1. Considerable differences in antigenic efficiency are encountered among batches of (1) diphtheria toxoid, and (2) Cl. welchii (perfringens) toxins prepared under standardized conditions. These differences were revealed in the results of hyperimmunization of horses.

2. Such differences in antigenic efficiency in batches of diphtheria toxoid were also detected by means of injections into guinea-pigs. Two injections, each of 2 Lf doses, were given at an interval of 28 days, and the response measured by means of antitoxin titrations on bleedings taken 10 days later.

3. A general correlation was found between antigenic efficiency as measured by these two methods.

4. A method is described for comparing the affinity for antitoxin, of batches of diphtheria toxoid, by determining the test dose of mixtures containing 9 Lf doses of toxoid and 1 Lr dose of a fixed toxin. The greater the avidity of the antitoxin, the more toxoid entered into combination with it.

5. A correlation was found to exist between affinity for antitoxin and antigenic efficiency of toxoid, as measured both by the response of horses to hyperimmunization and the response of guinea-pigs to two spaced injections.

6. It is tentatively suggested that crude toxoids may contain molecules possessing varying degrees of affinity for antitoxin, due to slight steric structural differences.

1. Naturally occurring agglutinins to paracolon bacilli have been found in seven out of ten sera from non-immunized rabbits and in one anti-Salmonella and two anti-paracolon immune rabbits' sera after complete absorption with the immunizing strain.

2. The a antigen of Stamp & Stone, which is known to occur as a natural agglutinin, has been demonstrated in one out of nine paracolon bacilli.

3. Rabbits which before immunization show agglutinins to the immunizing strain or to an α antigen should not be used for the preparation of diagnostic antisera for intestinal Gram-negative bacilli.

1. Nineteen rabbit does were inoculated each with the whole blood of a buck to which they were later mated.

2. They were observed over a period of 10 months which included three pregnancies: (a) for the appearance and behaviour of anti-red cell isoanti-body in their sera; and (6) for the effect of such an antibody on the offspring, especially those inheriting a paternal red cell antigen incompatible with their mother's antiserum.

3. The does' antisera were examined for antibodies capable of directly agglutinating red cells and for ‘incomplete’ antibodies which might sensitize cells without causing agglutination. The latter were identified by an indirect antiglobulin sensitization test.

4. Nine does formed antibodies in their sera, six of these antisera directly agglutinated the appropriate red cells, but in three cases the antibodies were demonstrated only by the indirect antiglobulin sensitization test. Of the six antisera which directly agglutinated red cells three had antibodies which caused direct agglutination of red cells undiluted or in their lower dilutions, but in higher dilutions were shown to be capable of sensitizing cells without agglutinating them.

5. Four does, who had produced antibody in their sera, had between them seven litters in which the red cells of the young inheriting a paternal antigen incompatible with their mother's antiserum reacted to a direct antiglobulin sensitization test. This reaction is discussed and it is concluded that a positive direct antiglobulin sensitization test means that maternal isoantibody is attached to the infants' red cells. The offspring whose red cells reacted positively were, nevertheless, clinically normal.

6. A proportion of the young were killed at 3 days and 24 days old. A full peripheral blood examination was made and imprints taken from the liver and spleen. The bone marrow was also examined. Specimens were taken from liver, spleen, suprarenal, kidneys, femur, and, in some cases, brain for histological examination after an autopsy had been performed. Fifteen normal rabbits were similarly examined at 3 days old and four at 24 days old.

7. The range and average figures for the various haematological examinations made are given and the findings in the experimental animals compared with the normals.

8. A few differences were found between the experimental and the normal animals as a result of this experiment. The significance of these is discussed.

1. Anti-mallein sera produced in thirteen species of mammals (including man) and one species of bird have been examined by the haemolytic complement fixation test using guinea-pig complement, and by the conglutinating complement absorption test using pig, horse and cat complements. Two methods of fixation have been used and compared, namely, fixation for half an hour at room temperature and fixation overnight at 4° C.

2. The complement of the horse proved to be the most sensitive in nearly every case in demonstrating the specific antibodies in the different sera; in the few instances where it was not markedly the most sensitive it was for practical purposes the equal of any other complement used, independent of the method of fixation. This is clearly indicated in the text figures.

3. The effects of overnight fixation on the titres obtained with the different complements are discussed.

4. The sera of six fowls inoculated with mallein failed to show fixation of any of the four complements in the presence of the homologous antigen. The presence of immune bodies was demonstrated however by the Indirect Complement Fixation technique of Rice (1948b).

An antibiotic elaborated by Pfeifferella whitmori is described. This principle is active in vitro against the H37RV strain of Mycobacterium tuberculosis, but in several other respects closely resembles penicillin. It has given encouraging results in a small-scale therapeutic trial in experimental guinea-pig diphtheria.

Data are given showing the concentration of pure ozone required to inhibit the growth of, and to destroy, various micro-organisms when growing on agar, in nutrient broth, a synthetic medium, or simply suspended in water. The following is shown:

1. Different organisms vary in their susceptibility towards this gas. Achromobacter and Pseudomonas strains, such as occur on chilled meat, are the most resistant. On the whole, mould fungi are about as susceptible as bacteria.

2. Very much higher concentrations are required to arrest established growth than can be used if inoculation and admission of inhibitor are coincident.

3. Lower concentrations are inhibitory at lower temperatures. These results are ascribed to dissipation of the ozone by combination with products of bacterial metabolism. It seems that any factor which diminishes growth will augment the effectiveness of ozone.

4. Comparatively small concentrations (less than 10 p.p.m.) suffice to destroy bacteria suspended in water. Somewhat larger concentrations inhibit growth in a synthetic medium.

5. Still larger quantities (several hundred p.p.m.) are required in nutrient broth.

6. Nutrient broth treated with ozone will support little or no bacterial growth, due to change of pH, growth taking place slowly if the pH is restored to its original value. Inhibition of growth in such a medium is therefore a complex process depending in part upon the secondary effects of decomposition of the medium.

7. To kill them, bacteria require still more ozone (in some cases several thousand p.p.m.) if growing on agar. These results are ascribed to combination of ozone with the supporting medium.

8. When applied to organisms growing on food, combination with ozone not only spoils the food, but it makes it difficult to interpret the effect on the microbes in terms of the ozone applied.

9. The inhibitory concentrations are higher than humans can tolerate.

10. Ozone destroys the dehydrogenating enzymes of the cell, and it is suggested that its germicidal action may be partly due to interference with cellular respiration.

The work described in this paper was carried out as part of the programme of the Food Investigation Organization of the Department of Scientific and Industrial Research.

The following conclusions were drawn from these experiments with bovine group B streptococci:

1. A relationship existed between lethal power and the number of living organisms inoculated, and, therefore, the number of living organisms inoculated must be determined when the killing power of a strain is under investigation.

2. Equal doses of the same strain were likely to kill more mice, but less rapidly, when inoculated intravenously than when inoculated intraperitone-ally.

3. Virulence for mice might be related to serological type.

4. The disease caused by intraperitoneal inoculation of strain S 13 was a rapidly fatal peritonitis with concomitant bacteraemia.

5. The disease caused by intravenous inoculation of strain S13 was a fatal bacteraemia with a tendency for the streptococci to form dense clumps in widely separated tissues.

There were nearly 400 cases of gastro-enteritis in Brisbane from May to October 1947. About half represented the endemic level then prevailing, and the remainder formed a virulent epidemic, which was responsible for most of the deaths. Salmonella bovismorbificans was isolated from a sufficient proportion of these cases to justify the belief that it was the cause of the epidemic.

Of recognized infections with S. bovis-morbificans 77 % were in babies under 1 year old, 19 % in those 1–2 years old, and 4 % in older children and adults. The infection was most severe in the under-1-year-old group, and severity varied during the epidemic, reaching a maximum in August and thereafter declining steadily.

Nearly two-thirds of the infections were institutional.

Infants were found to be infective during the incubation period and also for periods up to 6 months after clinical recovery. Their faeces provided the greatest mass of infective material. Infections in older age groups were relatively unimportant in relation to the rate of epidemic spread, but significant secondary centres of infection developed in mice and cockroaches in the hospital wards.

The path of infection was traced from the faeces to the sinks and brushes used for cleansing soiled napkins, to mice and cockroaches which had access to the sinks, and to ward wash-basins and nailbrushes used by the nursing staff. Possible indicators of faecal contamination were found on nurses' hands, in ward kitchens, and in milk mixtures prepared for babies' feeds.

Control is believed to be practicable and to depend, first, on making medical officers and nurses aware of the dangers; and secondly, on improved ward hygiene, of which elimination of washing napkins in wards, reduction of contamination when changing napkins, rigid segregation of ‘clean’ and ‘dirty’ nurses, and improvements in food preparation and administration, are regarded as the most important.

1. Strains of Bact. coli and related bacteria possess a life cycle resembling that of Myxobacteria. The vesicular, resting nucleus is contained in a microcyst, which is formed by a process suggestive of sexual conjugation.

2. The microcyst germinates by the transformation of the resting nucleus into the chromosome-like bodies typical of active, vegetative cultures. These may be analogous to the chromosome complexes of yeasts. The period of germination of microcysts corresponds to the lag phase of cultures.

3. The nucleus remains permanently in the mitotic condition during the active, vegetative phase of growth, and reproduces by an asexual and a sexual method.

4. Older cultures may be transformed directly into microcysts or may first adopt a secondary, vegetative phase, in which the nucleus is in the form of a single, central body.

5. Microcyst formation differs from spore formation in that it lacks the obvious reduction processes associated with spore formation, upon which a few original observations are included.

An expectation of life limited to n years is properly defined by

to which the approximation usually used is

A survey of both the prevailing and the desirable conditions for housing small laboratory animals, with particular reference to rats and mice, is described. The data surveyed are confined to laboratories in Great Britain and include requirements of space, heating, ventilation and building construction, with such accessories as cages, feeding devices and other equipment.

The amount of clerical work involved, and the ramifications of the record system used, in an animal laboratory, are conditioned by the purpose for which the colony is maintained, and dependent upon how anxious its custodians are to control its size and guide its future. If, for instance, ease of operation and minimization of clerking is to be the overriding consideration one may secure a good supply of young rats by the simple process of allowing a flock of adult animals the freedom of a warm room containing bedding and food. One enters at intervals to clean and feed, and, eventually, to remove, for experimental work, those youngsters that look big enough to fend for themselves, taking care, at the same time, to leave a few of each sex to grow to maturity and guarantee the next generation. An occasional census of population and production is all that is necessary in the way of records.

A simple cubed diet is described, completely adequate to sustain rapid growth and intensive reproduction in mice and rats.

1. The use of compound cubed diets for monkeys is discussed.

2. Experiments are described which seem to show that a cubed diet, supplemented only by greenfood and water, can be completely adequate for growth and reproduction.

An outbreak of eighteen cases of pemphigus neonatorum in a maternity department is described.

Strains of Staph. aureus isolated from the infants, the mothers and the staff during several weeks of intensive investigations were classified by phage typing.

The findings indicated that, during the latter part of the outbreak at least, the adults were not the source of infection.

There was evidence of wide dissemination of the epidemic strain of Staph. aureus among the healthy infants in the nursery. It is suggested that the main path of infection was from infant to infant.

Methods of controlling established outbreaks are discussed.