An analysis is given of the serological tests performed over a period of 15 months with viral, rickettsial and leptospiral antigens. The analysed material is made up of about 9400 tests performed on 4036 samples of serum obtained from 2430 patients and 536 animals.

The incidence of the various diseases, the distribution of the positive results according to diseases, and the height of the specific titres, as well as the height of the residual titres found in the material, are discussed and analysed in detail.

The procedure for the preliminary screening of the material, as well as the methods used in performing the different serological tests, are described and discussed.

A few examples of possible double infections are quoted, namely atypical virus pneumonia with influenza, and influenza A with B.

An analysis of the results of 1723 tests performed with influenza antigens on 909 samples of sera is presented.

The results obtained from testing about 1000 sera for cold agglutinins and 482 sera for MG agglutinins are discussed in detail.

Some cases of liver affections showed a marked rise in titre both of cold agglutinins and of MG agglutinins.

The serum samples, numbering about 1050, drawn from normal persons or patients suffering from infections other than Q-fever, all gave titres lower than 1/64 when tested with Q-fever antigen, except the sera of four persons who were probably cases of recent inapparent infection.

The geometrical mean of the titres found in sera drawn from acute Q-fever patients between the 29th and 60th days of their illness was 1/355. Of the 500 sera from various animals, 100 from sheep and eight from cows had titres of 1/8 to 1/64 against the Q-fever antigen.

Thirty-four sera have been positive when tested with the soluble antigen of both the epidemic and the murine types of typhus but no serum has given a higher titre with the murine type antigen than with the epidemic type antigen. Of the thirty-four sera tested with both antigens the titres obtained with the epidemic antigen were higher than with the murine antigen in 28.

The results obtained with 417 sera tested with the mumps antigen, and with the 222 sera tested with the lymphocytic choriomeningitis antigen are reported and discussed in detail.

Great individual variation has been observed in the time of appearance and rise and fall of the Paul-Bunell titres. Consequently, it is advised that early and frequent blood samples should be obtained from patients who are suspected to be suffering from infectious mononucleosis. On the basis of the results of 316 Paul-Bunnell tests it is suggested that a titre of 1/20, if preceded or followed by a negative serum sample, should be taken as conclusive evidence of infectious mononucleosis.

3080 human and 164 animal sera have been investigated for the presence of antibodies to various types of leptospirae. In both human and animal sera antibodies have been found most frequently against L. sejroe and L. pomona.

The results of a few tests performed with toxoplasma antigen are mentioned briefly.

We wish to express our gratitude to all our colleagues in Belgrade and other parts of the country who have provided us with information and additional samples of blood when requested, in particular Prof. K. Todorowich of the Infectious Diseases Hospital, Belgrade, and Drs Lj. Vuksich, M. Morelj, B. Arsich, D. Mehl and R. Papo of the Army Medical School, Belgrade.

We wish to thank Dr R. Djorich of the Infectious Diseases Hospital, Belgrade, for the supply of material for testing for atypical virus pneumonia and aseptic meningitis, and Dr Ž. Perishich for help with our cases of infectious mononucleosis. Mrs Martha Milivojevich gave valuable assistance with the complement-fixation tests and with the compilation of material for this report.

Guinea-pigs are suited to colony management, whether for breeding or maintenance, and single cages are only necessary when experimental or other requirements demand them.

Floor pens are extravagant of space and open to criticism on grounds of hygiene.

Wire floored pens, in batteries of four tiers, have many advantages, both in economy and hygiene, and are compatible with excellent health and breeding performance.

Certain details in the design of such batteries are important; among them being the size of mesh of the wire floor, the avoidance of corners and ledges where soil can accumulate, and the observance of convenient dimensions.

I first saw this method developed by an accredited guinea-pig breeder, Mr Ashton Poole, who has since given up breeding. Although the present battery is a far cry from Mr Poole's pens, the method is the same, and the unblemished health record of his very large stud over a period of some years was impressive. I am glad therefore to acknowledge my indebtedness to him.

The multiplication rate of blue-tongue virus in suckling and adult mouse brains has been determined. The first cycle of virus multiplication appears to take 8–12 hr. both in fully susceptible sucklings and in adults which suffer an inapparent infection with this virus.

Antigens suitable for complement-fixation tests have been made from suckling mouse brains and from eggs infected with blue-tongue virus.

A potent immune serum has been obtained from mice immunized by repeated intraperitoneal injections of blue-tongue virus in suckling mouse brain.

Attempts, with negative results, have been made to demonstrate interference with virus multiplication by virus from eggs incubated at 38·5° C. and by virus from adult mouse brains.

We are grateful to Dr R. Alexander for his helpful and critical interest in this work and to Mr G. S. Turner and Dr G. Selzer for their able and willing assistance.

The Virus Research Unit is financed by the South African Council for Scientific and Industrial Research and by grants from the Nkana-Kitwe and Chingola Poliomyelitis Research Funds.

Nose and throat swabs were collected from 2413 healthy children aged 2 weeks to 14 years and examined for Streptococcus pyogenes. The children came from different social levels in three boroughs in Middlesex.

Standardized carrier rates were used to compare the individual effects of age, borough, family age, family size, sex, social class and tonsils on the nose and throat carrier rates.

Community life appeared to facilitate the spread of streptococcal infection: young children aged less than 5 who attended nurseries had higher carrier rates than those of the same age who did not attend day-nurseries. The highest nasal carrier rates were found in the 3- and 4-year-old children attending the day-nurseries. The degree of crowding within the community units did not appear to affect the rates.

The three boroughs had significantly different carrier rates.

Boys were more often carriers than girls.

The unstandardized carrier rates were highest in the lowest social class but this could be explained by the differences in the age, sex and borough distribution of the children sampled in the three social classes, and by the fact that tonsillectomy was, on the average, undertaken later in the lower social classes than in the higher. When these factors were allowed for by standardization, there was no residual difference which could be attributed to social class or housing.

Children with tonsils were more often nose and throat carriers than children who had had their tonsils removed; this was true for all ages, for each of the three boroughs and in each social class.

We are indebted to the Area Medical Officers in Enfield, Southgate and Willesden for their co-operation in the planning of the survey and to the staff in the schools, day-nurseries and clinics where the swabbing was carried out. We are most grateful to Dr P. Armitage for help with the statistical methods and to Miss Eileen Cole for much help with the computing.

1. When detached portions of the chorioallantoic membranes of normal fertile eggs are examined in the dark-field microscope spherical and tubular cytoplasmic protrusions are seen to develop from the margins of the cells and to become detached from them. This is probably a normal physiological phenomenon which occurs to some extent in the intact egg.

2. Similar cell protrusions occur from chorioallantoic membranes of eggs infected with influenza virus. The phenomenon appears to be more pronounced in the infected egg than in the normal egg and in particular tubular cytoplasmic protrusions are much more frequent in the infected egg than in the normal.

3. Tubular cytoplasmic protrusions may fragment into small spherical particles or may contract into filaments. All types of cell protrusion become detached from the cells and undergo contraction in size probably as a result of loss of water. The infective elementary bodies and filaments present in the allantoic fluid of eggs infected with influenza virus are derived from the cells in this way.

4. It is concluded that the infective particle of the influenza virus is a fragment of the cell cytoplasm and consists of a closely aggregated mass of virus protein enclosed in cell membrane.

The author is indebted to Prof. W. T. Astbury and Dr R. Reed for the electron photomicrographs reproduced in this paper.

Suppose that λ is the average density of virus particles per unit volume. If x is a dilution of this and unit volume is applied to an egg (or plate in other problems) the probability that the egg remains sterile is

provided that if a particle is present, it will infect the egg. To make a dilution assay we choose dilutions x1, …, xm (m levels) and apply these to n1, …, nm eggs. If these result in r1, …, rm sterile eggs we can estimate λ by maximum likelihood. The theory has been given by Barkworth & Irwin (1938), and full references to work on this problem will be found in Finney (1952). If we plot the quantities r1/n1, …, rm/nm against x1, …, xm we get a set of point whose fit to the curve (1) can be tested by a χ2 test. In a number of situations, however, it is found that (1) does not give a good fit. The estimation of λ is then completely invalid. In the present paper we consider why this happens, what types of curve may be fitted to the data and what they imply, and we also give a simple rapid test for such data fitting an exponential curve.

Factors affecting the formation and destruction of sulphide in the Thames Estuary have been discussed. Measurements of oxidation-reduction potentials show that the effect of oxygen in the water on conditions in deposits of mud is limited to the surface layer. The rate of formation of sulphide increases with temperature, doubling approximately for each 10° C. rise. Reduction of sulphate to sulphide will occur at temperatures as low as 5° C., but even at 25° C. is inhibited by traces of dissolved oxygen. Mud in suspension in the estuary can produce as much sulphide as compact layers of similar mud which might be more anaerobic.

Oxidation of sulphide in the Thames Estuary is shown to be of a purely chemical nature; the rate of oxidation, when oxygen is present, is increased by the presence of suspended matter and iron. In the Thames Estuary, however, the rate is limited by the rate at which oxygen enters the water.

Much of the experimental work described in this paper was carried out by Miss A. Laird, Mr A. E. Sutton and Mr R. B. Peel of this Laboratory. The paper is published by permission of the Department of Scientific and Industrial Research.

A number of workers have shown that antibodies to the influenza A viruses which are demonstrable in the sera of normal adults undergo periodic fluctuations in titre related to epidemic occurrence of the disease. The rise in antibodies accompanying infection and demonstrable by neutralization, agglutination-inhibition and complement-fixation tests is used as a method of diagnosis which is admitted to be of greater sensitivity than actual recovery of virus from the throat. Studies of the population during an epidemic have also revealed the existence of subclinical infection with rise in antibodies comparable to that occurring in those suffering clinical illnesses. But surveys of sera from large samples of the population show no general upward shift in antibody levels unless an actual epidemic occurs (Martin, 1940). The studies made by Francis, Magill, Rickard & Beck (1937), Hoyle & Fairbrother (1937), Rickard, Lennette & Horsfall (1940) and Martin (1940) also indicate the relative impermanence of the enhanced antibody levels consequent upon an epidemic. A relatively rapid decrease in antibody is shown both by the neutralization and complement-fixation tests during the 3–6 months after an epidemic and then a slower fall occurs until the next epidemic again causes a rise in titres. There have, however, been relatively few studies on large samples of populations situated in different geographical areas before and during an outbreak.

1. The production of soluble antigen in the chorioallantoic membranes at 6 hr. can be used to measure the infectivity of influenza virus preparations.

2. Intracellular virus is much more infective when tested by soluble antigen production at 6 hr. than when tested by conventional methods.

3. It is suggested that intracellular virus differs from extracellular because more virus particles per cell are required to initiate infection.

The author is greatly indebted to Dr L. Hoyle for his advice and encouragement throughout this work. Mr G. Field gave valuable help with the mathematics.

1. The growth in synthetic cream of certain pathogenic bacteria may be inhibited by two methods:

(a) By limiting the ingredients to cooking fat or other fatty material, excluding margarine or butter, emulsifying agent such as methyl cellulose, sugar and salt. The cream must not then be left in contact with confectionery from which nutritive material may be absorbed. This last condition renders the method impracticable as a means of control.

(b) By the addition to synthetic cream, including those containing milk and egg, of a bacteriostatic agent such as hydrogen peroxide.

2. Contaminants may grow in emulsified fats in the absence of protein. These are probably lipolytic organisms which are able to utilize the products split from the fat. Organisms such as coagulase-positive staphylococci, Salmonella paratyphi B, and Bacterium coli, tend to die out within 24 hr. or after a few days in creams lacking protein.

3. The concentration of H2O2 necessary to inhibit the growth of test organisms is dependent on the ingredients of the cream. In the presence of butter, milk and egg yolk at least three times the concentration of H2O2 is necessary as when emulsified fat without added protein is used. The suggestion is made that concentrations of H2O2 from 0·005 to 0·02% should be added to all commercially produced synthetic cream, the actual concentration used depending on the constituents of the cream.

4. To prevent the growth of contaminating organisms in commercially produced synthetic cream, H2O2 should be added immediately after pasteurization and cooling when the bacterial count is still low. Even comparatively high concentrations of H2O2 will not inhibit or control the growth of bacteria already present in large numbers.

5. The inhibiting power of 0·012% of H2O2 remained effective in a fat-emulsion cream and also in a laboratory cream containing margarine, egg and milk for 3 weeks at + 4 and 20° C.; at higher temperatures of storage the stability of the oxidizing agent is doubtful.

6. Since synthetic cream is exposed to so many different sources of contamination, particularly in the bakery, and since there is no method of controlling the growth of pathogenic organisms that have gained access to it other than by the addition of a bacteriostatic agent, it is strongly recommended that the present regulations on preservatives should be altered to allow the addition of H2O2 in suitable concentration to synthetic cream.

We are grateful to all those who have helped in the supplies of material, and in particular we wish to thank the Public Health Department, St Pancras Town Hall; Mr E. Capstick, United Dairies Ltd.; Mr J. Valentine Backes, President, Bakery Allied Traders' Association; and also Messrs Bakcos Catering Supplies Ltd., A. Bellamy and Co. Ltd., Farma Cream Products Ltd., Krema Ltd., Malga Products Ltd., Ramsay, Braddon and Co. Ltd., Quality Foods Ltd., Sunnyside Products Ltd., Unicream Ltd., and Vitacream Ltd.

We are indebted to Mr L. Bailey for his technical assistance.

The present communication completes the series of war-time studies (Shewan, 1945, 1953) on the dehydration of fish, and is concerned with certain aspects of the bacteriology of the small-scale commercial production of dehydrated fish (herring, kipper, fresh and smoked cod), carried out in the summers of 1944 and 1945 by the Ministry of Food in a factory at Aberdeen. During these commercial trials, samples of fish were taken each day for a routine bacterial count and examined for the presence of food-poisoning pathogens. Several other tests were made from time to time in order to elucidate special points, such as the adequacy of the cooking procedure and the occasional incidence of high bacterial counts. The following is a summary and review of these results; with some recommendations for future production.

1. The normal agglutinin (n.a.) for Trichomonas foetus found in all normal adult cattle has a titre of 1:48 to 1:96. N.a. appears to be specific for T. foetus and cannot be absorbed by other flagellates such as T. vaginalis or even completely by the heterologous serological variety of T. foetus itself. The n.a. appears to be a native constituent of the serum and not to be induced by an exogenous antigen.

2. The n.a. passes into the serum of the calf from the maternal colostrum during the first 24 hr. of life. The elimination of the passive n.a. and the development of the autogenous newly formed n.a. in the calf are traced. The passive n.a. disappeared from the 17th to the 55th day and the autogenous n.a. began to appear as a rule from the 35th to the 60th day and was fully established by the 63rd to the 113th day.

3. The elimination of the maternal, induced antibody acquired passively from the colostrum took place logarithmically. The rate measured by the half-life ranged from 14 to 20 days, but in one animal which took a very large amount of colostrum it was 57 days.

4. The intramuscular injection of T. foetus antigen into very young calves up to 4 weeks old induced no antibody. When the doses were relatively small the animal produced antibody to antigen given at a later period. When a very large amount was injected in this early period the subsequent capacity to respond to the same antigen but not to other antigens was seriously impaired.

The personal encouragement of Prof. H. G. Lamont and the support afforded by the Ministry of Agriculture, Northern Ireland, are gratefully acknowledged.

An attempt has been made to establish the nature of the ringworm flora of Birmingham, comprising: (1) the species encountered; (2) their relative concentration; (3) their distribution.

A marked increase in the number of cases due to fungi of animal origin has been demonstrated.

It has been shown that the main reservoir of infection in the city is centred upon Sparkbrook and Balsall Heath, with a rather smaller focus in the Hockley–Lozells area.