A study of the occurrence of the common cold in a Wiltshire village during the years 1948 and 1949 showed that, in this community, school children experienced about three times as many colds as adults living in households without schoolchildren, and that the presence of schoolchildren in. the household approximately doubled the numbers of colds experienced by both adults and infants under 5 years of age.

A consistent picture of the state of a bacteria-carrying particle in a bactericidal atmosphere is given. The particle is referred to an ideal ternary system where two of the components are volatile and in equilibrium with their respective vapours. The ideal phase diagrams for systems with one independent variable are given, and the large deviations from the ideal of an actual system are shown from calculations using published data on salivary particle masses in the presence of bactericide vapour at various relative humidities.

When Trichomonas vaginalis in culture medium was exposed in three successive experiments to temperatures fluctuating between +7·2 and +13·0°C., between +10·5 and +15·5° C. and between +5·9 and +7·0° C., two strains survived for 3 days but no longer. One other strain used in these experiments lived for 1 day only, and two other strains did not survive for a single day.

The preparation of purified antigen from canine hepatitis virus sources is described. This includes the manufacture of crude antigenie suspensions and their subsequent treatment to remove non-specific interfering substances.

The solubility of the antigenie substance in various solvents has been studied and its stability is briefly discussed.

The complement-fixation and precipitin tests are described in detail as they have been used for the virus studies.

Various virus-rich body tissues and fluids have been serologically tested, and the identity of antigens prepared from them as well as the antigenie similarity of the various strains of canine hepatitis virus have been established.

The Florida cotton rat, Sigmodon hispidus, has become established as a laboratory animal largely because it is the best known host of the filariid worm, Litomosoides carinii, which is used in routine screening tests for filariacides.

Cotton rats are unsuitable for infecting when very small, and as the filariae take several months to develop enough for the purpose of the test, most of the cotton rats are fully grown at the time of testing. Their weight range is 125–225 g., average about 170 g.

1. The results of feeding albino rats on diets containing 100, 75, 50, 20 and 10 parts per million of the insecticide p-nitrophenyl diethyl thiophosphate (E. 605, Parathion) are described. The feeding of 50, 20 and 10 p.p.m. was continued for a year.

2. At 100 and 75 p.p.m. most of the rats died in the first few weeks. At 50 p.p.m. a few deaths resulted from poisoning, and symptoms were seen on and off throughout the year. At 20 and at 10 p.p.m. no evidence of poisoning was found.

3. Histological examination of animals dying with symptoms showed the lesions of the exocrine glands and the hypoplasia of spleen and thymus that have been reported in acute poisoning by E.605. No other lesions attributable to chronic poisoning were found.

4. Breeding experiments were done with animals from all groups. The second generation of rats fed at 10 p.p.m. produced many dead in their litters. No explanation has been found for this observation.

(1) A collection of S. typhi-murium strains, isolated during 11 months, in or near Manchester, was examined for the presence of symbiotic bacteriophage. In all, 177 strains derived from eighty-three incidents were investigated.

2. The different phages, or combinations of phage, allowed these strains to be divided into eleven varieties. Three hitherto undescribed types of phage were discovered.

3. With two minor exceptions, all groups of strains isolated from associated cases of infection carried the same type of phage, so that the ‘typing’ was in agreement with epidemiological expectations. In the two exceptions, the relationship of the cases was not intimate, and infection from different sources was an obvious possibility.

4. It is concluded that this is a reliable method of typing. It is probably applicable to other groups of bacteria. Its value would be enhanced by the discovery of a simpler method than filtration for sterilizing the lysato without damaging the phage.

In many hospital wards it is usual to have a certain proportion of the beds separately accommodated in single-bed rooms. Current practice shows a great variety not only in the availability of separate accommodation but also in the use made of such a facility. A clear understanding of both the demand and the way in which it can be met is of great importance in the theory and practice of ward design. This problem has been discussed in a recent paper by J. W. D. Goodall (1951), who, using purely medical criteria for the need for separate accommodation, considered that present practice was on the whole largely inadequate. He found it convenient to divide patients into two groups. First, those who have to be kept under close observation, such as dying cases, infants under 2 years, cases of posttraumatic psychosis, patients requiring special treatment, and so on. These are called type A patients, and their beds must be situated for easy observation and attention. Secondly, there are those who need to be separated but who do not require constant nursing supervision, such as patients who are liable to infect others or who are peculiarly susceptible to infection, burns cases and physically unpleasant patients, etc. These are of type B and need not be placed in such immediately accessible parts of the ward. Goodall obtained data from many different hospital wards showing the day-to-day demand for single rooms over, in most cases, at least a month.

1. Type F1 will appear in old Dorset egg cultures of Type F2 after storage for months or years at room temperature in the dark.

2. It is probable that a similar change is responsible for the appearance of Types F1 and F2 in the same carrier and outbreak of typhoid fever.

3. The two types are stable when growing logarithmically in the pure state.

4. There is also evidence that the two types are stable under ordinary field conditions.

5. Logarithmic growth of F1 in the presence of F2 results in the disappearance of F1.

6. This change is caused by a phago carried by F2, which converts F1 into F2.

7. The significance of these observations is discussed. It is suggested that the two types retain their status in the typing scheme.

It is suggested that routine tests for infectious mononucloosis in a large number of apparently unrelated syndromes would disclose a frequent common aetiology and perhaps modify the present conception of the course of the disease.

A technique is suggested for a simple test involving tho demonstration of ox cell haemolysins which would make the testing of large numbers of sera practicable.

The results in sixty cases of infectious mononucleosis and 200 controls are evaluated. The test does not reduce significantly the proportion of serologically negative cases but may confirm the diagnosis before the characteristic sheep cell agglutinins are demonstrable.

The test is as sensitive and as specific as other serological tests for infectious mononucleosis and is very much easier to perform.

The main clinical and pathological features of the naturally occurring canine virus hepatitis were reproduced in dogs, using four strains of virus from different parts of the world and by various routes of inoculation. Young puppies seemed to be most susceptible. A kitten was also infected. An unusual type of kerato-conjunctivitis occurred after both intraocular and intraperitoneal injection.

Specific antigen was detected in the blood for short periods at irregular intervals during the acute stages of the illness and up to 6 months after complete clinical recovery.

Specific antibodies were detected in the blood of recovered animals 3 to 10 weeks after the inoculation and 2–6 weeks after the onset of clinical illness.

The four strains of virus were similar in their serological and immunological characters.

Evidence is presented that virus can persist for some months in recovered animals.

Virus was demonstrated in lice collected from affected dogs.

The importance of clinically inapparent infections is stressed.

Cylinder-model vacuum cleaners cause no bacterial contamination of the air, whereas even on oiled floors domestic brooms caused statistically significant contamination of the air when compared with a vacuum cleaner.

The Hoover model 402 was the only machine tested whose bag is never removed, a theoretical as well as a practical advantage. Domestic brooms can destroy an otherwise efficient barrier nursing system and should bo avoided in hospital wards.