1. Recovery of a strain of Brucella abortus Bang from a foetus aborted by a cow in Mauritius is reported.

2. Agglutination tests performed on samples of blood from cows of the Government Dairy indicate that contagious abortion of cattle is present in this country; approximately 24% of the animals from the Government Dairy belonged to the latent or past infection group; 18 % to the active infection group and 15% were presumptive bacilli excreters.

3. As aresult of agglutination tests with the blood serum from man Undulant fever due to Br. abortus is suspected to occur in Mauritius.

1. An outbreak of Salmonella derby, involving sixty-eight patients, is described.

2. The organism was isolated from clinical cases, from carriers and also from dust in the wards, from a mouse and from a hand towel used by nurses.

3. The value of tetrathionate broth with subsequent cultivation on ‘SS’ agar as an aid to isolation of Salmonella bacilli was confirmed.

4. Cultural and biochemical characters of Salm. derby were recorded.

5. The antigenic structure of the isolated strains of Salm. derby was demonstrated, showing the presence of factor l and the absence of a minor flagellar antigen.

6. A serological response to Salm. derby infection was shown in patients, their sera containing H antibodies of a titre 1/20 to 1/320, whereas O agglutinins were absent at the time the tests were made.

7. Pathogenicity tests were performed on mice indicating the possibility of infection per os or by intraperitoneal injections. Mice were found to be potential faecal and urinary carriers.

1. Fresh-water fish possess serum agglutinins specific for the bacteria which parasitize their peritoneal and opercular cavities, and also for the bacteria inhabiting the water in which they live.

2. The titre of these agglutinins is low in spring and rises during the summer months, in a manner which corresponds to the summer decrease in infection.

3. Similar agglutinins are found in frogs.

4. These observations provide additional evidence that water bacteria are capable of parasitizing aquatic animals.

1. Vaccinated rabbits develop serum anti-haemagglutinin after infection. The anti-haemagglutinin is not found to any appreciable titre in normal human and animal sera tested. It is present in the globulin fraction of rabbit serum and is stable at 70° C. for 30 min. but destroyed at 80° C. for 30 min.

2. Observations over a period of 6 months of variations in serum antibodies in vaccinated rabbits demonstrate that whereas the agglutinin, precipitin and complement-fixing antibody varied in parallel with each other, the anti-haemagglutinin varied independently and in general remained more or less steady throughout the period.

3. Some experimental observations of the haemagglutinin anti-haemagglutinin reaction are reported. The haemagglutinin inactivated by immune serum can be reactivated by boiling. Haemagglutinin adsorbed on to red cells can be eluted by subsequent addition of immune serum.

4. Failure to obtain complement fixation with the haemagglutinin anti-haemagglutinin system is recorded.

5. Vaccinia haemagglutinin is distinct from the L-S antigen.

6. By absorption test, it has been shown that the anti-haemagglutinin is a distinct antibody related neither to L or S antibodies nor to neutralizing antibody.

7. It is concluded that vaccinia haemagglutinin represents a new and distinct antigen occurring in a relatively large particulate state in vaccinia infected tissues. The possible theoretical implications of such findings are discussed.

The bacteriological examinations of 1616 samples of polluted water from the Melbourne supply revealed that the production of acid and gas in MacConkey or in lactose broth was not always evidence of the presence of a coliform bacillus. There was, however, a marked difference in the number of confirmed samples in the two media. Among 1136 samples incubated in MacConkey broth coliform organisms were isolated by plating in 98·4%, but among 480 samples enriched in lactose broth 10·8% failed to confirm. MacConkey's broth is therefore recommended as the better medium for the presumptive coliform test in Melbourne water.

The technique used in the examination of 1345 samples of water and 73 samples of animal faeces was Wilson's method IV extended by plating from at least one tube giving a positive presumptive reaction at 37° C. to include method I also. In both series of tests coli I appeared to be by far the more numerous type by method I, but when method IV was used the intermediate, aerogenes, cloacae group (abbreviated to I.A.C.) was detected in almost as many samples in water and in 63% of the faeces where the numbers were often very low compared with coli I. Unless I.A.C. was present alone or in large numbers in relation to coli I it was frequently missed by the plating method. Even coli I was more often found by method IV which proved, therefore, to be a more delicate test than method I for both types of organism.

The 44° C. test for coli I proved to be highly specific in Victoria, since few organisms were able to produce acid and gas in MacConkey broth at 44° C. except coli I and organisms which had affinity with coli I rather than I.A.C. This contrasts with results reported from Madras (Raghavachari, 1939) and Singapore (Boizot, 1941) where the test appears to be less specific, but is in agreement with British (Bardsley, 1938; Batty-Smith, 1942) and Argentine (Ferramola, 1940) experience where the 44° C. test has also proved to be of high differential value.

Growth in citrate in method IV was sometimes due to coli I, non-lactose fermenters or Pseudomonas pyocyanea, particularly when lactose broth was the enrichment medium.

Bact. coli II and irregular I were found in heavily and in lightly polluted waters, and were associated rather more often with coli I than with I.A.C. They were seldom found in animal faeces. Irregular II rarely occurred among the organisms cultured, but the evidence suggests that it may be of faecal origin.

The coliform counts on decaying leaves, algae and other vegetable debris found in the sumps and on the screens were very high, and the figures showed a heavy increase after incubation.

Periodic sampling of cow dung left to dry in the open meadow showed that reduction in coliform count was very gradual and largely dependent on the moisture content, and that coli I was still overwhelmingly dominant 3–7 weeks after the samples were voided. Laboratory experiments, in which cow faeces were stored in moist and in dry chambers, gave similar results.

Soil plots low in organic matter were watered with cultures of coli I, intermediate I or aerogenes I and sampled at intervals. All three types tended to die out gradually and there was no question of intermediate I or aerogenes I growing and multiplying under the conditions of the experiment, neither were any profound changes apparent in the biochemical reactions of the three types as a result of prolonged sojourn in soil. Soil which had been heavily contaminated with cow manure 3 years previously still contained large numbers of viable coli I.

A description is given of a simple method of determining the sensitivity of bacteria to sulphonamides by means of impregnated blotting-paper disks applied to nutrient agar prepared from broth freed from sulphonamide antagonists by incubation with lysed horse red blood cells.

With organisms sensitive to the selected sulphonamide, a zone of inhibition of growth will occur, the diameter of which is related to the concentration of the sulphonamide necessary to inhibit growth. Sensitivity to several sulphonamides can be determined simultaneously.

The impregnated disks can be stored without loss of potency.

1. An outbreak of gastro-enteritis in hospital due to Salmonella derby is described.

2. The probable pathways of infection are indicated diagrammatically (Text-fig. 2).

3. Attention is drawn to the importance of dust as an environmental source of infection in gastroenteritis in a closed community.

4. Methods of control including the detection of carriers, the avoidance of contact with anything that goes into an infant's mouth and the protection of exposed food from dust contamination are stressed.

1. A new series of compounds has been found which markedly inhibits the growth of Mycobacterium tuberculosis and M. smegmatis.

2. These substances are strongly haemolytic against human red blood cells.

3. The effectiveness of the antibacterial and haemolytic actions depends upon the length of the alkyl chain.

4. The antibacterial and haemolytic actions are reduced by human serum.

When a number of organisms are exposed in early rapidly multiplying broth cultures to minimally effective bacteriostatic concentrations of a number of antiseptics, almost complete lysis may be demonstrated.

When older cultures are exposed to low concentrations, or young cultures to strong concentrations, lysis does not occur in many cases.

The lytic effect of penicillin is apparently identical with that of the antiseptics tested. The phenomenon appears to depend on the nature of the effect of the antiseptic on metabolic enzymes, autolytic enzymes, or both.

1. The nature of the probit-log survival-time relationship in the disinfection of standard cultures of Bact. coli at 51° C. at pH values ranging from 2·8 to 8·8 has been studied.

2. It is concluded that there is a very close approximation to a bilinear form in all cases, though there was evidence that a continuous curve concave upwards and to the left would provide a better fit.

3. Probit limits, corresponding to the range of percentage mortality within which, having regard to the experimental error involved, an observation might lie, have been worked out. The range covered by these probit limits decreases as the percentage mortality rises.

4. These limits have been used to decide whether a bilinear or a single straight line treatment should be applied to certain sets of data. It is suggested that they would often materially assist in deciding the range over which linearity may be assumed in any given case.

A colony count performed by spreading a known volume of suspension on the surface of a plate possesses certain advantages over other methods, of which the chief is ease of counting.

The distribution of counts of several samples of the same suspension on medium of the same age and batch is as expected on statistical grounds.

Different batches and ages of blood plates may give substantially the same count but this is not true for Leifson's and Wilson & Blair's media.

A diluting fluid, which is satisfactory if blood agar is the plating medium, may not necessarily be so if special media are to be used.

1. An outbreak of typhoid fever in a Royal Air Force camp in the Middle East is discussed.

2. A total of 110 cases occurred of which 105 are analysed. The case-fatality rate was 10%.

3. Of the 105 cases 59% gave a positive blood culture. The percentages of diagnostic isolations from stools and urine were small.

4. Clearance tests of stools and urine showed that 8.4% of patients excreted Salm. typhi during convalescence.

5. Leucocyte counts during the first 2 weeks of the illness showed that only 30% of the patients had a count below 5000 per cu.mm.; 62% of these low figures were encountered in severe cases.

6. Autopsies on seven fatal cases showed considerable variability in the macroscopic appearance of the intestinal lesions.

7. Serological investigation confirmed that higher percentages of cases with low titres of O agglutinin were found in the severe and mild clinical groups, and that most O titres in the moderately severe cases exceeded 1:200.

8. Of the patients 52% showed Vi titres exceeding 1:20 during convalescence.

9. The significance of various findings is discussed.

1. Data obtained by the disinfection at 51° C. of standard cultures of Bact. coli at pH values ranging from 2·8 to 8·8 have been used for the calculation of the concentration exponents of hydrogen and hydroxyl ions. The times taken to reach various degrees of mortality from 50 to 99·99 % have been taken as measures of the activities of the ions.

2. The formula Cn×t = constant proved satisfactory for describing the data for all the mortality levels and at all the pH values tested except pH 2·8, 6·25, 6·4 and 7·0. In these instances the cultures exhibited heightened sensitivity, though the results at all, except pH 2·8, could be included when the 99·.99 % mortality times were used. The exponents increased sharply at pH values below 3·9.

3. The values of the concentration exponents varied similarly under both acid and alkaline conditions, according to the mortality level chosen. The largest value was obtained from the 90 % mortality times, there being a decrease when both higher and lower levels were employed. The changes were greater under acid conditions, when the values ranged from 0·60 to 0·25, compared with 0·60–0·47 for the alkaline reactions.

4. The mean of the pH values for maximal survival at the various mortality levels, derived from the regressions of log mortality time on pH, was ·51, but this was close to a point of greater susceptibility. Experimentally, maximal survival occurred at pH 6·65, which is very near to the neutral point of water at 51° C.

5. It is concluded that within the pH range 6·25–7.0 the hydrogen and hydroxyl ions were relatively inactive, the effects observed being due to other factors possibly including the action of undissociated water molecules.

The authors acknowledge with thanks the receipt of a grant from Messrs I.C.I. (Pharmaceuticals) Ltd. towards the expenses of this investigation.

1. The process of nuclear fusion and reorganization as it occurs in members of the Bacteriaceae is described.

2. The chromosomes behave as pairs at all times, the normal bacillus, of smooth morphology, contains two pairs.

3. The fusion nucleus contains three pairs and is preceded by a corresponding trinucleate bacillus.

4. One division of the chromosomes takes place in the fusion nucleus, and another during the process of redistribution of the chromosomes. The second division is followed by fragmentation, and return to the bacillary condition.

The use of fumigants against insects attacking stored products involves two possible dangers. In the first place workers may be poisoned by inhaling the fumigant either during its use or its manufacture. Secondly the fumigant may be adsorbed onto food-stuffs thereby hazarding the health of consumers.

Our data suggest that there are four different thermolabile antigens in S. dysenteriae (Shiga) appearing in different combinations in the five variants described. These antigens are:

1. The agglutination-inhibiting factor ‘I’, found in variants 1 and 3, which is a typical surface antigen.

2. A precipitinogen, ‘N’, probably identical with the neurotoxin, found in variants 1, 2 and 5.

3. A labile precipitinogen, ‘A’, in the extracts of variants 1 and 2, occurring in the deeper layers of the bacterial cell.

4. An additional precipitinogen, ‘B’, found in extracts of variants 1, 2, 3 and 4. It differs from the other labile antigens as its combining- and immunizing-powers are not destroyed by heating at 100° C. for 2 hr.

Recent research has even further emphasized the physiological dangers to which man is exposed when breathing gases at increased tensions. If he breathes air his activity under water is greatly limited by the problems of supply and compressed air illness. The latter is due to the formation of bubbles of nitrogen in the body on return to normal atmosphere. If he breathes oxygen, then he is in grave danger of oxygen poisoning, with convulsions, even at relatively shallow depths (Donald, 1947). During the recent war, mixtures of nitrogen and oxygen were employed for important work where the diver wished to go to considerable depths while carrying his own gases. These mixtures were varied in composition and rate of supply so that oxygen poisoning was avoided, and immediate rapid surfacing was possible, without compressed air illness occurring. However, this ingenious compromise is limited in its application, for as greater depths are reached, the oxygen has to be greatly reduced to avoid convulsions. The resultant rise in the proportion of nitrogen being breathed causes bubble formation in any but the shortest exposures. It is to be doubted whether the maintenance and meticulous supervision required, when using mixtures, will allow the use of these in the more normal conditions of peace-time. It has become increasingly apparent that the prolonged underwater survival of men requires pressure-withstanding devices in which he can exist at normal physiological tensions, i.e. atmospheric pressure. The rigid diving suit and submersible chambers, such as the bathysphere, are in their infancy; but the submarine, where the same conditions apply, is now a highly successful and developed method of underwater existence and locomotion. The further evolution of these devices, and of the submarine, depends mainly on engineering advances and not upon attempting to extend the comparatively rigid limits imposed by human physiology. The maintenance of a healthy atmosphere within a submarine is again a chemical and engineering problem which is capable of solution and constant improvement.

1. Anti-mallein and anti-typhoid sera produced in various animal species, including man, have been examined for complement-absorbing antibodies using the complements of the pig, horse, cat, man, dog, and guinea-pig, which is possible if use is made of the conglutinating complement-absorption test as well as the haemolytic complement-fixation test.

2. Complement-fixing antibodies which are not demonstrable when some complements are used may be detected when other complements are used; for example, antibodies to mallein in human antisera were only detected when the sera were tested with horse and cat complements.

3. These early results are published at this stage because of the obvious possible application of these methods in laboratory serological diagnosis. Further work is in progress to elucidate the underlying reasons for these observations.

4. The implications of the results are discussed from the practical and theoretical aspects.

Guinea-pigs are usually mated in permanent polygamous groups, one or more males with a large number of females, the young being harvested when ready to wean. This system is economical of labour, and is efficient in allowing of mating at post-partum oestrus and therefore of maximum reproductivity. There are, however, serious disadvantages; it is difficult to keep track of individual performance and difficult therefore to eliminate unproductive sows, the ancestry and exact age of the young are often unknown, and the conditions of rearing young among a crowd of adults are probably not ideal. These considerations suggest that, given high-grade breeding stock, the polygamous system is adequate, and probably inevitable, for the mass production of young for experimental purposes, but that it leaves much to be desired for the production of breeding stock. The obvious solution of this difficulty is to maintain a large polygamous and anonymous colony for mass breeding, and, quite separately, a small closely recorded colony to supply the breeding animals. A goodsow should produce at least 10 young per year in a life of 2 years. A demand of 10,000 animals per year, for experimental work, therefore requires a mass-breeding stock of 1000 sows, an annual replacement of 500 sows and a stock-breeding stock of 100 sows. According to our experience, about 2 hr. daily on the part of a trained technician would be required to maintain close recording of such a pilot stock and of its progeny to puberty (Bruce & Parkes, 1947b).

It has been shown that certain strains of Salmonella grown in nutrient broth containing sulphite and bismuth, develop variants that are incapable of reducing sulphite to sulphides in the media of Wilson & Blair.

The altered strains showed no alterations in their antigenic and biochemical characters.