The manuscript notes from which the following Account of the Journal of Hygiene has been prepared for the press were left unfinished by Dr Graham-Smith at the time of his death on 30 August 1950. He intended that the Account should be published to mark the fiftieth year of the Journal's existence.

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.

1. The rigidity of agar gel in poured agar plates can be tested by a comparatively simple and easily repeatable method.

2. Commercial agar from different sources varies in the rigidity of gel it produces at a given concentration.

3. The rigidity of gel produced by any agar at a given concentration is affected by processing and by the mode of production of poured plates and to some extent by the diluent used.

4. The appearance of a spurious S-R change in colonies of Salmonella and Shigella on media with an increasing agar content is a measure of the rigidity of the agar gel used and not directly of the agar concentration of the medium.

5. The appearance of this spurious S-R change induced by rigid agar bears no relation to the agglutinability of the organism.

6. Both increased or decreased agglutinability of cultures of Salmonella and Shigella is associated with the appearance of colonies of an apparently rough morphology at a lower level of agar rigidity than that at which spurious S-R change develops in a normally agglutinable culture.

7. Without some standardization of the rigidity of the gel used in agar plates, erroneous conclusions may be drawn regarding the antigenic state of the organisms under test.

8. Samples of agar of differing gel rigidity can be blended to form a product producing a gel of a calculated 12 sec. value.

I am indebted to the Director-General, Army Medical Services, for permission to publish this article.

G. S. Graham-Smith was born on 25 September 1875, the son of a colonel in the Indian Army. He expressed a wish, during his life-time and in his Will, that no obituary notices should be published about him, because so few of those with whom he was intimately associated during the most active period of his working life now remain. It has, nevertheless, seemed proper to submit the following account of him, because many friends and students and some contributors or subscribers to the Journal who knew him only as editor, will wish to see such details of his life and work recorded.

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.

The type strains of Bact. coli, described by Bray (1945), Giles & Sangster (1948), Giles et al. (1949), Taylor et al. (1949), Smith (1949) and Rogers (1951b), because of their very intimate association with epidemic infantile gastro-enteritis, have been used as indicator organisms to show that the method of cross-infection of epidemic gastro-enteritis is very like that of the cross-infection of burns.

It has been shown how a cubicle becomes widely contaminated within 18 hr. and that type strains of Bact. coli will remain viable in dust for at least 27 days. Communal articles used throughout a ward are blamed for the inter-cubicle spread in a divided ward.

The intimate association of the α- and β-types of Bact. coli with outbreaks of gastro-enteritis is demonstrated, and figures are given to show how these outbreaks prolong the patient's stay in hospital and waste valuable hospital space.

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.

Evidence of how epidemics of infantile gastro-enteritis can spread from one hospital to at least three other hospitals has been presented. Three such outbreaks are described, in two of which the α-type of Bact. coli, and in one the β-type of Bact. coli, were associated with the cases of enteritis.

It is suggested that in hospitals which admit infants routine examination of the infants' faeces should be made to identify these types of Bact. coli, and that institutional epidemics of gastro-enteritis should be notified to a central bureau together with the cultural findings, so that the pooled knowledge could be redistributed to paediatric centres.

The aetiological relationship between infantile gastro-enteritis and these type strains of Bact. coli is briefly discussed.

Small enclosed populations of the common brown rat (ten to twenty-six rats), each with access to one ton of sacked wheat for 12–28 weeks, caused a loss in weight of 4·4% of the wheat. 70·4% of the wheat was fouled and had to be cleaned before use. The main monetary loss was due to damage to sacks. Total monetary loss was 18·23% of the original value of the wheat and sacks.

The prevalence of the different types of coli–aerogenes bacteria has been determined in various soils collected from widely separated locations in the United Kingdom and in Denmark. Of the soils examined, 27% contained no coli–aerogenes organisms in 15 g. of soil tested. The number of these organisms in the positive soils was very low; only 11% had confirmed counts greater than 100 organisms/g. and 33% less than 1 organism/g.

The most prevalent organism isolated was Bacterium coli type I, whatever the location or vegetation type of the soil; intermediate type I, Bact. aerogenes type I and Bact. coli type II were the only other organisms of numerical importance. The annual application of large amounts of either farmyard or inorganic manures produces no permanently large population of coli-aerogenes organisms in soils.

Presumptive tests in MacConkey broth were unreliable, since only 6 % of the positive tubes from hill and moorland soils and 28 % from arable soils were confirmed as containing coli-aerogenes bacteria. Such discrepancies are considered to be partly due to coliform bacteria with weak lactose-fermenting properties.

It is considered that there is now sufficient experimental evidence to discredit statements that soil is the natural habitat of Bact. aerogenes or intermediate types of coli-aerogenes organism.

A transformation devised by Mather is applied to give a new scheme for computing the maximum likelihood estimate of a bacterial density from the evidence of a dilution series. Tables are provided to expedite the application of the method; with their aid, the calculations take a from similar to, but much simpler than, those for probit analysis of quantal responses.

Maximum likelihood estimation is compared with the method proposed by Fisher. The latter has the advantage of extreme simplicity, at least for series to which existing tables can be applied, and the loss of information involved in its use may often be compensated by the saving of time in calculation. An experimenter who has fairly reliable prior indications of an approximate value for the density, however, ought to concentrate his attention on dilutions that he believes will contain between 4 and 1/4 organisms per sample; he must not apply Fisher's method to his results, but the maximum likehood estimate will be so much more precise than any estimate from an experimental design using more extreme dilutions as to repay the small additional labour in computation.

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 injection of mice with botulinum spores, freed from all traces of superficial toxin, can cause death but only if a very large number is given. This number was found in the case of a highly toxic strain to be of the order of 20 million spores given intramuscularly. This dose was fatal in the absence of spore germination.

2. In human botulism it is concluded that the spores of Clostridium botulinum persent in spoiled foodstuffs are not of importance compared with the toxin produced by the initial growth of the contaminating organisms.

3. Toxin could be demonstrated in the cytoplasm of botulinum spores when these were disintegreted by mechanical means. This is of theoretical interest as the toxin within the spores is more heat-stable than the extracellular form.

4. A local anaerobic myositis could be produced in mice by the intramuscular injection of spores plus 2·5% CaCl2. The number of viable spores in the LD50 was of the order of 50,000.

5. Calcium chloride solution in the commonly used strength of 2·5% was shown regularly to cause a drop in the number of botulinum spores in a given suspersion of some 40% and a parallel loss of viability of about 60%.

The lysis of Bacterium coli suspensions brought about by glycine shows the following characteristics:

(1) There is a latent period of 2 hr., followed by a rapid lysis reaching a maximum in about 8 hr.

(2) The extent of the lysis is independent of the dilution of the bacterial suspension over a wide range.

(3) The extent of the lysis increases with the glycine concentration up to 10M, but is approaching a limit at this concentration.

(4) The lysis is negligible below pH 5 and above pH 10, and shows a maximum rate in the region of pH 6–5–8–5.

(5) The rate of lysis has a very high temperature coefficient (Q10 of the order of 5).

Actinomyces bovis passes through a complete life cycle. The spore germinates to produce a haploid generation, from which a diploid generation arises by conjugation of two specialized haploid cells. A haploid spore is produced from the diploid generation by reduction division.

The life cycle of Nocardia starts-with the microcyst, which germinates by budding. The bud develops into a long multinucleate filament, which becomes divided into individual cells by the formation of transverse cell walls. Microcysts are formed in the same manner as in the Eubacteria. Multiplication of the cells takes place by simple fission, by complex vegetative reproduction, and by branching. They do not have a prolonged diploid phase like the Actinomyces.

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.

1. Evidence is submitted that an anomalous rabbit cell lysin reported by Minett (1936), α2-toxin and δ-haemolysin are identical. The last name is preferred.

2. Precautions are necessary to avoid interference by δ-haemolysin in titrations of α-toxin and α-antitoxin.

3. The existence of γ-haemolysin is confirmed; its wide distribution and possible confusion with α-toxin are noted. The name γ-toxin is thought more suitable than γ-hameolysin.

4. Multiple standard antisera are desirable for the detection of anomalous toxins. At least one should be of refined globulin.

5. Dilution and manipulation inactivate staphylococcal toxins and their effect needs consideiration in quantitative work. Infusion broth increases the stability of diluted α- and β-toxins.