We know, since the time of Pasteur, that repeated passage of rabies street virus from rabbit to rabbit after intracerebral inoculation, leads to a modification of its effect and the appearance of mutative characters. This takes place at a variable period of time depending upon the strain employed. The irreversibility and the permanence of these characters has led to the name of “fixed virus” once the street virus has become adapted for the rabbit.

1. The presumptive coliform test was carried out by each of three workers, at each of four dilutions, on seventeen sets of five tubes for each of seven samples of 18-hour-old afternoon milk, held overnight in the ice chest.

2. With the exception of three slightly anomalous results, the data are consistent with the hypothesis that the chance of a tube remaining sterile is constant for all tubes inoculated from the same sample of milk at any one dilution.

3. The assumption of a Poisson distribution of organisms in parallel tubes is accurate enough, with these data, to give a good idea of the order of magnitude of the number of bacteria per ml.

4. There is, however, a tendency, more marked in our data in autumn than in spring, for the estimated count to rise at the higher dilutions. This may plausibly be attributed to the breaking up of clumps.

In the experiments recorded the various antigens prepared from type I pneumococci failed to produce effective resistance in mice to heterologous types or to produce demonstrable antibodies against these types in mice or rabbits.

This investigation was initiated when twelve miners who were working in a certain part of the Mill Close Lead Mine complained of smarting of the eyes associated with marked congestion of the conjunctivae. They also suffered from a stinging sensation in the nose and throat. The particular area in which they were working differed from other parts of the mine in that there was a strong smell of sulphuretted hydrogen present. After recovery, and when the ventilation had been improved, the men were able to continue working in that area without experiencing further discomfort. The interesting part of the investigation was tracing the origin of the sulphuretted hydrogen. The odour proceeded from collections of mine water which the miners very appropriately called “stink water”. In this there was a deposit of sulphur mixed with black sludge which also smelt strongly of H2S. The sludge consisted of slightly gelatinous black masses mixed with a whitish felt work of a filamentous organism. On microscopical examination the filaments were seen to contain sulphur globules, and often to arise from a mass of black material. This black material consisted of sulphur and inorganic salts in a slimy matrix, the black colour being due to the presence of ferrous sulphide. On further examination these masses were found to be teeming with other bacteria, Gram-negative bacilli and spirilla, both of which were motile, the spirilla being actively so.

1. Five hundred samples of sera sent for the Wassermann test were tested for the presence of H and O agglutinins for Bact. typhosum, Bact. paratyphosum A and Bact. paratyphosum B. Histories were obtained of nearly all those persons whose sera gave H agglutination at dilutions of 1:40 or higher, or O agglutination at 1:80 or higher. It was found that at least 20 people in this series had been inoculated or had suffered from enteric fever. The remaining 480 were considered to be normal. This assumption is likely to be correct in this community where typhoid is the only enteric fever which occurs, and that rarely, and where inoculation is not commonly practised.

2. The results are tabulated so as to show all the combinations of agglutinins which occurred at serum dilutions from 1:20 to 1:1280. Out of sixty-three possible combinations of agglutinins twenty-three were found to occur.

3. The interpretation of the results for single agglutinins and for certain combinations of agglutinins is discussed, and also the application of these results to the diagnosis of typhoid fever in this community and enteric fever elsewhere.

4. A comparison of the local “level” of normal agglutinins with that of other communities is made, and the origin of normal and co-agglutinins discussed.

The transitory leucopenia in the peripheral blood of rabbits following injection of B. typhosus toxic substances is due to the temporary accumulation of neutrophils in the reticulo-endothelial organs. We deduce from this that the phenomenon of leucopenia in the typhoid fever of man is due to the constant liberation of B. typhosus toxic substances in the circulation during the course of the disease.

Chronic irritation is a recognized factor in the causation of malignant epithelial growths and it would not, a priori, be surprising if an association were found to exist between pneumokoniosis and pulmonary cancer. With the notable and somewhat questionable exceptions of the observations upon Schneeberg and Joachimstal miners there has, however, been little to support this view. Nevertheless certain observations of ours (Dible, 1934) have urged us to examine the relationship of silicosis to malignancy in a more specific and comprehensive fashion than has hitherto been achieved. This paper records the results of our investigations, which it is thought may bear upon the aetiology of the condition.

In a few instances outbreaks of food poisoning have been traced with a high degree of probability to rodents (Savage & White, 1925; Salthe & Krumwiede, 1924; Jones & Wright, 1936), but in the main the idea that such outbreaks may be due to contamination of food with the excreta of rats and mice is based on the fact that organisms of the Salmonella group have frequently been found in the faeces or organs of these animals. Savage & Read (1913–14) made cultures from the spleen, liver, heart blood and intestinal contents of forty-one rats after enrichment in liquid media and isolated five strains of Bacterium enteritidis (Gaertner). Savage (1918) obtained four strains of what he regarded as “para-Gaertner” which failed to ferment dulcitol and one strain of Gaertner's bacillus from forty-eight rats by direct inoculation from the spleen and heart blood on to MacConkey's medium. Savage & White (1922) from the spleen, liver, heart blood and intestinal contents of ninety-six rats recovered six strains of Gaertner's bacillus. Kerrin (1928) isolated eleven strains of Bact. enteritidis (Gaertner) from 100 rats. His observations were made on the liver and spleen with preliminary enrichment in brilliant green peptone water and subsequent plating on MacConkey's medium. All these British observations agreed in indicating that Gaertner's bacillus was not uncommonly found in wild rats, but in a much more extended series reported from America by Meyer & Matsumura (1927) twenty-eight strains of Bact. enteritidis (Gaertner) and thirty of Bact. typhi murium (Bact. aertrycke) were isolated from 775 rats. These workers inoculated large portions of liver, spleen and colon into broth containing brilliant green and gentian violet and subcultured on brilliant green eosin agar. Verder (1927), who examined 114 rats in another part of America, records the isolation of five strains of Gaertner's bacillus and one of Bact. aertrycke.

1. Ten pleuropneumonia-like strains isolated from various sources have been selected and studied with a view to discovering reliable criteria for differentiation. Three of them were isolated from the symbiotic association known in the literature as Streptobacillus moniliformis, six from lung lesions of rats and one from a swollen submaxillary gland of a rat. For comparison with these, six other strains, viz. three pleuropneumonia, one agalactia and two of Shoetensack's strains from lungs of dogs stated by him to be suffering from distemper and named by him Asterococcus canis type I and A. canis type II have been included in the inquiry.

2. Classification of the sixteen strains has been achieved by a comparative study of type of growth on liquid and solid media, morphology, pathogenicity and serological affinities. Table VII displays these differences.

3. The serological examination was of special importance for the whole problem of classification. For this purpose an agglutination test was devised which clearly revealed that the sixteen strains belonged to seven different serological types. As the strains of the same antigenic structure showed similar growth types in liquid and solid media and similar morphological appearances, seven species of pleuropneumonia-like organisms were set up:

(a) The L1 organism represents the first species. Three of the strains of this type were separated from Streptobacillus moniliformis cultures. The fourth culture of the same type was found in the lung of a rat, thus proving that this organism may occur independently as well as in symbiotic association.

New evidence of the symbiotic nature of the Str. moniliformis (an association of a streptobacillus with an L1) was given by the agglutination test, in so far as all sera prepared by immunization with Str. moniliformis cultures agglutinated to a fairly high titre the four different L1 strains.

(b) The L3 organism represents the second distinct type species. The five strains belonging to it originate from lung lesions of rats, viz. four from tame laboratory rats and one from a wild rat. This demonstrates that tame and wild rats contain the same variety of pleuropneumonia-like organism in the associated lung lesion. It is believed that 138 pleuropneumonia-like cultures isolated from lung lesions of rats by the writer belong to the same L3 species though only five of them have been studied here in detail.

(c) The L4 organism only once isolated from the enlarged submaxillary gland of a rat also suffering from lung lesions was proved to be definitely different from the L1 and L3 organisms by serological and other tests and represents therefore a third new type species.

(d) Furthermore the organisms of pleuropneumonia, agalactia, Asterococcus canis I and A. canis II would appear to be independent species of the same family.

4. Experiments on pathogenicity which are still in progress show so far that the L3 organism is pathogenic for mice. The L1 organism would appear to be devoid of pathogenicity when tested by similar methods.

5. The capacity of pleuropneumonia-like strains for forming associations with bacteria has been tested experimentally, and in a few cases success has been achieved. These associations with B. tetani and B. tetanomorphus, unlike that of L1 and the streptobacillus in the Str. moniliformis combination, though stable, are not such as to preclude the isolation in pure culture of the two anaerobic bacilli.

6. It is likely that the group of pleuropneumonia-like organisms is widely spread in nature. Search for such strains and thorough investigation of their properties would seem to be of prime importance in view of the minute size of the units which can give rise to growth and the light that might be shed by their study on the biological nature of the filterable viruses.

No case of transformation (in vivo) of the “xylose-positive” typhoid bacillus to the “xylose-negative”, or vice versa, has been observed in any of the material dealt with at the State Serum Institute, Copenhagen.

On the other hand, the types of paratyphoid B bacilli that can be established on the basis of their relation to rhamnose and inositol did not prove to be absolutely constant; actual or apparent transformation of one type to the other having been observed in several cases.

In this connexion the suggestion is made that Bitter's rhamnose reaction be omitted; the distinction between types R1 and R2 would thus disappear.

Patients with symptoms of diseases of the liver and biliary system and also chronic carriers were represented in greater numbers for type R3I1 than for type R2I1, but it is doubtful whether this observation can be taken as a general one. Apart from this, the behaviour of these two types was very uniform as to the clinical course of the infections they produced. The cases of infection with the rarer types, also, did not seem to vary clinically from those with the more frequent types. On the other hand, the difference between the clinical course of paratyphoid B and the infection with Salmonella typhi murium was very marked.

A new Salmonella type, S. kentucky, is described. It was isolated from the intestinal tract of a chick affected with coccidiosis and ulcerative enteritis. The organism possesses two hitherto undescribed antigens, one somatic, the other flagellar. It exhibits alpha-beta phase variation and the alpha phase is identical with the specific phase of S. typhi-murium. The antigenic formula of S. kentucky is VIII XX: i-z6:-.

1. Group variants devoid of type antigen, described in the previous section, provide material for ascertaining the various components of the antigen in the mannitol-fermenting dysentery bacilli.

2. Flexner Y, as defined by Andrewes and Inman, is not a valid type. The strains which are regarded as being of this type, such as Y Hiss and Russell and Y Lentz, are old strains which have lost their type antigen and possess only group antigen. The reason why many newly isolated strains are identified as Y is because the antiserums used for their recognition contain more group than type agglutinin.

3. The four Flexner types V, W, X, and Z, each possess a distinctive type antigen and share a complex group antigen. They do not, as suggested by Andrewes and Inman, possess minor quantities of each other's type antigen.

4. 103, P 119, and the 88-Newcastle-Manchester series have also distinctive type antigens, and share the same group antigen with V, W, X, and Z.

5. It is considered that the existing Flexner group should be extended to include all organisms which have a type-specific antigen and share this common group antigen. The three types in (4) should therefore be placed in the group and named accordingly.

6. Six types which have the biochemical reactions of the Flexner group, and which have individual type antigens but no Flexner group antigen, are provisionally placed in a separate loose group.

1. Material taken from a ferret sick of a disease epidemic among breeders' stocks in 1935 was shown to produce a similar disease when inoculated into normal ferrets.

2. The behaviour of the experimental disease and its pathology indicated that it was a form of distemper, antigenically related to dog distemper, but differing in minor points from the description of canine distemper in the ferret given by Dunkin & Laidlaw.

3. Associated with the disease was a strain of Brucella bronchiseptica which may possibly have been responsible for the high incidence of bronchopneumonia observed.

1. A new technique is described for recovering applied organisms from the skin and other surfaces.

2. Experiments are analysed, in which staphylococci and streptococci are recovered by this technique from various areas of the skin and from glass and rubber.

3. It is concluded that the surfaces examined can be arranged in a definite order of decreasing disinfectant power.

4. The peculiar disinfectant power of rubber is considered.

5. The deterioration in surface viability of streptococci still surviving in saline suspension is described.

6. The experimental results are discussed in the light of previous investigations.

My grateful thanks are due to Professor J. B. Duguid, Department of Pathology and Bacteriology, Welsh National School of Medicine, Cardiff, for his patient counsel and criticism, and to Mr J. P. Napper, Technical Assistant for his skill in making apparatus and his help in the experimental work.

1. The more recent literature on the experimental methods employed in variola or alastrim-vaccinia variation is reviewed and briefly discussed.

2. An account is given of attempts to produce a vaccinia variant from variola of the virulent type and a successful result, by employing the method of intratesticular passage, has been described.

3. The reasons for accepting this as a genuine variation and not a vaccinial contamination are discussed.

4. An attempt has been made to analyse some possible factors underlying the discrepancies in the literature, and a plea is made for more co-operation in future work on the subject.

1. The bacteriological problems involved in the production of meat and fish pastes in sealed glass jars have been studied.

2. Data are presented showing the normal flora of the raw materials used. Particular attention is drawn to the anaerobic species present in seasoning materials.

3. Bacterial contamination due to manufacturing operations is discussed.

4. The requirements of a satisfactory heat treatment are outlined, together with experimental methods of study used to overcome possible causes of failure.

5. Bacteriological examinations of 14,365 samples of paste showed that 88% were sterile: the flora of the remainder was examined.

6. Experimental evidence is presented to show that certain anaerobic spore-forming bacilli are the main possible cause of spoilage, and the significance of aerobic spore-forming bacilli has been established. An extremely heat-resistant anaerobe was isolated.

7. Routine bacteriological control of the finished products is suggested.

8. A simple, inexpensive, and rapid method of detecting anaerobic species has been devised, which can also be applied to other foodstuffs. Data are presented from the examination of a further 6110 samples using this method.

1. A bacteriological examination was made of 1108 samples of water submitted to the laboratory for routine analysis. Of these, 550 contained coliform bacilli and were examined by two different methods. The first method, referred to as method I and officially recommended by the Ministry of Health, involves enrichment in MacConkey broth at 37°C., followed by plating and subsequent identification of selected colonies. The second method, described by G. S. Wilson and his colleagues in their report on milk and referred to as method IV, consists in subculturing every positive 37°C. MacConkey tube into MacConkey broth at 44°C. for Bact. coli I and into Koser's citrate at 37°C. for organisms of the iritermediate-aerogrenes-cloacae group (I.A.C.). In both methods the absolute numbers of coliform bacilli and of the different types are calculated from probability tables.

2. From every fermented tube of MacConkey broth at 37°C. that was plated coliform organisms were isolated. In not a single instance was a false positive, due to non-coliform bacilli, encountered. This merely confirms the general experience in this country of the high degree of specificity of MacConkey broth for members of the conform group. Altogether 2840 strains were isolated by method I and classified according to the scheme given in Table I (p. 310).

3. In the 550 samples Bact. coli I was demonstrated 417 times by method I and 446 times by method IV. The corresponding numbers for I.A.C. were 213 and 449. Method IV therefore proved rather more delicate for the detection of Bact. coli I, and very much more delicate for the detection of I.A.C.

4. Evidence is brought to show that the frequent failure of method I to detect I.A.C. is due partly to a dilution effect and partly to the overgrowth of I.A.C. by Bact. coli I. The chances of demonstrating I.A.C. by method I are remarkably small unless these organisms are present alone, or in numbers greater than or approximately equal to those of coli I.

5. The specificity of the 44°C. MacConkey test for Bact. coli I, and for the infrequent Irregular II which closely resembles it, is very high. For instance, among 2840 strains tested, only fifteen produced gas in MacConkey at 44°C. which could not be classified as Bact. coli I or Irregular II. Only six out of a total of 1086 I.A.C. strains reacted positively to this test. Finally not a single strain, other than Bact. coli I, isolated from 100 samples of human faeces was found capable of producing gas in MacConkey broth at 44°C.

6. The specificity of the citrate test for I.A.C. is not so high as that of the 44° C. MacConkey test for Bact. coli I. In eight out of eighty-one samples of water a positive citrate test was given by organisms other than I.A.C. Examination showed that these consisted of Bact. coli I, non-lactose-fermenters, or of irregular types. Since neither Bact. coli I nor the non-lactose-fermenters grew in citrate in pure culture, and since they were found in citrate tubes that had been subcultured from fermented MacConkey broths inoculated with relatively large quantities of polluted water, it seems possible that their growth was due to the carrying over of small amounts of organic matter into the citrate medium.

7. Observations on the association of Bact. coli II, Irregular I and Irregular II with other coliform types render it probable that Bact. coli II is not mainly of faecal origin, that Irregular I is almost certainly of faecal origin, and that Irregular II may be of faecal origin, but that further evidence will be required to establish this definitively.

8. Owing to the fact that Irregular I does not produce gas in MacConkey broth at 44°C., the faecal coli count by method IV is underestimated, and owing to the fact that Irregular II does produce gas at 44°C., the faecal coli count is overestimated. In this series of examinations the faecal coli count was falsely estimated owing to the presence of Irregular I in 0·4% and owing to the presence of Irregular II in 0·5 % of samples. The combined error of 0·9 % is insignificant in relation to the experimental error of the technique as a whole.

9. By the use of method IV it is possible to demonstrate that (a) I.A.C. is nearly as frequently present in polluted water as Bact. coli I, and when the pollution is only slight may exceed it; (b) I.A.C. tends to be the dominant organism in polluted water that has been subjected to chlorination; and (c) I.A.C. is often present in human faeces (61% of 100 samples), and may sometimes constitute the dominant coliform type. In view of these facts it would seem unwise to neglect organisms of the I.A.C. type in the interpretation of water analyses in this country. Their presence is likely to be of most significance in water of a fairly high degree of purity in which, owing to chlorination or other causes, Bact. coli I can no longer be detected.

10. It is therefore concluded that it would be advisable in future to adopt a method of analysis, such as method IV, which affords a more delicate index of the presence of Bact. coli I, and particularly of I.A.C., in water than the method officially recommended at the present time. The fact that method IV is both simpler, quicker, and cheaper than Method I provides an additional recommendation for this change.

1. A technique for studying the behaviour of Salmonella in milk is described.

2. S. typhi, paratyphi B, dublin, cholerae-suis, typhi-murium, enteritidis and bovis-morbificans all multiplied readily even in absolutely fresh raw milk stored at 15°C., and in commercial grades of raw and of heat-treated milk rapid multiplication also occurred.

3. Strains of S. typhi recently isolated from man showed more rapid multiplication in milk than did stock laboratory cultures.

4. These Salmonella all survived at least 2 months when incorporated in various grades of salted and unsalted butter.

Two new Salmonella types are described. S. minnesota was isolated from a turkey. Its antigenic formula is XXI: b ⇋ enx. S. worthington was found both in a chicken and in a turkey. Its antigenic formula is I XIII XXIII: Iw ⇋ z…. Transfers of each type have been deposited in the National Collection of Type Cultures of Great Britain and in the American Type Culture Collection.

Before dealing with this question it may be appropriate to present graphically the mortality of general paresis in Copenhagen in the period of 1866–1935 (see Fig. 1).