(1) Reaction changes and production of gas in organic salt media are not sufficiently constant to form a reliable diagnostic criterion for the differentiation of bacterial types.

(2) The enhancement or inhibition of bacterial growth in such media in the majority of cases bears a direct relationship to the utilisation of the salt by the organism. This furnishes a useful differential test for certain organisms when citrates are used, but cannot be applied in the cases of all salts.

(3) The bacterial decomposition of the salts of those organic acids which form insoluble lead salts can be clearly demonstrated by the addition of suitable quantities of a solution of lead acetate to the culture.

(4) By the use of six organic salts, seven different groupings of the common Salmonella types can be obtained, whereas the sugar reactions have, up to the present, yielded only four different groupings.

(5) Regarding other groups of bacteria, the organic salts form an easy means of distinguishing between pathogenic and certain non-pathogenic vibrios, and between certain of the members of the coli-aërogenes group, and also between B. diphtheriae and Hofmann's bacillus, as well as between B. mallei and B. whitmori.

(6) The six organic salts employed in this test are relatively inexpensive, will stand sterilising by autoclave, and can be obtained with certainty in a state of purity much more readily than the rarer “sugars.”

(7) The nature of the decomposition products of citric acid has been fully examined in the case of Bacillus suipestifer; it has been shown that the products are acetic acid, carbon dioxide and succinic acid, and a simple explanation of the mechanism of this reaction is put forward. In the case of fumaric acid a preliminary examination shows that the acid is converted into succinic acid probably by direct reduction. Maleic acid appears to behave in an analogous manner to fumaric acid. Further work on these acids is in progress.

(8) A large number of organic acid salts have been tried, but only the six suggested have given useful results. It appears that simple aliphatic monobasic and dibasic acids, with the exception of formic acid, are not decomposed readily by the bacteria investigated, and this is also true of monohydroxycarboxylic acids. Readiness of decomposition is first shown by the dihydroxydicarboxylic acids (tartaric acids), and appears to be at its best in the hydroxytricarboxylic acid (citric acid).

(9) While organic salt fermentation tests have been found particularly useful in the cases of the bacterial groups dealt with in this paper, they cannot be substituted for the “sugar reactions” in general use.

The two generally recognized divisions of the country are the Delta (Lower Egypt), extending from the Mediterranean littoral to Cairo; and Upper Egypt, the narrow strip of alluvial soil in the Nile Valley from Cairo to Wadi Halfa. The valley of the Nile is a rift valley formed by the subsidence of a narrow belt in the neighbourhood of a line of fracture on the earth's surface; from Cairo to Aswân town its length is 880 kilometres (547 miles), and its width varies from 3 to 21 kilometres (2 to 13 miles). The province of the Faiyûm is a depression which is irrigated from the Nile by the Bahr Yûsef Canal, one of the old natural drainage channels of the valley.

(1) It is impossible to distinguish the lesions of melioidosis from those of glanders by means of inspection with the naked eye or even with the microscope.

(2) The symptoms and course of the two diseases are similar. Melioidosis generally runs a more acute course.

(3) The mallein test was applied in a case of chronic human melioidosis and gave a positive reaction. The mallein was obtained from Java.

(4) The blood of this chronic case agglutinated the Muktesar and Java strains of B. mallei to full titre and the Minett strain to 10 per cent, of this amount. One of these strains (Muktesar) absorbed the agglutinins for the homologous bacillus.

(5) There are very few horses in the Federated Malay States. Melioidosis is primarily a disease of rodents. All attempts to infect horses have been unsuccessful.

(6) Melioidosis broke out spontaneously among the rabbits, guinea-pigs and rats at the Institute for Medical Research in 1913. The animals became infected through eating contaminated food.

(7) Cases of infection in wild rats and in a domestic cat have occurred far away from this laboratory and independently of it.

(8) Rabbits, guinea-pigs and rats have been infected experimentally, by feeding, by subcutaneous inoculation, by scarification and by the application of infective material to the nasal mucosa.

(9) B. whitmori, whose growth in cultures occur in two forms, a commoner corrugated form and a mucoid form which gives origin to the corrugated type.

(10) B. whitmori differs from B. mallei in the following particulars. It is actively motile. It forms a corrugated growth on glycerine agar, a white opaque growth on ordinary agar and a pellicle on the surface of broth. It grows more rapidly than B. mallei, and it liquefies gelatine in a few days.

(11) B. whitmori resembles B. mallei in the following particulars. The morphology of the organisms is similar. Young cultures of the mucoid form are indistinguishable from B. mallei, by inspection. The growth of the mucoid form on potato is similar. The action on milk and carbohydrates differs in degree only. Both organisms produce Strauss's reaction in guinea-pigs.

(12) Five strains of B. mallei were compared with fourteen strains of B. whitmori. The cultures of B. mallei comprised three from the National Collection at the Lister Institute, one from Muktesar and one from Java. The cultures of B. whitmori had been isolated, some from human cases of melioidosis and some from animals which had acquired the disease naturally.

(13) The serological reactions of these organisms, namely agglutination, absorption and complement-fixation tests, showed that the cultures of B. whitmori were a homogeneous group, but the five strains of B. mallei were sharply divided into two sub-groups by their serological reactions. One sub-group includes the Muktesar and Java strains; the other comprises the three strains from the National Collection (Minett, Egypt and A.).

(14) The first sub-group of B. mallei is very closely related to B. whitmori. The serological reactions of the strain from Muktesar are almost identical with those of B. whitmori.

(15) The three strains of B. mallei from the National Collection, which form the second sub-group, are only distantly related to the Muktesar sub group and to B. whitmori.

The fermentation reactions and some ancillary characters of 102 strains of virulent C. diphtheriae, 31 non-virulent strains and 150 diphtheroids have been studied.

With the possible exception of dextrin which proved to be an unsuitable substance for biological tests all the strains of virulent C. diphtheriae examined were found to have constant biochemical reactions, fermenting glucose, maltose and galactose and having no action on cane-sugar, lactose and mannite.

The strains classified as non-virulent C. diphtheriae had the same biochemical characters as the virulent strains and were indistinguishable from them either on morphological or cultural grounds.

The diphtheroids examined showed great diversity in their power of attacking the carbohydrates used, at least eleven biochemical groups being recognised.

By the use of three carbohydrates, glucose, galactose and cane-sugar 90 per cent, of the diphtheroids in this series could be distinguished from C. diphtheriae by their fermentation reactions. In the remaining 10 per cent, a clue as to the nature of the organism is often obtained from the character of the growth on agar.

Among the corynebacteria examined other than C. diphtheriae no constant relationship was found between source, biochemical, morphological and other characters.

Nevertheless in dealing with members of the genus in pure culture, the morphology, character of the growth on agar and fermentation reactions taken together give useful information as to whether the organism under consideration is C. diphtheriae (virulent or non-virulent) or a diphtheroid.

My best thanks are due to Dr Ledingham for much help and advice given throughout the work and to Dr Atkin and Dr Robison for their assistance in dealing with the lactose and dextrin problems respectively.

There are many forms of bacterial disease in which the search for the causal organism is complicated by the fact that it is present, not in pure culture, but associated with the number of other bacteria which may or may not be taking part in the infective process.

IN 1913, Fraenkel and Much1 inoculated monkeys, guinea-pigs, rabbits and dogs intraperitoneally with large quantities of material obtained from two cases of Lymphadenoma, no accompanying tubercular disease being demonstrable. The material was broken down with antiformin, and as a result of the injections, the guinea-pigs died within three months. The authors state that besides finding extensive tubercular disease, there were hard, white nodules, the size of a cherry stone, on the serous coverings of the stomach and mesentery. Also, in addition to genuine tubercular disease of the lymphatic glands, they found giant cells, not of Langhans' type, as well as a stroma rich in fibriles, similar to what is found in Lymphadenoma. The nodules on the serous surfaces showed a picture corresponding to the terminal fibrous stage of a lymphadenomatous focus, with a scarcity of cellular elements.

Every bacteriologist is only too well aware of the many problems presented by the preparation of culture media for the growth of bacteria in vitro.

In the preceding pages, an analysis has been made of the correlation coefficients found between the number of fatal cases from bronchitis, pneumonia and respiratory diseases, or the two summed together, in children under five years of age in London, Glasgow, Edinburgh, Aberdeen and Dundee, and the meteorological factors, mean and mean minimum temperature, mean relative humidity and mean rainfall, for a period of from 40 to 50 years; and between the death-rates from bronchitis, pneumonia and respiratory diseases amongst children at the same period of life in the registration counties of England and Wales in the decennia, 1901–10 and 1891–1900, and their mean annual temperature and mean annual rainfall and it seems warrantable to draw the following conclusions.

1. The meteorological factor, amongst those investigated, that seems to exercise the greatest influence in predisposing to an increased mortality from, and presumably an increased incidence of, bronchitis in children in the cities, is the prevailing temperature. In accordance with the average duration of the disease, the mortality is most intimately related to the mean temperature of the preceding week and is, on the average, as closely related to the temperature of two weeks before as it is to that of the corresponding week. The relationship is inverse, the lower the mean temperature the greater the fatality from bronchitis. As suggested by Dr Leonard Hill, the cold weather probably compels children to remain indoors in stuffy, overheated rooms where infection is intensified and health weakened by heat stagnation, a lowered metabolism and want of sunlight.

2. While there is a suggestion from some of the correlation coefficients found, that pneumonia in children may have some inverse relationship to mean temperature this association is not shown in the monthly or weekly data generally.

3. There is a definite inverse relationship between the mortality from the respiratory diseases, or bronchitis and pneumonia summed together, and the mean temperature; and, as occurs with bronchitis, the relationship to the mean temperature of the preceding week is closer than to that of the corresponding week.

4. The mortalities from bronchitis, pneumonia and respiratory diseases (bronchitis and pneumonia summed together), in children under five years in the registration counties of England and Wales, are inversely associated with the mean annual temperature in the corresponding counties. This association still persists after allowance is made for the proportion of each county which is urban, a proportion which has been taken as a rough index of industrial conditions therein.

5. The mortalities from bronchitis and pneumonia in children in the cities examined and in the registration counties are not influenced in any consistent manner or degree by the amount of rainfall.

6. While the coefficients of correlation between the corrected monthly deaths from bronchitis and respiratory diseases, respectively, and the corresponding mean monthly humidity in Glasgow seem to suggest the existence of a significant direct association between these variables, viz. the moister the atmosphere, the higher the death-rate from bronchitis; such a relationship is not definitely indicated in the coefficients found for the other cities. The magnitude of the coefficients for Glasgow is apparently determined, in some degree, by the periodicity in the mortality figures. It is probable, however, that the periodicity is not wholly responsible for the correlation found as the correlation coefficients between the mean temperature and the deviations in the same monthly data from the five-yearly moving average—the method adopted to eliminate the effect of the periodicity—are not very different from those found by using the actual figures. There would appear to be some evidence for the view that a high relative humidity, when associated with a low temperature, has some influence in predisposing to an increased mortality from the respiratory diseases.

Two cases of fatal melioidosis are described. The first a robust Indian labourer; the second a well-nourished, muscular European.

Case 1. Gradual onset. Irregular fever. Pain in the epigastrium. No physical signs of disease at first, except enlarged spleen; later, there were signs of consolidation at the bases of both lungs. Constipated at first; diarrhoea came on towards the end and the patient collapsed and died at the end of the third week.

At the autopsy; there were small patches of consolidation in the lungs, composed of minute suppurating tubercles. In the liver there were similar aggregations of small suppurating tubercles and two circumscribed abscesses. The gall-bladder was thickened. The spleen was enlarged and contained septic infarcts and abscesses. In the caecum there were small superficial ulcers. B. whitmori was cultivated from the lungs, spleen, liver and gall-bladder.

Animals were inoculated as follows: A guinea-pig, inoculated in the anterior nares with pus from the liver, died nine days later with caseous inflammation of the nasal passages and a caseous inguinal gland from which B. whitmori was recovered. A guinea-pig, inoculated subcutaneously with pus from the liver, died on the twenty-fifth day with abscesses in the lymphatic glands from which B. whitmori was cultivated. A guinea-pig, inoculated subcutaneously with a culture of the organism, died within sixteen hours from septicaemia. B. whitmori was recovered from the heart and spleen. A guinea-pig, inoculated subcutaneously with an attenuated culture, died on the twenty-fifth day with suppurating buboes and with abscesses in the liver and lungs from which B. whitmori was cultivated. Two horses were inoculated subcutaneously with cultures of the strain of B. whitmori cultivated from the patient. An abscess developed at the site of inoculation, in each case, but the local lesion healed and the animals have, so far, remained healthy.

Case 2. The illness commenced gradually with pain after food, occasional vomiting and looseness of the bowels. The temperature became high and of the swinging type, accompanied by rigors and sweats. The liver was enlarged. The patient died on the twenty-fifth day.

At the autopsy, two large abscesses were found in the liver, the gall-bladder was thickened and there were a few small superficial ulcers in the caecum. B. whitmori was cultivated from the liver abscess. No amoebae were found.

The following animals were inoculated. Two wild rats were inoculated subcutaneously with a culture from this case and both died from septicaemia in less than twenty-four hours. B. whitmori was recovered from the heart's blood. The result of the subcutaneous inoculation of a guinea-pig was the same. A guinea-pig, inoculated in the nostril, died on the fifth day with a cheesy deposit in the nose and septicaemia. Another guinea-pig, inoculated in the same way, but after the organism had been subcultivated repeatedly, died on the twelfth day, with caseous tracheal glands containing B. whitmori. A rabbit, inoculated subcutaneously, died in twenty-six hours from septicaemia with tubereles in the peritoneum. B. whitmori was cultivated from the peritoneum and from the heart's blood. A monkey fed on a culture remained healthy. A pony inoculated intravenously recovered after a week's fever.

This enquiry into the bacteriology of human milk was prompted by our recent investigation of a case of entero-colitis in a breast-fed infant. In this case an abundant growth of a streptococcus was obtained from the faeces of the infant which was identical as far as we could determine with a streptococcus isolated from the mother's milk.

This work was undertaken for the purpose of determining the occurrence and specificity of bacterial precipitins in infections caused by the Staphylococcus aureus. The differences in antigenic properties of various strains of orange and white staphylococci employed in the preparation of the filtered antigens and the importance of the presence of peptone in this connection led to numerous experimental observations which had not been anticipated. The presence of strong S. aureus precipitins in the blood of an adult suffering from very acute serum sickness following an injection of anti-diphtheritic serum led to an investigation of the blood of patients suffering from serum sickness, the results of which are fully recorded here. The investigation of the blood of normal rabbits revealed the fact that in some of these animals staphylococcal precipitins were present, which led to unexpected difficulties in the study of precipitins in the actively immunised animal.

The object of the present investigation was to determine the relation between the variations in hair and eye colours and variations of weight and stature; so that one might know what allowances, if any, would be necessary to make for variations of the proportion of children in different classes of hair and eye colour in different age groups and in the two sexes in the different schools under investigation with respect to the factors influencing bodily growth and nutrition. Incidentally, the analysis might reveal racial differentiation if such were present in this population.

This paper contains an analysis of the results of the bacteriological examinations of 184 samples of milk produced by Mr W. G. Symes, Manor Farm, Fordington, Dorset, between April 1st, 1921 and June 6th, 1924.

The farmer holds a licence to produce Certified Milk which is despatched from the farm in sealed glass bottles. The samples were taken at random from the milk as it was bottled and were at once despatched by post to the laboratory, without placing in cold store. The age of the samples varied from 20–24 hours at the time of examination.

An important aspect of the investigation of bacterial metabolism is the study of the substrate and its changes and of the resulting products; together with an examination of the rate of change. The present report deals with the influence of certain carbohydrates in modifying the action of one species of bacteria upon the protein molecule.

In a study of the influence of environmental and other conditions on the growth and nutrition of the children of the poorer classes in the city of Glasgow, it seemed desirable to determine how far a homogeneous stock was being dealt with since there was some danger that racial variations might modify the results of the investigation.

A technique is described for the preparation of a vaccine from coliform bacilli isolated from the faeces of a patient and agglutinated by his blood serum.

The encouraging results obtained in the treatment of a number of patients suffering from rheumatoid arthritis, chronic rheumatism, and allied diseases with an autogenous vaccine prepared by this technique, are reported.

The absence of agglutinins for coliform bacilli from the blood of healthy persons is established, while it is shown that such agglutinins are present in high concentration in the group of diseases under consideration.

A report is made on the result of attempts to classify the coliform bacilli by cultural and serological reactions.

The facts reported are discussed, and the proposition adduced therefrom that if a patient has in his blood a certain concentration of agglutinins for a coliform bacillus isolated from his faeces, he is suffering from an infection with, or from the absorption of toxins elaborated by, that coliform bacillus, and a vaccine prepared from this organism will probably have a marked curative effect.

Suggestions are made as to the mechanism of infection with coliform baciffi, and as to the significance of variants in that group of organisms found in the faeces.

The impression has always prevailed, that malaria is the most common disease in Palestine, and that it is more or less highly prevalent in all of rural Palestine. This impression, based as it is on mass experience, is in general correct; but it lacks the certainty derived from statistical data.

IN considering the factors which are concerned in the spread of any epidemic bacterial infection among any host-population, the resistance brought into play by the latter will clearly be of crucial importance.

In recent years outbreaks of dysentery and enteritis have been found, on occasion, to be due to late lactose fermenting organisms allied to the Flexner dysentery group. Sonne (1915) found that the main cause of dysentery in Copenhagen was a late lactose fermenting bacillus. D'Herelle (1916) in France and Øhnell (1918) in Sweden also found this atypical organism to be associated with cases of dysentery. Andrewes (1918) suggested the name B. dispar for lactose fermenting members of the dysentery group, which he obtained from cases of suspected dysentery and from convalescents. Thjøtta (1919) in Norway while investigating cases of dysentery obtained 40 strains of Flexner dysentery bacilli (Thjøtta group II) and 25 strains of the Sonne type (Thjøtta group III). He explained that the less frequent finding of the Sonne type was due to the fact that this organism often caused a mild diarrhoea that was not sufficiently serious to necessitate the services of a physician, with the result that the cases were not subjected to bacteriological investigation. He showed that the Sonne bacilli had the following characteristics, viz.: Large irregular crenated colonies grew on litmus lactose agar plates; acid was produced in maltose and glucose, and occasionally in lactose; no indol was produced; and serologically the group showed no relationship to the other groups of dysentery bacilli (Flexner and Shiga).

We may summarise our results, including those recorded in our two recent reports (Topley and Ayrton, 1924 b and c) under the following headings.

(1) The antigenic structure of B. aertrycke (Mutton).

(a) B. aertrycke (Mutton) undergoes natural dissociation into two sharply distinguished varieties, one containing that antigenic constituent which is characteristic of this bacterial species or variety, the other that antigenic constituent which B. aertrycke (Mutton) shares with the bacterial group to which it belongs. We have obtained no evidence that both the type and group antigen may be fully developed in one and the same bacillus. In these respects our results confirm entirely those recorded by Andrewes (1922).

(b) Both the type and the group varieties of this organism, when grown for more than 16 hours at 22° C., or for that length of time at 37° C., tend to undergo an antigenic alteration such that they become agglutinable with an entirely different type of antibody, to which they did not previously respond. The antigen developed as a result of this alteration would seem to be the same for the type and the group varieties. Since plating from such altered cultures gives colonies of the usual type or group variety, it would seem probable that the altered bacilli are dead, dying or senescent organisms.

(c) Although type or group cultures readily give rise to individuals of the alternative antigenic variety in ordinary laboratory media, yet this change is neither so rapid nor so unpredictable in its occurrence that it is impossible to determine the nature of any given colony, or to obtain a culture of the serological variety required.

(d) There is some evidence that type variants arise in group cultures more readily than do group variants in type cultures.

(2) The relations between the presence of type or group antigen and other biological attributes of B. aertrycke.

(a) Roughness and smoothness vary independently of the presence of group or type antigen. Rough forms may react as group or type.

(b) There is no difference between the virulence of the type and group varieties of B. aertrycke. While the virulence of all smooth strains is high, the virulence of all rough strains is low.

(c) There is some evidence that group strains of B. aertrycke give rise more readily to faecal excretion than do type strains, but the difference is not great. Rough strains appear, in this as in other respects, to be ill fitted for a parasitic existence, and do not give rise to persistent faecal excretion.

(d) There is a well-marked tendency for group strains, which have gained access to the tissues, to give place to the type variety. The longer the sojourn in the tissues, the more complete is this replacement. Type strains, under similar conditions, do not tend to be replaced by group strains.

There is a similar, but less marked, tendency for group strains to be replaced by type strains in the intestinal canal.

(3) The excretion of B. aertrycke in the faeces, after administration by the mouth, and its relation to other phenomena of infection.

(a) The excretion of B. aertrycke in the faeces, after administration per os, may be continuous or intermittent, or may not occur in a sufficient degree to be detected by the technique employed.

(b) The faecal excretion, in those mice which succumb to infection, is no more regular in its course than in those mice which survive. It is a frequent occurrence for mice to die with typical lesions of enteric infection, without ever having excreted B. aertrycke in detectable amounts.

(4) The condition of mice which have survived the oral administration of B. aertrycke.

(a) A high proportion of mice, which have survived for 42 days after the oral administration of B. aertrycke, yield cultures of this organism from their spleens when examined post-mortem. In many series of experiments the proportion of survivors showing such positive spleen cultures has exceeded 50 per cent.

(b) The strains of B. aertrycke isolated from the spleens of such survivors appear to be possessed of the normal degree of virulence.

(c) The presence of agglutinins in the blood serum can be demonstrated in only a very small proportion of such surviving mice.

(5) The relation of dosage to the phenomena studied.

(a) With a single dose, there is a definite relation between the number of viable B. aertrycke administered and the frequency of the phenomena indicating infection. The larger the dose the higher is the mortality rate, the more frequent and persistent is the faecal excretion, and the higher is the percentage of the survivors which harbour B. aertrycke in their tissues.

As the dose decreases there is, at first, a rapid fall in the frequency of these various phenomena, but when the dose falls below a certain limit further decreases produce relatively little effect, over the range of doses studied.

(b) Repeated administration of small doses of B. aertrycke results in a high frequency of persistent faecal excretion.

In conclusion we should wish to express our thanks to Miss E. R. Lewis, for her assistance during a large part of the investigations recorded above.