1. Calculated values of the virtual sterilization time (v.s.t.) have been used in an analysis of the effect of temperature on the concentration exponent of the reaction between phenol and Bact. coli cultures under rigidly standardized conditions.

2. Within the experimental range of temperature and concentration employed, the exponent calculated from the formula Cn × t = K was satisfactorily constant from 20° to 35° C., but it apparently increased at 39° C.

3. This formula is unsatisfactory in that it cannot apply to concentrations near the threshold value without a change in the value of n. Accordingly, a new method of treating these data has been suggested which makes allowance for this threshold or minimum concentration. A corresponding ‘maximum’ concentration has been arbitrarily fixed at which the v.s.t. is 10 min. and the value of (v.s.t. – 10) thus varies from infinity to zero between these concentration limits.

4. Sigmoid curves asymptotic to ordinates at the minimum and maximum concentrations must be obtained when log (v.s.t. – 10) is plotted against concentration and the equation of the Pearl-Verhulst logistic curve, which is of the required type, has been used successfully to express the relationship between v.s.t. and concentration at constant temperature.

5. One of the constants of this formula partakes of the nature of a concentration exponent and this may be constant over the full effective concentration range and for all temperatures.

6. The logistic formula relating v.s.t. to concentration at constant temperature is closely related to that connecting v.s.t. with temperature at constant concentration. The two formulae become interconvertible if certain assumptions are made concerning the relationships between the minimum and maximum concentrations and temperature.

1. The laboratory findings in a series of 215 cases of enteric fever are described and discussed, with special reference to early diagnosis.

2. In the majority of the cases reviewed, the leucocyte count was about the lower level of normal limits, though considerable variation both upwards and downwards occurred.

3. Blood culture was a very satisfactory and early method of diagnosis; the method used is described fully.

4. Certain variations from normal in the behaviour of the organisms were encountered and are described.

5. Bact. faecalis alkaligenes was isolated from blood culture in five cases in which enteric group organisms were also isolated from blood, faeces or urine and in three which were clinically enteric fever. The relation of these observations to the possibility of primary Bact. faecalis alkaligenes septicaemia is noted.

6. Seventeen cases were fatal. The causes of death are described.

The Schick test was carried out on 500 recently confined women and their new-born infants. The Schick reaction was positive in as many as 73 % of the mothers and in 60 % of their infants. The infants were positive reactors in 82% of all the cases in which their mothers were positive.

The reaction of the new-born infants was, as a rule, weaker than that of the mothers. It often happened that when the mother's reaction was faintly positive, her infant's reaction was negative.

When the mothers had been immunized with diphtheria toxoid, the overwhelming majority of both the mothers and their new-born infants were negative. Immunization of Schick-positive women with diphtheria toxoid during pregnancy is recommended as a preventive of diphtheria in infancy, as by this means the antitoxin level of the new-born infant can be raised.

We wish to acknowledge our indebtedness to Jörgen Lövset, M.D., chief physician, Hospital for Gynaecology and Obstetrics, Bergen, Norway, for permission to use the material for this investigation.

1. In vitro experiments carried out by a modified Rideal-Walker technique showed the superiority of CTAB over chlorine and chloroxylenol disinfectants against Str. agalactiae.

2. The disinfectant action of 1 % CTAB persisted on the surface of dry hands and cows' teats for a period of at least 3 hr. Subsequent moistening of the hands with milk reduced the efficiency of this disinfectant.

3. For the prevention of dissemination of Str. agalactiae by means of milkers' hands and at the same time to reduce the incidence of infection on the surface of teats, a lanette wax-oil base containing 1 % CTAB was tested. It was found that the inclusion in the cream base of CTAB did not reduce its bactericidal efficiency.

1. Solubility of a germicide in the medium (water or air) in which it is operating appears often to be the most important physical characteristic governing degree of activity on bacteria (partition law).

2. Evidence of the importance of solubility has only been derived from a study of the action of phenols and glycols, a high bactericidal activity never being registered unless solubility was low.

3. Other types of germicide were exceptional in that high solubility coincided with high bactericidal activity: iodine and maleic anhydride in the air; mercuric chloride and many organic acids in the test-tube.

4. Mixtures of germicide and bacteria as used in the test-tube were sprayed into the air, the bactericidal effect being usually increased or decreased according as to whether it was originally low or high in the test-tube.

5. The vapour pressures of most of the germicides used were deduced from the Clausius and Clapeyron formula, the boiling-points being determined by the bubbling method.

6. When the amount of a phenol used in the air is approximately proportional to the vapour pressure, the bactericidal effects of the different samples are more nearly parallel when the degree of saturation of the air is low than when it is high.

7. No phenol with a vapour pressure lower than 0·0021- mg. Hg, and tested at full saturation, sterilized the air during the first minute of the experiment, while all samples with, at least, 10 times this vapour pressure did so when at 12·5 % saturation.

8. Among the phenols tested, especially those having low vapour pressures, the concentration (w/w) in air is very much less than the concentration in water in the respective experimental conditions, where but few survivors is the criterion of efficacy. Owing to a number of different factors, the rapid decline in the initial concentration is more likely to be met with under air than under test-tube conditions.

In the present work it is suggested that the sterilization of bacterial suspensions by mercurial antiseptics is a reflexion of a possible stoichiometrical relation between the mercuric compound and the thiol receptors in the bacterial cells.

This has been verified experimentally by studying the times of survival of suspensions of B. typhosum mixed with multiples and submultiples of the quantity of antiseptic theoretically equivalent to the thiol content of the suspension, as estimated by iodometric titration.

The considerable differences observed in the time of survival of suspensions mixed respectively with more and with less than the thiol equivalent of antiseptic, and the absence of any marked effect of dilution of the mixture, show that there is a quantitative relationship between the amounts of substrate and the quantity of antiseptic capable of sterilizing it.

1. The sizes of the droplets and droplet-nuclei produced by sneezing, by coughing and by speaking, were studied by the microscopic measurement of 12,000 droplet stain-marks found on slides exposed directly to mouth-spray, and of 21,000 stain-containing droplet-nuclei recovered from the air on to oiled slides exposed in the slit sampler.

2. From these measurements it was calculated that the original diameters of the respiratory droplets ranged from 1 to 2000 μ, that 95 % were between 2 and 100 μ and that the most common were between 4 and 8 μ. Similar size distributions were exhibited by the droplets produced in sneezing, in coughing and in speaking, except that, in the case of sneezing, the smaller droplets were relatively more numerous.

3. The respiratory droplet-nuclei were found to range in diameter from ¼ to 42 μ; 97 % had diameters between ½ and 12μ; the commonest diameter was between 1 and 2 μ.

4. The proportion of droplets of each size which will contain bacteria, whether commensal or pathogenic, is determined by the size of the droplets and by the numbers of bacteria in the secretions atomized. Calculations made on the basis of the size distributions obtained in this investigation indicated that few of the smaller droplets, and thus few of the droplet-nuclei, are likely to contain pathogenic organisms. Droplet-spray is unlikely to give rise directly to true airborne infection unless very large numbers of pathogenic organisms are present in the secretions of the anterior mouth.

5. The persistence of droplet-nuclei in the air of a 1700 cu.ft. room and of a 70 cu.ft. chamber was investigated by sampling the air with the slit sampler at intervals following sneezing.

6. When the air was not artificially disturbed by a fan, the time taken for the disappearance from the air of 90% of the bacteria-carrying droplet-nuclei varied from 30 to 60 min.; the nuclei larger than 8 μ in diameter usually disappeared within 20 min., and the nuclei larger than 4 μ within 90 min.; the smaller nuclei, few of which contained bacteria, remained airborne for much longer periods, on one occasion for at least 30 hr. When a fan was run throughout the experiment, the nuclei disappeared from the air much more rapidly.

The present inquiry was undertaken to obtain some indication of the relative frequencies of deaths amongst infants from the various forms of diarrhoea and enteritis—‘neonatal’, ‘parenteral’ and ‘infectious’—in the Greater London area in the decade before the war. Since much of the material needed for such an analysis was not available in the published records, a sampling inquiry, making use of the more elaborate records maintained by the Medical Officer of Health, was undertaken for the Borough of Willesden. A comparison of the relevant epidemiological and social conditions in this borough with those in the Greater London area as a whole showed, that for such a purpose, it might properly be regarded as a representative sample.

There was little evidence for the occurrence of the neonatal form in Willesden during the period studied, nor did the seasonal distribution of the deaths suggest that many took place in consequence of preceding parenteral infections. On the other hand, there did seem to be some evidence that a significant proportion of these deaths were in some degree associated with one another, in time or place or both, and it is suggested that this distribution might have resulted from the widespread dissemination in the community of one or more strains of some common micro-organism of relatively low virulence for all but the infant population.

A less detailed study of data for other London boroughs, viz., Bermondsey, Croydon, East Ham, Tottenham and West Ham, supported the main conclusion reached from the Willesden records.

1. General considerations relating to the feeding of laboratory animals are discussed.

2. A cubed diet suitable for growing and stock rats and mice is described, together with wire-mesh, containers adapted to various types of cage.

3. The consumption and requirement of these cubes by growing rats and mice is recorded.

1. Fresh greenstuff is not necessary for rabbits, provided that drinking water is supplied.

2. A dry diet has been evolved which gives very satisfactory results with rabbits when supplemented only by hay and water.

3. Dry diet in the form of pellets is much more acceptable to rabbits than an identical diet in the form of meal.

4. The presence in the diet of 30% of even poorquality dried grass seems to supply an adequate amount of ascorbic acid, and the exogenous requirement of rabbits for this vitamin must therefore be very small.

5. Confirmation of the toxic effects of cod-liver oil for rabbits is given.

Growth of bacteria in an infusion of flax under quiescent conditions resulted in the formation of an acidic liquor with an appreciable content of volatile acids. When a similar infusion was aerated by a continuous current of air, the liquid tended to become alkaline and the content of volatile acids was much smaller and in some cases negligible. Aeration reduced the polluting strength of the liquor, as measured by oxygen absorbed from permanganate and by the biochemical oxygen demand, by much larger amounts than did growth under quiescent conditions.

Experiments with infusion in which the natural flora was allowed to grow, and with sterile infusion inoculated with pure strains of different types of bacteria, showed that the general effect of aeration was to alter the metabolism of the bacteria in the direction of more complete oxidation of the substrate. Balance sheets for carbon showed that the organic carbon lost from the culture was accounted for by the CO2 evolved. Thus carbohydrates, which under anaerobic conditions were fermented to organic acids, neutral volatile compounds, and gases, were oxidized, when the conditions were sufficiently aerobic; to CO2 and water.

The magnitude of the effects observed depended largely on the nature of the organisms present, and partly on the strength of the infusion in which they grew. With pure cultures of Bact. coli, Bact. aerogenes and Bacillus subtilis, and with the natural mixed flora of the flax, aeration at moderate rates in bottles for 3–5 days reduced the value for oxygen absorbed from permanganate by 43–52 %, and the biochemical oxygen demand by 26–92 %, indifferent experiments. The organic carbon content of the infusion was reduced by 30–31 % by Bact. aerogenes, by Bacillus subtilis and by the mixed flora. With streptococci and with a strain of Achromobacterium the effects observed were very small. Aeration at higher rates with diffused air in small open tanks reduced the organic carbon content of a flax infusion by 50 % in about 80 hr., and of a beetroot infusion by 50 % in about 60 hr. Sugar was destroyed during the aeration and disappeared rapidly from the flax infusion in the early stages.

The work described in this paper was carried out in connexion with an investigation of retting of flax and disposal of waste waters, made, as an extramural research, for the Ministry of Supply as part of the programme of the Water Pollution Research Board of the Department of Scientific and Industrial Research. The paper is published by permission of the Chief Scientific Officer, Ministry of Supply, and of the Department.

1. A clinical and biochemical study of a group of thirty patients from northern Portugal shows that they were suffering from a mild form of pellagra with no signs of severe malnutrition or of associated deficiencies except dental abrasion caries and pyorrhoea.

2. The diet of these patients in most respects was chemically satisfactory. Apart from a very low consumption of animal protein the gross intake of calories, total protein minerals and vitamins, including nicotinic acid, was satisfactory.

3. Since the syndrome was completely cured by nicotinic acid, it is suggested that the main characteristic of a diet on which pellagra is likely to develop is not a shortage of nicotinic acid, but a lack of high-grade protein.

4. A maize diet, satisfactory so far as calories and total protein are concerned, may produce pellagra because maize proteins are short of certain essential amino-acids. Other cereal diets may also produce pellagra if the general level of nutrition is very low.

5. The syndrome may be cured either by very large doses of nicotinic acid without change of diet or by moderate doses accompanied by abundant animal protein.