothers to write for the booklet From Milk to

Mixed Diet, and states " Heinz Strained Menu from 3months old or 11 lb. up to 6 or 7 months, Heinz JuniorMenu from 6 or 7 months to 18 months ". It then givesexamples of two weekly menus, one headed " strained "and the other " Junior ". *The example given for strained foods has in fact been

taken from the middle of the strained foods age range of3 to 6 or 7 months and relates to a 4-5 month-old baby.This fact is not stated, however, and, to prevent similarmisunderstandings, future advertisements giving a menuexample will identify the specific age-group to which itrelates.We agree with Dr Leach’s general point that babies are

often started on mixed feeding at too early an age and arethen given more food than is desirable. Our advice,which seeks to reflect a consensus of medical opinion, hasconsistently warned against the dangers of overfeedingand has emphasised the need for babies to develop at anatural pace on the basis of a properly balanced diet.

COLIN CHAMBERLAIN,General Manager,

Marketing Product Group,H. J. Heinz Co. Ltd.

Hayes Park, Hayes,Middlesex.

** * Mr Chamberlain sent a copy of his letter to DrLeach, whose reply follows.-ED. L.

SIR,-Although I am glad to hear that Messrs Heinzdid not intend to recommend 24 cans of their strained foodsper week for infants of 3 months, and that they propose toalter their advertisement to make this clear, I am appalledto find that they do seriously recommend such a diet forinfants of 4-5 months. If 7 cans is right at 3 months, can24 be right 6 weeks later ? Such a rate of increase bears norelation to the infant’s probable length/weight increase.The booklet to which Mr Chamberlain refers suggests a

total milk intake of 15 oz. per 24 hours at 4-5 months and

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a period at night of approximately 14 hours unfed. Let ushope that most infants will explain, vociferously, that thisis just not on.Normally the beginning of mixed feeding is regarded as

an addition to milk feeding, filling the slowly increasing gapbetween the amount of milk the infant can comfortablyhold and his hunger. Heinz’s booklet takes an oppositeapproach: speaking of babies weighing 11-13 lb.

" when

baby is taking all six teaspoons of Heinz Strained Food

you should decrease the bottle feeding by 1 oz. of milk ...once baby is taking half a can of dinner and half a can ofpudding you should then stop giving the breast or bottlefeed and give a drink of orange juice instead...." MessrsHeinz seem to turn the usual process upside down, pre-senting their cans not as an addition to milk but as apreferable substitute.

I must reiterate my previous point. We have no evidenceto suggest that at these ages and weights solid foods arepreferable to milk. What little evidence we do have in thematter suggests that too much extra protein and too manyextra calories are both undesirable.

3 Tanza Road,London NW3 2UA. PENELOPE LEACH.

PRIVATE PATIENTS AND THE N.H.S.

SIR,-Following recent publicity concerning consultantsand private patients in N.H.S. hospitals, perhaps somefigures would help to put the situation into proper per-spective. During the whole of 1972, in this typical regionalhospital group, out of a total of 27,383 admissions, 124were private patients. To put this into more simple terms,45 out of every 10,000 patients were private-that is,0-45%.

Department of Anæsthesia,Royal Infirmary,

Blackburn, Lancs BB2 3LR. MERTON SEIGLEMAN.

VITAMIN C AND COLDS

SIR,-In the randomised double-blind clinical trial infour Irish boarding-schools recently reported by ProfessorWilson and Dr Loh (March 24, p. 638), they comparedthe effects of prolonged administration of vitamin C (inone of two doses) and of placebo on the incidence andseverity of the common cold.The following is a summary of their incidence data:

The three types of cold are not clearly defined in the text nor is it clearwhether overlap between the three types exists. Actual numbers ofchildren and of colds are not stated.

These data show a tendency (albeit not highly statisticallysignificant) for the children who received more vitamin Cto suffer more colds. Since it is hardly plausible to supposethat vitamin C actually causes colds, this useful studyshows (even more clearly than simple equality between therates would have shown) that vitamin C in doses of 0-5 g.per day is not protective against the common cold.The authors also report and discuss data on the duration,

severity, and total intensity of the colds that did occur.

As with the incidence data reproduced above, the average(over the three cold types and the four schools) percentagechange in each index was positive; the treated groupsfared slightly worse. However, when, as in their paper,48 different statistical tests are performed, a few misleadingtests of significance are to be expected. None of their 48tests were significant at the 1% level, and of those sig-nificant at the 10% level 4 were in favour of vitamin Cand 5 were against. We feel that the authors were unwiseto draw any conclusions from these 4 mild significancetests. In our opinion, their data are most satisfactorilyexplained if vitamin C is wholly without effect on the

frequency or severity of colds.

LEO KINLENRICHARD PETO.

Department of the RegiusProfessor of Medicine,Radcliffe Infirmary,Oxford OX2 6HE.

SIR,-In the important study of Professor Wilson andDr Loh, we searched in vain for the number of subjects inthe experimental groups. Though the authors might con-ceivably expect us to accept their significance tests fordifferences found, without disclosing the sample sizes, theysurely could not ask us to accept the absence of groupdifferences without our knowing the power of the study todetect differences. They thus confound the vitamin-Ccontroversy.

School of Public Health,University of Minnesota,

Minneapolis,Minnesota 55455, U.S.A.

HENRY BLACKBURNJEAN CANNER.

SCREENING FOR VITAMIN-C STATUS

SiR,—The letter by Dr Harris and Mr Ajose (March 24,p. 671) prompts me to describe our considerable experienceof screening for vitamin-C status in this laboratory. LikeDr Harris and Mr Ajose, we found that dichlorophenol-indophenol is unreliable for estimating urinary ascorbic acid(A.A.) because of the liability of A.A. to oxidise quickly todehydroascorbic acid and diketogulonic acid. We found that2,4-dinitrophenylhydrazine is more satisfactory, since itreacts only with the oxidised products of A.A. metabolismand therefore measures total A.A. concentration. 1,2 Thiswould make estimation of 24-hour urinary A.A. concentra-tion after a loading dose of vitamin C a more reliablescreening-test. Since the renal threshold for A.A. is about1-4 mg. per 100 ml., the fluid intake and the timing of aspecimen of urine after a loading dose of vitamin C willdetermine the concentrations of A.A. in a particular speci-men.3 Another factor is the circadian periodicity of leucocyteand plasma A.A. concentrations.4,5 The concentration ofA.A. in the urine will vary from time to time during the dayas the blood-level fluctuates, more A.A. appearing in theurine when the blood-level exceeds the renal thresholdthan when the blocd-level is at its lowest during thecircadian cycle. Since the blood-A.A. concentration is at itspeak during the early hours of the morning and after anovernight fast without water, the first urine specimen in themorning shows less fluctuation and is a reliable estimationof vitamin-C status if 24-hour urine cannot be collected. 2

A quick screening-test for vitamin C has been describedby Cheraskin and Ringsdorf.6 It involves timing with astop-watch the disappearance of a drop of N/340 2,6-

1. Loh, H. S., Wilson, C. W. M. Int. J. vit. nutr. Res. 1971, 41, 90.2. Loh, H. S., Wilson, C. W. M. Lancet, 1971, i, 19.3. Burch, H, B. Ann N. Y. Acad. Sci. 1961, 92, 268.4. Wilson, C. W. M., Loh, H. S. Ir. J. med. Sci. 1969, 2, 396.5. Loh, H. S., Wilson, C. W. M. Int. J. vit. nutr. Res. 1973 (in the

press).6. Cheraskin, E., Ringsdorf, W. N., Jr. Int. Z. Vitaminforsch. 1968,

38, 114.