1. The air of four large scarlet-fever wards was found to contain large numbers of haemolytic streptococci, most of which could be identified serologically. In one ward the serological types identified were found to correspond the types infecting patients in the ward.

2. The degree of infection of the air with haemolytic streptococci showed considerable variation during the 24 hours. During the night, infection was absent or negligible, in the morning there was a steep rise followed by a slight fall in the degree of infection during the early afternoon. This variation is probably associated with the degree of air movement in the ward produced by the ward staff in the execution of their duties.

3. Haemolytic streptococci were widespread in the ward air and the serological types identified were not confined to the neighbourhood of patients infected with a particular type.

4. Though contact with infected hands, instruments, books, toys, etc., is probably of considerable importance in the transmission of infection with Strept. pyogenes, and though droplet transmission no doubt occurs as in other infections of the respiratory tract, yet the possibility of infection via the air cannot be dismissed, especially in multiple-bed wards in which patients infected with many different serological types of haemolytic streptococci are being nursed.

The trend of fertility in Wales and the Southern and Midland counties of England was demonstrated and discussed in the previous sections of this enquiry.1 The corresponding vital statistics for Northern England are given in the present concluding section and, in addition, the results that have been found are briefly reviewed for the country as a whole. For the Northern counties the same methods have been employed as in the two previous sections. Briefly, the actual birth-rate has been measured by the number of births per 1000 married women aged 15–45, while as a rough assessment of how far a changing age distribution of married women has affected its level, a potential birth-rate and fertility ratio have also been calculated. The potential birth-rate gives the number of births per 1000 married women aged 15–45 obtained by applying Tait's fertility ratios 48.75, 41.25, 30 and 15 to the number of married women in the age groups 15–19, 20–24, 25–35 and 35–45 respectively. The fertility ratio is the ratio of the actual to the potential birth-rate.

In recent years, it has become apparent that lesions of the suprarenal glands occur more often in human disease than had formerly been suspected. The evident effect of such lesions is the production of profound general disturbances, which are seen in a chronic phase if the morbid process in the suprarenal tissue is slowly progressive, as, for example, in the ordinary case of Addison's disease, and in an acute phase if the lesion is of sudden onset, as in suprarenal haemorrhage, or if chronically diseased suprarenal tissue is subjected to sudden excessive demands, as in the critical stage of Addison's disease. In both phases, there is evidence to show that the best measures to employ in combating these disturbances, whether for prophylaxis or for therapy, consist of the administration to the patient of an extract of suprarenal cortex or, alternatively, of sodium chloride.

1. The term “reinfection” has been defined as the secondary infection of a scarlet fever patient during hospitalization with Str. pyogenes belonging to a serologically different type from that producing the primary infection.

2. Of forty-seven scarlet fever patients nursed in a multiple-bed ward and swabbed twice weekly during their period of isolation, thirty-three (70.2 per cent) became reinfected with a serological type of Str. pyogenes different from that causing the primary disease.

3. In fifteen out of the thirty-three patients reinfected, the reinfection was “latent”, i.e. gave rise to no clinical signs, while in the remaining eighteen the reinfection was “manifest”, i.e. was accompanied by clinical signs or complications.

4. Patients nursed in cubicles or in a ward confined to infections with a single serological type did not show reinfection; their convalescence was progressive and there were no late complications.

5. The majority of complications occurring during the third week of hospitalization and subsequently, in multiple-bed wards devoted to scarlet fever, are due to reinfection.

6. Most reinfections occur during the third week in hospital at a time when patients are as a rule convalescent from their primary infection.

7. The most frequent mode of transmission of reinfection appears to be by direct contact of patient with patient.

8. Ten instances of “relapse” in scarlet fever (only three in the present series) are quoted; in all of them the patients were nursed in multiple-bed wards. In each instance the “relapse” coincided with the isolation of a fresh serological type of Str. pyogenes from the throat, and must therefore be regarded as a second attack of scarlet fever.

9. The various systems of nursing patients in isolation hospitals are discussed and it is suggested that scarlet fever patients should be cubicle-nursed if possible. Failing this they should be nursed by the bed-isolation method in multiple-bed wards. By setting aside small wards it might be possible to keep together patients who are all infected by the same serological type of Str. pyogenes; the number of such wards would vary with the number (usually three or four) of epidemic types current at the time.

1. The experimental data obtained by Greenwood et al. (1936) relating to epidemics of the virus disease ectromelia in mice have been examined in the light of mathematical theory. Attention has been directed in particular to the life tables calculated from the observed data, which give the chance of survival and death after various periods of cage life.

2. The life table relating to ectromelia 1 during the steady state phase from 1. iii. 32 to 31. viii. 32 shows very close agreement over the range 0–550 days with that predicted by the theoretical equation which involves only four arbitrary constants. A slight discrepancy over the first few days is evidently due to the fact that representation of the death-rate and the recovery rate by constant coefficients does not accommodate an incubation period. The values of the constants obtained from the data give a measure of the essential characteristics of the epidemic.

3. General agreement, though not so complete, is also found when the theory is applied to ectromelia 2 during the priod 1. xi. 31–30. iv. 32. During this phase however, although conditions were otherwise apparently uniform, a steady state had not actually been attained. On the other hand the equations do not apply so satisfactorily to the obviously inhomogeneous period 1. v. 32–20. x. 32.

4. In the present analysis the assumption of constant rates gives a satisfactory account of the progress of an infection in a susceptible community. This result suggests that for many purposes the assumption of constant rates may be adequate.

5. The short period fluctuations observed in the ectromelia epidemic were probably random in character and have no relationship to periodic fluctuations such, for example, as those detected by Brownlee in the case of measles.

There is much evidence to indicate that viruses, in certain cases at least, have an antigenic structure of comparable complexity to that of the bacteria. Hughes (1933) found that the serum of animals immunized with the yellow-fever virus contained two independent antibodies—precipitins and protective antibodies; the precipitinogen was distinct from the virus. Craigie & Wishart (1936) in investigations of the vaccinia virus have shown that, in addition to the elementary bodies, virus suspensions contain two soluble precipitable substances, the “L” antigen which is labile at 56° C. and the “S” antigen which is stable at 95° C. These antigens were readily demonstrated by precipitation, agglutination and complement fixation. Their nature and origin have not, however, been precisely determined. Bedson (1936), working with the psittacosis virus, prepared a soluble antigen, which was independent of the elementary bodies. It was most satisfactorily demonstrated by complement fixation.

From results obtained from the twenty-two patients with essential hypertensions we find that their CO2 and O2 subcutaneous tissue gas tensions lie within normal limits. Thus (1) there can be no thickening of the capillary walls, and (2) the blood flow through the capillaries is normal.

1. The fall in the refractive index of mineral oils recovered after injection into the peritoneal cavity of mice is usually accompanied by a fall in the density proportional to the fall in the index.

2. With straight distillates from the crude oil the ratio of index fall to density fall is on an average about 0·85 to 1. Wide deviations from these figures were rarely found except when dealing with oils of low toxicity. The ratio tends to be above the mean when the actual index fall is low and consequently below the mean when the index fall is high.

3. The refractivity of the original oil, the index fall of the recovered oil and the density fall of the recovered oil give information as to the carcinogenic potency for mice of the original oil of about equal value, but the two lastmentioned tests are far superior to the first for assessing the probable dermatitic potency of the oil.

4. Other things being equal, the index and density fall are closely dependent upon the index, density and viscosity of the original oil.

5. The index and density fall gradually become larger as the experiment progresses, but within each 24-hour interval the fall gradually becomes less. The ratio of index fall to density fall remains fairly constant for each individual oil during the course of the experiment.

6. Titration of mineral oils in vitro with sulphuric acid and alcohol provides residual oils of lower index and density than the original oil, but the ratio of the fall in index to the fall in density is low, especially when the treatments are not severe.

7. Oxidation of mineral oils tends to raise the density without affecting the index to an appreciable extent. On the other hand reduction tends to lower the index without affecting the density to anything like the same extent.

8. In general terms the animal reacts upon the chemically treated oils in an additive manner, so that if by the chemical treatment we have the ratio of index fall to density fall low, the oil recovered from the animal will have the ratio high, and vice versa. The end product of the severe treatment of a mineral oil with acid and clay is a white oil which for practical purposes may be considered to be fully saturated. The end product of an oil recovered from the animal is probably similar in nature, although the process involved in arriving at this end product is presumably different chemically and physically.

9. Synthetic oils recovered from the animal after inj ection showed a marked rise in density but no corresponding rise in index.

10. The animal reaction to an injected oil was not materially accelerated by emulsification of the oil.

11. Some chemically pure non-carcinogenic compounds were very rapidly changed or eliminated from the peritoneal cavity.

12. All alcohol extracts of mineral oils tested showed an increase in index, density and refractivity, but not always in viscosity compared with the original oil, the residues, of course, having characteristics in an opposite direction. The latter were in every instant less toxic for the animal than the original oil, whether applied to the skin or injected.

13. A mineral oil recovered from animals 7 days after injection, when reinjected into a second series of animals, was altered as regards its physical characters in a normal manner. Thus whether allowed to remain in the peritoneal cavity of an animal of the first series or recovered and reinjected into an animal of the second series, the ultimate index and density fall in a given time were approximately similar.

14. The free oil in the peritoneal cavity becomes, from day to day, less. This is at least partly due to local trapping by the proliferating endothelium. The fall in index of the trapped oil is approximately similar to that of the free oil.

15. The alteration of the physical characteristics of mineral oils by the animal is probably brought about by a chemical reaction followed by removal of the changed product.

During the last few years a considerable amount of experimental evidence has accumulated which indicates the importance of chemical structure in determining the specificity of both natural and synthetic antigens. This work has been summarized by Marrack (1934), Landsteiner (1936) and Morgan (1936), and it is therefore not proposed to discuss in detail the investigations which have contributed to our present-day conception of this aspect of immunity reactions. Contributions which seem essential for understanding the ideas developed in this communication will, however, receive mention.

The diameter of the virus of rabbit fibroma has been estimated by filtration through graded membranes to be about the same as that of vaccinia (125–175 mµ) and by centrifugation to be 126–141 mµ.

That of the rabbit papilloma virus appeared by filtration to be 23–35 mµ and by centrifugation 32–50 mµ.

The consumption of water and milk in the form of beverages, fluid foods and foods to which water or milk was added in cooking was determined over a period of a week in early spring in two Public Assistance Institutions containing 166 adults and 3 children aged 9–13 years. The results obtained are summarized in Table II. The consumption of water in the form of solid foods could not be estimated directly, but was calculated from the results obtained from quantitative dietary studies of ten working-class families whose diet was adequate. The intake of water in solid food was calculated as 0·97 pint for males and 0·80 pint for females per head daily. Water formed in oxidation was assumed to be 300 c.c. per head daily for men and 250 c.c. for women. The total water consumed and formed in the body was therefore probably in the region of Men 4·93 pints (2799 c.c.) per head daily, Women 5·08 pints (2885 c.c.) per head daily.

The amounts of water lost by the kidneys, bowel, skin and lungs are tentatively suggested and tables of water balance are put forward as approximations to the water requirements and exchanges of normal people. The water supplies of the institutions are soft and the amounts of calcium consumed in water were very small and are probably not of much nutritional significance. Hard waters are, however, probably of some importance as sources of calcium, especially when the diet otherwise is poor in this mineral.

The amounts of milk consumed per head daily were in excess of 0·5 pint and the amount of calcium consumed in the form of milk amounted to more than half the standard requirement for adults. The calcium intake in both institutions was probably adequate.

The variation in fertility between different sections of the London area has been, and in spite of the decline, still is, considerable. In London as a whole the birth-rate has fallen by 56 per cent since 1870–2, while the potential rate shows a decline of only 6 per cent. The fertility of the boroughs is highly correlated with the index of their social status. A higher birth-rate is recorded in the areas with a large proportion of unskilled or semi-skilled labour, a lower birth-rate in the areas with a high proportion of the professional and more affluent members of society. Other indices of relative poverty and wealth and hygienic conditions give a similar answer. The decline in fertility during the past 20 years is not sensibly related to these indices but appears in its rate to have been broadly equivalent throughout the area.

1. Streptococcus pyogenes multiplies readily in sterilized milk stored at 22 and 18° C., and more slowly at 15° C. In fresh raw milk this organism begins to multiply slowly only after 48–72 hours of storage at 18–22° C. In laboratory pasteurized milk the result is similar, but both commercially pasteurized milk and raw graded milk bottled for distribution sour too rapidly for multiplication to take place after artificial contamination. These facts suggest that widespread epidemics are rarely due to extensive multiplication of S. pyogenes in milk during commercial or household storage.

2. The initial degree of contamination of milk with S. pyogenes has no influence upon this organism's ability to multiply during storage.

3. The failure of S. pyogenes to multiply during storage is due to (a) its natural reluctance to grow at atmospheric temperatures, (b) the bacteriostatic action of the milk, and (c) the readiness with which saprophytic bacteria multiply at atmospheric temperatures.

4. It is contended that infected cows play a major part in the spread of milk-borne S. pyogenes epidemics, and relevant literature is quoted to support this view. It is urged that routine investigation of apparent milk-borne epidemics should include the immediate bacteriological examination of an individual sample of milk from every cow concerned in the supply under suspicion.

It was Heraclitus who said of his predecessors that they had much knowledge but no sense, and this criticism often comes to mind when workers pause in retrospect and wonder that the application of the quite adequate knowledge of a generation ago was not applied in a practical and wise manner. Perhaps it may seem that a long time elapsed after compulsory education was adopted before it was realized that a vast number of children were physically quite unfitted to benefit from the learning presented to them; and it was a still longer time before it was hesitatingly acknowledged that the art of living, the teaching of an hygienic way of life, was the most important aspect of education. For without this the benefits of the whole system are of little lasting worth or real utility. Thus it is that open-air education, born late in time, is of such paramount importance; because although ordinarily and primarily conceived for restoring delicate children to health, the main great permanent value of this work is that it teaches in a practical and pleasant manner the greatest of all arts—the art of living.

The introduction of preventive inoculation against typhoid and paratyphoid, and in particular its widespread application during the Great War, caused considerable difficulty in the interpretation of the Widal test. It was often impossible to decide whether the agglutinins demonstrated were due to active infection or to previous inoculation.

The designation, Newington, is proposed for those cultures of S. anatum having the antigenic formula III XV: eh: 1, 4, 6. A new type, New Brunswick, is described which is represented by the formula III XV: lv: 1, 7 +. Attention is called to the inadequacy of the symbols currently employed in the representation of the non-specific antigens to express correctly the non-specific phases of the Nyborg and New Brunswick types.

Although attempts to produce an active immunity against diphtheria were made as early as 1902, it is since the Schick test was described in 1913 that there has been available some clinically applicable measurement of individual immunity, naturally obtained or artificially produced; and it is probably true to say that large-scale active immunization has been practised in this country for only some 10 or 15 years.

1. Horgan's (1936) findings with regard to heat sterilization of B. typhosus vaccine are not confirmed.

2. Silver in the form of katadyne or electro-katadyne appears to be an effective sterilizing agent for B. typhosus suspensions.

3. Katadyne and electro-katadyne have no destructive action on Vi, O or H agglutinogens of B. typhosus.

4. Electro-katadyne, even when used in excessive doses, has no detrimental effect on the immunizing activities of Vi antigen.

5. Electro-katadyne sterilized suspensions of V strains of B. typhosus are more effective immunogenic agents than those sterilized by heat and phenol.

6. The bactericidal properties of electro-katadyne, though impaired in 0·85 per cent saline, are adequate as a means for preserving vaccine.

7. It is suggested that katadyne sterilized suspensions of V strains might be of value in testing for the presence of Vi agglutinins in human sera since they are hypersensitive to Vi antibody while retaining most of their resistance to O antibody.

8. In view of the suggestion by Felix that additional antigens with activities similar to those of Vi antigen may exist in bacteria other than B. typhosus, it may be found that the electro-katadyne process has an application in the preparation of vaccines generally, particularly those which have hitherto proved ineffectual in prophylaxis.

Crystalline histamine picrate and hydrochloride have been prepared from cotton dust. The melting-points and crystalline structure found are in agreement with those obtained by other workers.

The blood histamines in sixty-five card-room workers have been estimated and compared with the figures found in 103 students and eighteen elderly chronic bronchitics. The figures for the three groups are shown in distribution figures, and the card-room workers have, on an average, a higher blood histamine than both groups of controls. It has, however, to be admitted that the differentiation of card-room asthma from other respiratory diseases on the basis of the level of blood histamine cannot be guaranteed in individuals.

1. The view is advanced that the endotoxin of the meningococcus is one of a group of thermostable intracellular bacterial poisons, and that it is not a specific antigenic toxin. 2. The inability of the “endotoxin” to function as an antigen does not lessen its importance as a pathogenic factor in cerebrospinal fever, since the lesions that are associated with the presence of the meningococcus in the tissues are apparently attributable to the pyogenic action of the intracellular poison.