1. The present inquiry was designed to provide information on the relative frequency of infection in non-pulmonary tuberculosis with the human and bovine type of tubercle bacillus throughout the whole of England. A total of 149 pathologists at 120 collecting centres and 32 bacteriologists at 27 typing centres took part in the scheme. Two questionnaires relating to each patient were used, one to be filled in by the laboratory workers and one by the Tuberculosis Officer or other responsible official.

1. Tubercle bacilli were isolated and typed from 112 patients in Wales. of these strains, 19 or 17·0 % belonged to the bovine and 93 or 83 % to the human type (Table 16).

1. The reaction horse serum and a pool of rabbit antihorse serum exhibiting four α procedure optima has been investigated with a view to analysing the antigens involved in the production of the multiple zones.

2. The following conclusions have been reached regarding the antigenic constitution of horse serum, a horse serum-albumin preparation and a horse serum-globulin preparation: Horse serum consists of at least five antigens. The horse serum-albumin preparation contains three antigens, two of which are probably impurities, one of these being a globulin. The horse serum-globulin preparation consists of three antigens and evidence was obtained of a fourth. Electrophoretic analysis of these protein preparations gave concordant result.

3. Multiple zones of rapid particulation in the precipitation reaction are due to the independent activity of multiple antigens and their homologous antibodies.

4. The absorption of precipitin from a mixture of antibodies by a mixture of antigens at a single α procedure optimum is both a useful and a practicable procedures.

5. Attention is drawn to the fact that the method of antigenic analysis used in the present series of experiments, involving the correlation of α; procedure optima occurring in the parallel titrations of a single antiserum against a mixed antigen and equivalent concentrations of physically or chemically prepared fractions of it supplemented by absorption of precipitins at individual and multiple α precedure optima and retitration of the absorbed sera, could be applied to the identification and nomenclature of proteins occurring in natural mixtures, and also to the quantitative and qualitative appraisal of the purity of proteins prepared by physical or chemical means. The method does not rely on the preparation of highly purified protein samples containing a single antigen.

The usefulness of the complement-fixation test in differential diagnosis between vesicular stomatitis and foot-and-mouth disease has been demonstrated on two ‘field’ specimens of virus from Mexico. Examples are given of the practical applications of the other methods for this differential diagnosis.

Several species of Leptospira have been studied by means of the electron microscope. Their morphology is described. The Leptospira consists in a long homogeneous cylinder of protoplasm, enveloped in a very thin anistic membrane and wrapped around a slender axistyle. Vibratile structures and granules generally are lacking.

The appearance of Leptospiras differs according to different methods of fixation used and according to different physical or chemical treatments to which they are subjected.

It has been shown that the L-form of Streptobacillus moniliformis is filerable through gradocol membranes which retain the bacillary A-form completely. From the filtration analysis carried out as described it would appear that the particle size of the L-form of Strep. monilifprmis ranges with the larger viruses while the bacillary A-form ranges with Bact. prodigiosum.

The importance of the haemagglutination-inhibition test does not need to be stressed. It is a fact that the inhibition titre of a single serum has no constant value, but may vary in repeated estimations. This may be due to the use of different virus or erythrocyte suspensions or to differences in environmental circumstances, such as temperature. Duplicate tests carried out at the same time and with the same materials yield identical results. This makes it necessary to compare a serum obtained during convalescence from the same case. The ratio between the two titres shows whether an influenza infection has taken place or not. Although it is commonly accepted that a titre rising by two twofold dilutions (a fourfold rise) is significant, some workers will accept even a twofold rise (Sartwill & Long, 1948; Rasmussen, Stoles & Smadel, 1948). Such observations have been made on pairs of sera taken from the same indicidual with not more than a 5-week interval between them.

Change of flagellar antigenic phase in the Salmonellas is considered as resulting from the mutation and back mutation.

A rapid method of determining the phase of numerous colonies of Salmonella typhi-murium is described; melted sloppy agar containing antibody for one phase is layered on tplates on which colonies have grown. On brief incubation, colonies of the agglutinated phase produce narrow dense sharp edged zones of opacity, while colonies of the other phase wide diffuse zones of swarming organisms.

A theoretical analysis shows that if the growth rates of the phases are equal the proportion of cells of ‘mutant’ phase in a culture initially all in one phase and maintained in continuous logarithmic growth will (at first) increase linearly with the number of generations at a rate proportional to the mutation rate. In one strain of Salm, typhi-murium experiments showed the rates of growth of the phases to be equal; the proportion of cells of mutant phase in cultures of this strain during long periods of continuous growth has been measured; linear rates of increase were found, and the mutation rates are calculated.

The variance in proportion of cells of mutant phase in replicate cultures has been measured; the findings are correlated with theoretical considerations.

Certain anomalous decrease in proportion of cells of mutant phase during prolonged growth are described, and a possible explanation is proposed.

Eight further strains have been investigated by the same methods; in the nine strains, the rates of mutation from group to specific phase range from 10-4 to 4.7 X 10-3per bacterial generation cycle, and the rates of the reverse mutation from 10-5 to 8.6 X 10-4. In all the strains, including two of variety binns, the rate of mutation from group to specific is higher than the rate of the reverse change; it is shown theoretically that such strains will tend towards an equilibrium composition in which the specific phase will predominate; in one rapidly mutating strain such an equilibrium has been demonstrated.

In a limited experiment, alteration of medium and of temperature of incubation caused to detectable alteration of rate of mutation per bacterial generation.

Stable O mutants, and poorly flagellated mutants which back-mutate to the fully motile form, are described.

The experimental findings are compared with reports in the literature on the phase of Salm. typhi murium as isolated. The behavior of strains of variety binns is discussed, and it is suggested that this description should not now be applied to strains in which a specific phase can be demonstrated. The biological funtion of mutablility of phase is discussed.

1. None of forty-eight strans of Brucella abortus, ten of Br. melitensis and seven or Br.suis were shown to be lysogenic.

2. It was not possible to ‘adapt’ bacteriophages that were active upon other species of bacteria to lyse brucellas.

3. Thirty samples of faeces, mainly from cows, four sewage samples, twelve specimens of uterine fluid from cows that had aborted, and twenty samples of bulk milk failed to yield bacteriophages active upon brucellas.

Floor dust has been collected for bacteriological examination by three methods: (1) with a miniature vacuum cleaner in which the ‘bag’ consists of a paper Soxhlet extraction thimable, (2)by sweeping, and (3)by blowing the dust on to the surface of a culture plate. The dust on to the surface of a culture plate. the dust from on to the first two methods was shaken with broth and an aliquot sample plated out on crystal-violet blood ager plates.

Surface inoculation of the plates was found to give somewhat higher counts than the use of pour plates, but otherwise minor variations in the routine were without great effect on the count.

Analysis of the results obtained in examining a number of specimerns from schoolrooms and day nurseries showed that, though the counts of streptococci in successive samples from one dust suspension agreed well, there was wide variation between the counts from duplicate samples of dust, however collected; the frequency distribution of the counts in rooms was of the log-normal type. It is clear that in routine work, all the dust collected from the whole floor of a room should be examined, in order to give the most reliable result.

Of 185 specimens in which four colonies of haemolyt streptococci were grouped, 67% had all four strains of group A. Ofniety-four samples in which four group A strains were typed, 55 % had all four strains of the same type; more than one type was found in 20 %.

1. Sodium fluoracetate (1080) has been tested in the field as a poison for Rattus norvegicus and R. rattus.

2. Direct poisoning (without Prebaiting) was used in thirteen tests on R. norvegicus. In eight of these tests censuses showed kills of at least 89% in three tests the poison failed, and in two the results were equivocal.

3. Of three similar tests against R. rattus two were successful and one was a failure.

4. Six tests of 1080 after prebaiting gave five successes (including one against R. rattus), and one in which the estimated kill was about 82%.

5. In five out of six tests populations of R. norvegicus which had survived baiting with 1080 showed shyness (refusal) of the poison when it was given in a new bait base.

6. The LD 50 of 1080 for a strain of white rats was found to be 3·8 mg./kg. (approx. range 2·8–5·2).

7. A number of wild brids and some domestic animals were accidentally killed during the tests despite stringent precautions taken in laying the bait and in warning occupiers.

8. It is concluded that: (a) although 1080 is probably more effective in direct poisoning than other poisons used in the past, it does not give as consistent results as the standard poisons do after prebaiting; (b) 1080 is too dangerous for general use.

1. A preparation containing 0·7% scilliroside (the glucoside of red squill) had been tested as a poison for Rattus norvegicus and R. rattus.

2. The preparation has been found to be effective in the field against norvegicus but not against rattus.

3. Assayed against a strain of white rats, the preparation had an LD 50 for males of about 25mg./kg., and for feamales of about 5 mg./kg.

4. The LD 50 for adult Rhode Island Red fowls was greater than 400 mg. /kg. Pigs, dogs and cats were treated with doses up to 16mg./kg. without fatal results.

5. Silmurine was unpalatable to pigs, dose and cates, but fowls readily consumed a mash containing 1% Slimurine.

1.The results are reported of a study cases of pneumonia, of upper respiratory indection and of family contacts of cases of pneumoia for evidence of influenza-virus infection between October 1947 and April 1949.

2. During an inter-epidemic period in relation to influenza, two sporadic cases of influenza-virus A infection were detected, one in a case of pneumo-coccal pneumonia and the other in a family contact of a case of pneumonia. These were the only instances of virus infection detected amoung 158 individuals including seventy-eight cases of pneumonia.

3. The epidemic of influenza from February to April 1949 was associated with an increase in number of notified cases of pneumonia, particularly in those over 45 years of age compared with the notifications in 1948. Deaths from pneumonia also increased, particularly in those of 65years or over.

4. During the period of influenza prevalence, direct tests of specimens in eggs and serological tests gave positive evidence of influenza prevalence, direct tests of specimens in eggs and serological tests gave positve evidence of influenza virus A infection in many instances. Twenty-six of forty-one cases of upper respiratory infection between February and April 1949 were positive for influenza A and one was a case of influenza B.

5. Eifgteen of fifty-five cases of pneumococcal and staphyococcal pneumoniaccal and staphylococcal pneumonia, eight of fifteen cases of bronchitis, one of two cases of bronchiectasis and four of six cases of congestive heart failure gave serological or cultural evidence of influenza virus A infection during the period of February to April 1949.

6. The mechanism of influenza-virus infection in relation to bacterial infection of the lower respiratory tract is discussed.

‘The Association of certain types (alpha; and β) of Bact. coli with infantile gastro-enteritis’

By J. Smith

‘The Association of certain types (α and β) of Bact. coli with infantile gastro-enteritis’ By J. Smith p. 222, column 1, five lines from the bottom of the page, should read: ‘that the α type should be given the antigenic formula 0 111 B4 and the β type 0 55 B5, since Dr Kauffmann is now satisfied that what was provisionally called 0 112 should now be termed 0 55.’