In the annual report of the Chief Medical Officer of the Ministry of Health for 1925 (p. 22) the incidence rates of notifications of pneumonia in four-weekly periods are compared for large geographical groups in England and Wales. These rates show the divergence between the north and north-west and the remainder of the country, and also the fact that the north-west (Lancashire and Cheshire) usually compares badly with the north. During 1923 “in none of the thirteen periods was the rate for the north-west less than 15 per cent, in excess of the all-England rate and in ten it was equal to or greater than the rate for the north.” That these remarks still apply may be seen from the figures for 1930 (Table I). If one compares some of the large Lancashire towns with London the contrast is even greater (Table II). The towns giving the largest number of notifications of pneumonia are Liverpool and Manchester. These towns alone contributed 48 per cent, of the total number of notified cases of pneumonia in Lancashire during 1930. Their combined population forms about 30 per cent, of the total. Great caution is, however, required in drawing deductions from rates of notification of pneumonia, as considerable differences exist between one place and another in the extent to which the obligation to notify is complied with. Mortality rates provide a sounder basis of comparison.

1. Of 585 strains of lactose-fermenting aerobes each isolated from faeces of a different person, 501 did not utilise citrate or ferment cellobiose; 20 were citrate negative and cellobiose positive; 27 were cellobiose negative and citrate positive; and 37 were positive to both tests.

2. Almost 10 per cent, of the strains isolated were indol negative.

3. One culture was methyl-red negative and Voges-Proskauer positive. Two were positive to both tests. The rest were methyl-red positive and Voges-Proskauer negative.

4. It is concluded that the results are not favourable to the use of the citrate or the cellobiose test in routine water analysis.

5. A discussion of the taxonomy of the lactose-fermenting aerobes is given. Only two species, Bacterium coli (Escherich) L. and N., and Bacterium aerogenes (Escherich) Chester, are recognised.

White rats reared from the age of 30 days to 275 days under vita glass, and properly fed, do not grow at a different rate from those reared under ordinary glass.

The offspring of these rats, kept in the same environment, grow at the normal rate when compared with controls born and reared under ordinary window glass.

A short discussion of these results is given in the text.

Addendum. The temptation to use an artificial source of ultra-violet rays having proved irresistible, a further experiment was performed with 20 males, 10 under vita glass and 10 under window glass. These were exposed to the radiation of a Hanovia quartz mercury vapour lamp on alternate days, at a distance of four feet from the burner. The growth curves are shown on Chart V, and the lengths of exposure have been entered on this chart: it will be seen that the results are the same as with natural sunlight.

1. Hydrogen sulphide has been found to have a destructive action on dry anthrax spores.

2. Disinfection of hard, dry, very resistant infected hide specimens, in conditions both of ease and difficulty of access of the disinfecting gas, has been obtained by treatment with hydrogen sulphide at 20° and at 37° C. in periods of 7–16 days.

3. The fact that hydrogen sulphide, in the experimental conditions described, penetrates to the middle of a bundle of leather pockets has been verified by its action in disinfecting (sometimes partially—sometimes completely) anthrax-infected threads placed in the middle of such a bundle.

4. Increase of the temperature at which treatment is carried out has been found to hasten disinfection.

5. Disinfection of anthrax-infected threads has been obtained by treatment with equal parts of hydrogen sulphide and air in 3 days at 60° C.

The author wishes to thank the Council of the British Leather Manufacturers' Research Association for permission to publish this paper, which was submitted to them in the private and confidential report for 1930 of the British Leather Manufacturers' Research Association.

Difficulties in cultivation outside the body have rendered the exact study of the immunity reactions of the filtrable viruses less easy than in the case of many of the bacteria, and the extension of our knowledge of immunity in these infections is at the present time largely dependent upon observation of the behaviour of human beings when exposed to infection through natural channels. For this reason it is important that the utmost use should be made of such reliable statistics as are available for the study of the epidemiology of such diseases as Encephalitis Lethargica and Acute Anterior Poliomyelitis, with a view to understanding their mode of spread and obtaining some clue as to how they may in the future be controlled.

The recognition of small-flaking, granular or “O” agglutination and the conditions under which it occurs have lately assumed importance in the diagnosis and prognosis of enteric infections.

The object of a paper by Fry (1930, p. 313)1 was “to ascertain…the relation of syphilis to malignant disease as determined by the Wassermann reaction.” The conclusion reached (p. 322) was: “In general, from the above figures, there is no evidence that syphilis plays any direct or very important part in the production of cancer.”

1. Spore formation in eight typical members of the genus Bacillus has been studied.

2. Three of these strains, including one species of B. anthracis, have been found to be practically asporogenous under the experimental conditions. In general the following statements hold good for the sporogenous races studied.

3. Spore formation is almost, or entirely, inhibited by cultivation on media rich in amino acids, such as tryptic digests of casein or meat. Similar inhibition results following cultivation on a medium containing reasonably high concentrations of a mixture of amino acids and asparagine.

4. When such media are suitably diluted with standard inorganic salt solutions the percentage of spores formed is greatly increased, and frequently at least 99 per cent. of spores are formed if the dilution is sufficiently high.

5. When simple nitrogenous compounds such as amino acids are added to a dilute casein digest medium in which sporulation is almost complete, a definite decrease in the percentage of spores present is observed. Asparagine, which is probably readily assimilated, apparently completely hinders spore formation in most cases. Other amino acids do not exert so pronounced an effect, and ammonium phosphate does not appreciably inhibit the formation of spores.

6. The fact that the addition of glycine suppresses growth markedly when it is added to a dilute casein digest medium, but does not appreciably hinder sporulation, suggests that the formation of spores is not due to any toxic effect of added compounds, or compounds already present in the medium.

7. Sporulation is almost complete in a “synthetic” medium in which low concentrations of ammonium phosphate and sucrose represent the sources of nitrogen and carbon, respectively. However, frequent transfers in such a medium may inhibit spore formation partially or entirely in certain instances. This effect probably depends upon the enhanced ability of the culture in question to utilise sucrose as a source of carbon when cultivated constantly in its presence.

8. It is concluded, from the above data, that endospore formation in aerobic bacilli bears an inverse relationship to the amount of available nutrient material present in the culture medium.

I am indebted to Prof. Sir F. G. Hopkins and Miss M. Stephenson for their constant encouragement during the progress of this work. My thanks are due to Mr Pirie of this Department who kindly furnished me with several of the amino acids employed, and to Dr Miles of the Department of Pathology for his kindness in supplying me with certain of the cultures.

1. A simple blood-tellurite medium has been described which is absolutely selective for C. diphtheriae and the diphtheroids. In many cases diagnosis at sight of the colonies is possible after 24 hours' incubation. The medium is especially useful for the isolation of carriers when diphtheria bacilli are present in very scanty numbers.

2. The existence of two main types of C. diphtheriae has been confirmed.

(1) The ”lactose+ indol+” index as employed in temperate climate is usually an adequate criterion of water purity.

(2) Where a positive test does not appear to be substantiated by the sanitary findings, a further differentiation of the organisms isolated becomes necessary. The methyl-red and citrate tests have been found to supply that differentiation in a satisfactory manner.

(3) In the Tropics, false positive “lactose-indol” tests are commonly encountered, owing to the presence in large numbers in soil and water of organisms derived from sources other than recently excreted faeces.

(4) In the Tropics, the lactose-indol test should always be confirmed by the methyl-red, citrate and saccharose tests or such other reactions or groups of reactions as may be found by a local survey to be applicable.

My very grateful thanks are due to Dr P. A. Clearkin, Deputy Director of Laboratory Service, Tanganyika Territory, for his ready advice and constant encouragement; and also to Mr W. Whitley, Analytical Chemist, who performed a chemical analysis of the water samples, and very kindly gave me the benefit of his opinion on them. In addition I have to thank Dr R. R. Scott, Medical Officer of Health, and the Staff of the Health Office, Dar-es-Salaam, who have rendered every facility in the choice and collection of samples. It is a pleasure to be able to record once more my indebtedness to Prof. Bigger, of Trinity College, Dublin, whose fund of valuable suggestions and kindly criticism has been ever at my disposal.

In the operations of bacteria under natural conditions it is the general rule to find mixed cultures at work, the variability of the results depending upon many factors. Therefore it has been suggested by Holman (1928) that the general term “bacterial association” be used to cover such processes. When, however, the combined action of two or more micro-organisms effects changes which each by itself is incapable of achieving, the term “synergism” is applied. Synergism appears to be used now in a more restricted sense to describe a particular type of bacterial association, and has been defined by Fiallos (1925) as follows: “two bacilli neither of which causes the production of gas in certain compounds, may do so when artificially mixed together provided one of them is capable of producing acidity (never gas) in these carbon compounds, and the other though inert to these compounds (i.e. produces in them neither acid nor gas) is capable of producing gas from glucose.” In 1911 Penfold observed the production of gas from a glucose medium in which B. typhosus was growing along with a variant non-aerogenic strain of B. coli communis, the latter having been derived from a typical gas-producing culture by selective growth on agar containing sodium monochloracetate. Although this organism had lost the power of gas-fermenting glucose it retained the power of gas-fermenting sodium formate. Castellani (1925, 1926 and 1927) states that he noted the phenomenon, which he calls “symbiotic,” in 1904 when investigating the fermentation reactions of bakers' yeast, which is not a pure culture but consists generally of two or more species of yeasts together with one or more types of Gram-negative bacilli.

The group of organisms included in the term B. mucosus capsulatus has continued to intrigue bacteriologists for more than thirty years, mainly on account of the problems of academic interest which arise when any attempt is made to define the characters of the group as a whole or to classify its members into types. Proof that such problems still exist is to be found in current text-books in which certain discrepancies occur regarding the biochemical reactions ascribed to the various members. There is also uncertainty as to the inclusion of B. lactis aerogenes in the group (Topley and Wilson, 1929; Wilson, 1929). Much of the difficulty arose from the fact that Friedländer's bacillus, one of the first members of the group to be isolated (1883), was studied from a morphological standpoint, while Escherich who described B. lactis aerogenes in 1886 stressed its biological similarity to B. coli. A chasm was thus created between B. lactis aerogenes and Friedländer's bacillus which has not been bridged to the present day, although these organisms must always have resembled, more than they differed from, each other; e.g. Bergey (1929) classifies B. lactis aerogenes with coliform types under Bacterieae and places Friedländer's bacillus in the tribe Klebsielleae Trevisan, i.e. encapsulated Gram negative organisms encountered principally in the respiratory tract, whose fermentation reactions are not given in full. Organisms morphologically similar to Friedländer's bacillus were found to be widely distributed, and in 1896 Fricke named the group B. mucosus capsulatus. There is still little criticism to be made of his general description to the effect that the members were Gram-negative, possessed capsules, showed marked pleomorphism and did not form spores; they grew on a variety of media in a profuse slimy layer, and in gelatin stabs they did not liquefy, but showed the so-called “nail” growth; in addition to this, most of the bacteria classed under this head formed a moderate amount of indole and fermented carbohydrates in solution with production of acid and gas. In an attempt to type members of this group Perkins (1904) admitted that the current knowledge of technique had been almost exhausted in the effort to separate one member from another, but on the basis of certain biochemical differences he was able to distinguish three classes, of which the first was the largest:

1. An epidemic of meningococcal meningitis, due to Type II meningococcus, occurring in a large native population is briefly described.

2. A method of preparing prophylactic meningococcal vaccine on a large scale, and its experimental application in the epidemic is demonstrated.

3. The results obtained in two similar groups of natives, one inoculated with meningococcal vaccine and the other with T.A.B. vaccine, as to the incidence of, and death rate from, meningococcal meningitis are detailed.

1. Bact. aerogenes is practically universally present, although in small numbers in the stools of normal adult humans. The stools of one individual, however, repeatedly gave negative results. The organism has also been isolated from the faeces of horse, cow, sheep, pig, dog, cat, wild rabbit, wild rat and wild mouse.

2. The use of modifications of the citrate medium, containing lithium or barium, is useful in the isolation of Bact. aerogenes when B. pyocyaneus is abundant.

3. Bact. aerogenes predominates over B. coli in soil, the contamination of which by faecal material was unlikely. The B. coli isolated from such soil do not show differences by the tests used from typical faecal strains of B. coli.

4. In the municipal water supply of Liverpool the proportion of Bact. aerogenes to B. coli is relatively high and increases on storage.

5. In water contaminated with faeces, the proportion of Bact. aerogenes to B. coli is relatively low but is rapidly reversed on storage. This is largely due to the death of the B. coli, but may in part be also due to multiplication of the Bact. aerogenes present.

6. Preponderance of Bact. aerogenes over B. coli in a water supply is indicative of either (a) contact with soil which is not contaminated with fresh faeces, or (b) long past faecal contamination.

7. Preponderance of Bact. aerogenes over B. coli in a water supply may, for practical purposes, be regarded as an indication of freedom on the part of the water from pathogenic organisms, including B. typhosus and B. paratyphosus B.

8. The repeated examination of faeces during storage showed a marked increase followed by a gradual decrease in the total number of organisms present. The decrease coincided with an increase in the numbers of Bact.aerogenes relative to the organisms present. Whether an absolute increase in the numbers of Bact. aerogenes occurred, was not determined.

9. A plea is made for uniformity among the tests adopted by future workers for the identification of coliform organisms, and an exact statement of the methods employed.

The writer desires to thank Prof. J. M. Beattie for helpful advice throughout the course of the investigation.

1. The epidemic spread of plague in Java usually shows periodicity in that the increase commences in the third quarter, the driest period of the year, the apex being reached in the last months of the year. Afterwards, still in the middle of the wet monsoon, the decrease commences and reaches its lowest point in the second quarter.

2. This seasonal course of plague—in the mountainous parts of Java at least—corresponds with a distinct fluctuation in the flea index during the same period.

3. Whereas under the climatic conditions of the mountainous regions of Java the flea index usually follows the rise and fall of the saturation deficiency, it has been shown that in British India the influence of the saturation deficiency is in an exactly opposite direction.

1. Human and guinea-pig sperms are susceptible to the most diverse chemicals to almost the same degree.

2. There exists a substance in human semen which protects both human and guinea-pig sperms against certain chemicals, especially sodium oleate, orthovanillin and potassium borotartrate.

3. When perfectly fresh human semen is not available, the spermicidal powers of substances may be tested by using guinea-pig sperms suspended in human semen which has been kept cool.

The present investigation, was undertaken to test the American suggestion that the higher mean concentration of haemoglobin in males in America, compared to this country, is due to the chronic inhalation of carbon monoxide from the exhaust of closed motor cars (Price-Jones, 1931).

An examination of some 10,000 tumour-bearing mice appertaining to 240 experiments comprising 24,000 animals has been made to find whether there was any difference in sensitiveness of the skin to our carcinogenic agents, according to colour of coat and eyes. Methods involving only elementary arithmetic have been utilised as we have, unfortunately, no statistical mind on our staff, and thus we have, presumably, failed to derive full benefit from the data available. We have ventured, however, to draw the following tentative conclusions as regards the particular animals under discussion, they being obtained from varied sources:

1. Self-coloured animals (excluding pure white) were more sensitive to petroleum oils (weak agents) than the corresponding piebald. (That is, a black was more sensitive than a black and white, etc.)

2. When tars (strong agents) were utilised instead of petroleum oils an opposite state of affairs existed, the self-coloured animal being more resistant than its piebald companion. This reversal may be explained on the grounds of cell tolerance.

3. Pink-eyed animals (excluding pure white) had a greater all-over sensitiveness of the skin to our agents than pigmented-eye animals.

4. On the whole the most sensitive animal was the pink-eyed fawn.

5. The frequency of hyaline degeneration of the spleen and marked thyroid enlargement was greater among pink-eyed animals, especially when fawn coloured, than among pigmented-eye animals.

Methods for measuring the temperature and humidity of the air beneath the shirt are described.

Conditions of temperature and humidity under the shirt are described, for a resting person, with external temperatures varying between 0° C. and 41° C., under different atmospheric humidities. The air beneath the shirt varied between 23° C. and 37° C., and 23 and 70 per cent. relative humidity. The saturation deficiency of the air beneath the shirt varied very little—only between 13 and 18 mm.—in all the observations taken.

I am indebted to Dr P. A. Buxton for many helpful suggestions and for reading the manuscript. Also to Prof. G. H. F. Nuttall, F.R.S., for drawing my attention to literature on the earlier work.