A study has been made of the bacterial flora in the sewage supplied to, and the effluent from, the bacteria beds which deal with the liquors produced at the Coventry gasworks. A high count in the effluent from the beds of bacteria containing an oxidase system, or a relatively large increase in the viability of such organisms when compared with the original sewage, has been found to be concurrent with good purification in the beds, and vice versa.

The bacterial flora undergoes considerable modification in the beds, and also when mixed with 4 per cent, of its volume of spent liquor in the laboratory. The total viable count of the treated sewage is reduced under these conditions, but the count of those bacteria which give the direct oxidase reaction and therefore catalyse the oxidation of catechol is relatively increased.

A gram negative vibrio (strain 0 1) is the only bacterium isolated which has proved capable of breaking down monohydric phenols. It has been constantly isolated from the effluent liquors.

Gasworks' ammonia liquor in the relatively high concentrations used exerts a markedly toxic action on all types of sewage bacteria, and the purification of this liquor by the beds is not so satisfactory. The toxicity is probably caused by the highly alkaline reaction of the liquor.

This investigation was commenced by one of us (F. C. H.) in conjunction with Dr Allan C. Monkhouse, who was at the time Research Chemist to the Liquor Effluents Sub-Committee of the Institution of Gas Engineers. Dr Monkhouse accepted another appointment shortly after the commencement of the work, and was therefore unable to assist further, but we should like to express our indebtedness to him during the initial period. We are also indebted to Prof. J. W. McLeod and Prof. J. W. Cobb for their kindly interest and encouragement, and to Mr P. N. Langford, Engineer and Manager of the Coventry Gas Department, for the facilities he so generously placed at our disposal at Coventry.

One of us (F. C. H.)is in receipt of grants from the Medical Research Council, and would again express his thanks to that body.

One of us (A. K.) is indebted to the Liquor Effluents and Ammonia Sub-Committee of the Institution of Gas Engineers for permission to publish this work.

1. Seven strains of Strept. mucosus are described which have the following characteristics: large “mucous” colonies on serum agar and other media referred to in the text, with a subsequent particular form of lysis; no growth occurred on gelatin at 22° C., although the organisms were still viable on this medium after 10 days at this temperature; inulin was fermented and milk acidified without any clot formation; the organisms were only partially soluble in bile.

2. All our strains were isolated from patients suffering from acute infections of the respiratory tract.

3. Inflammatory and suppurative lesions were produced in rabbits and guinea-pigs by inoculation of the live organisms.

4. Vaccines may prove highly toxic when injected subcutaneously even in small doses into patients suffering from these infections.

5. Immune sera containing precipitins were formed in rabbits inoculated with the live organisms, but not when filtered toxins or dead cultures were employed.

6. Precipitin antigens were obtained by high-speed centrifugalisation of serum-broth cultures until the supernatant fluid was glass clear, and from centrifugalised suspensions in saline from egg cultures, but after filtration of the cultures through a Seitz filter or Berkefeld V candle the filtrates were inert.

This paper gives some account and results of work conducted on the properties of ethylene oxide, as this compound has been recommended as an insecticide and vermin destroyer, and what is of more importance, as a fumigant for foodstuffs. The concentration recommended is in the nature of 2 lb. per 1000 c. ft. (or 1 part in 60) for 24 hours. It has also been mentioned as a possible agent for use as a lachrymator in war.

A strain of Proteus vulgaris, recovered from a case of cystitis, showed extreme pleomorphism in a primary culture on ordinary agar.

Pleomorphism was not found in sub-cultures on media free from added NaCl, but it appeared in the presence of a limited range of NaCl concentrations; with still higher concentrations it was not observed, although growth occurred. It was rarely found in cultures which grew with difficulty.

Pleomorphism, occurring under the conditions mentioned as to salt concentration, was most marked in young cultures which grew vigorously; it usually disappeared as the cultures aged; and it became less and less evident in serial sub-cultures on medium containing the same amount of salt.

The morphology of the organism differed on different media, e.g. filamentous on salt-free agar, short bacillary on MacConkey's agar, but it was practically constant in repeated sub-cultures on any one type of medium.

Pleomorphism could be re-induced on any of the media used by suitable alteration of its NaCl content (increase or decrease). Pleomorphism was not determined by variation of the H-ion concentration of salt-free media; nor by variation of the temperature of incubation of cultures; nor by growth in fluid media as opposed to solid media.

After nearly 4 years under laboratory conditions the organism is still sensitive to variation in the NaCl concentration of its environment, as evidenced by pleomorphism; but pleomorphism is now less extreme than it was originally.

Pleomorphism is still most marked in young sub-cultures on media with suitably altered salt concentration, but it is sometimes difficult now to induce pleomorphism unless a stock culture several weeks old is used as the inoculum.

The pleomorphism comprises aberrant forms similar to many of those which are regarded by certain observers as evidence of stages in a life cycle; but, in the case of the organism described, these forms can be induced by the simple expedient of altering the salt concentration of the medium on which it is grown. The occurrence of such forms is thus, of itself, no proof of a life cycle.

1. Whooping cough is now in London the most important epidemic disease of childhood in causing physical suffering, loss of school attendance, impairment of physique and mortality.

2. The mean annual incidence of whooping cough in children under 10 in Battersea during the quinquennium 1925–9 is estimated to have been about 60 per 1000 living, and the fatality rate 1·26 per 100 cases. The fatality rates in the first two years of life were estimated to be 4·0 and 3·3 respectively, at ages 2 to 5, 0·7 and at ages 5 to 10, 0·2 per 100 cases.

3. Epidemics of whooping cough in Battersea and Greenwich tend to have a biennial periodicity; a summer epidemic is often immediately followed by or merges into a winter epidemic subsiding by midsummer, and then follows a year of low incidence, so that the total incidence of cases in successive years from midsummer to midsummer shows an alternation of epidemic and interepidemic years.

4. Epidemics do not always run concurrently in areas of London separated by several miles; the spread is checked to some extent by barriers to free communication and small districts thus occasionally escape an epidemic, or an interval of several months may separate the epidemic peaks in districts a mile or so apart.

5. The view that the epidemic cycle in whooping cough can be explained by a periodic reduction of the proportion of children not previously attacked below some critical limit, is shown to be untenable. Both the termination of epidemics and their periodicity can be explained by the occurrence of a latent immunisation of contacts as in measles, such immunity only lasting about 1 year instead of 2 or 3.

6. The occurrence of such a transient latent immunisation is indicated by (a) measurement of the rise and fall of apparent infectiousness of cases to other children in the same house during 6 years in Battersea, (b) measurement of the frequency of second cases in houses after different intervals of time during a decade in Greenwich, and (c) analysis of the attack rates amongst home contacts in Holborn and Battersea during several years following exposure to infection as compared with those among control groups of children. These phenomena would be difficult to explain as resulting from a “cycle of activity” of the organism.

7. In London as a whole a special enquiry into the previous histories of school entrants proves that 44 per cent. of children have an attack of whooping cough before their fifth birthday. According to Battersea records 27·7 per cent. are notified or reported to the Public Health authority as having whooping cough by this age, and 42·3 per cent. by the tenth birthday. It is concluded that in that borough about 60 per cent. of the true incidence is notified at ages under 4, about 72 per cent. at age 4, and 90 per cent. at ages 5 to 10 when school supervision is fairly complete. At all ages under 10 the recorded incidence in Battersea represents about 70 per cent. of the true incidence.

8. It follows that about 60 per cent. of London children have whooping cough by the tenth year, and about 61 per cent. at some time during life, this proportion being rather lower than estimates made from histories given by parents in a group of American towns. The bulk of the remaining 40 per cent. must escape attack by virtue of some kind of immunity rather than by avoidance of contact with infection through life, and a part of these no doubt escape by the repeated acquisition of transient latent immunity during epidemics, and the remainder by virtue of an inherent immunity to the disease.

9. During the year following an epidemic the proportion of children under 10 who are susceptible is approximately doubled and again halved during the next epidemic. This must be mainly due to temporary latent immunisation during an epidemic of x children to each one attacked, the value of x lying between the limits 1 and 4, this depending upon the unknown proportion who are inherently immune. If the bulk of the two-fifths of all children who escape attack have inherent immunity, as is suggested but not proved by the data, then the ratio of latent to recognisable infections lies between 1 and 2.

10. Superposed upon the gradual rise and fall of infectiousness believed to be due to these immunity changes, there occurs a sudden rise at the commencement of an epidemic which must be attributed to an enhanced real infectiousness. This probably arises from a sudden increase in activity of the organism itself under seasonal influences setting in at the moment when the herd immunity becomes insufficient to withstand the infection pressure, so that the balance is upset and the epidemic begins.

11. These findings are similar to those for measles, the chief differences being, (i) epidemics are usually spread over a year instead of 6 months; (ii) latent immunity apparently lasts about a year instead of 2 or 3; (iii) about 60 per cent. of children are attacked at some time during life instead of about 90 per cent.; (iv) there is probably inherent immunity in a certain proportion, but not in measles; (v) the ratio of latent to manifest infections is lower.

We are indebted to Miss M. Kirby for drawing the diagrams in this paper. Towards the expenses of this research a grant was made by the British Medical Association.

1. The outbreak of typhoid fever in the Ecclefechan Special Water District affected 55 per 1000 of the inhabitants (primary cases only).

2. The evidence available indicated the public water supply as the vehicle of infection.

3. A typhoid carrier was found employed in the water-collecting area.

4. Examination of the water pipes after excavation showed that surface pollution might gain access to the pipes conveying spring water to the collecting tank.

5. Secondary cases were few in number, and so far there is no evidence that foci of infection remain as sequelae of the outbreak.

The physiological reactions of two subjects were investigated in air at a temperature of 70–100° F., and of 40–96 per cent. relative humidity. The experiments lasted 3 hours, and one of the subjects performed mechanical work (step climbing) at the rate of 14,000 kg. m. per hour.

The pulse rate was about 10 beats greater in dry air than in moist air of the same wet-bulb temperature. The winter observations agreed well with the effective temperature scale, but did not agree with the wet bulb, the dry-bulb or the kata-thermometer scales.

Acclimatisation effects showed themselves in experiments made at a dry-bulb temperature of 87° F. or more, but only very slightly in those made at 81° or less. Acclimatisation was fairly well marked in the summer, the pulse rate being 5 to 10 beats less than in the winter, and no longer agreeing with the effective temperature scale.

The body temperature corresponded with the pulse rate, for it was 0·3–0·6° F. higher in dry air than in moist air of the same wet-bulb temperature, and was 0·15° lower in summer than in winter. The winter observations agreed well with the effective temperature scale.

The skin temperature of the face was found to depend on the dry-bulb temperature of the air, but that of the trunk showed no agreement with any of the scales. In moist air it was 1° F. lower than that of the face, and in dry air, 6° lower, owing to the cooling effect of increased sweating.

The gross mechanical efficiency fell off slightly at temperatures above 70 or 75° F. It was affected by the dry-bulb temperature of the air as well as the wet bulb, but not to the extent indicated by the effective temperature scale.

The weight of moisture lost by sweating corresponded well with the effective temperature scale. It increased gradually in consecutive experiments made in dry air, and diminished in those made in moist air.

The degree of fatigue experienced in dry air was considerably greater than in moist air of the same wet-bulb temperature, and it corresponded with the effective temperature scale.

Acknowledgments. We wish, to express our indebtedness to the authorities at the London School of Hygiene and Tropical Medicine, and especially to Dr G. P. Crowden, for the facilities offered to us in our work.

This investigation has been undertaken at the request of the Birmingham Committee of the British Empire Cancer Campaign. The chemical work has been carried out under the general advice of Prof. W. N. Haworth, F.R.S., in the Department of Chemistry, and the work on the clinical side under Prof. G. Has well Wilson, M.D., in the Department of Pathology.