In recent years immunity reactions have come to be regarded more particularly from the physico-chemical standpoint. Many of the phenomena occurring in immunity reactions are shown to be of the nature of colloidal chemical processes, and the laws which govern such processes have been found to hold, at least partially, for reactions occurring in sera, which belong to the class of colloidal protein solutions. Thus the application to immunity reactions, of such conceptions as viscosity and surface tension, has afforded a more reasonable explanation of these reactions. In the following paper special reference will be made to the surface tension, changes of which play an important part in all immunity reactions.

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).

A new salmonella subgenus I serotype is described. Strain C.S. 1608/73, serotype 67: r: 1, 2, was isolated from activated sewage sludge and was assigned the name S. crossness. The serotype is biochemically atypical in its ability to utilize sucrose and this ability appears to be controlled by a transferable plasmid.

Hepatitis A infection results in a spectrum of illness from asymptomatic disease to severe fulminant hepatitis. Since 2000, <50 cases have been reported annually in Ireland. We report on an outbreak of hepatitis A associated with a childcare facility(CCF) in 2015 in Ireland. Between January and July 2015, 12 outbreak-associated symptomatic hepatitis A cases were identified, including one delayed, retrospective diagnosis. Seven (58%) cases were adults, eight (67%) were male, six of the adults required hospitalisation. All 12 cases were confirmed on serology and the four cases that were genotyped were identical on phylogenetic analysis. Potential environmental exposures and hygiene practices at the CCF were investigated. Outbreak control measures included the provision of: hepatitis A information, infection prevention advice, hepatitis A vaccination to 554 CCF contacts, and voluntary closure of the CCF for deep-cleaning and staff education. From a healthcare perspective1, outbreak control costs were in excess of €45 000. This outbreak illustrates the considerable adult morbidity that can occur in hepatitis A outbreaks, highlights the challenges in controlling a large CCF-associated outbreak and the importance of early recognition by clinicians of hepatitis A.

Plague was introduced into Queensland from Sydney in 1900, and every subsequent year has been marked by an outbreak in Brisbane. In both towns the authorities are unsparing in their efforts to eradicate the factors contributing to its maintenance, but in both places the infection of the rats and their haunts is so extensive that the disease may now be looked upon as endemic in the two cities. The probabilities are, however, that the pest will be harder to eradicate in Sydney, where the buildings are substantially built, and not as in Brisbane light structures of wood which more easily lend themselves to treatment and are comparatively temporary in their character.

Although knowledge of principles determining variation is imperfect, some progress has been made and further help may be obtained from some of the newer conceptions about combining affinities regulating normal growth. There are reasons to believe that growth depends on a rhythmic cycle of synthesis, peculiar to living protein, whereby at each successive stage one particular “building stone” is selected for synthesis, with rejection of all others. There is also some evidence that the surface of a growing bacterium passes through periodic phases. Additional light on the activities of the bacterial surface is thrown by the new conception of enzymes which regards them not as fixed chemical entities but as chemico-physical “centres of activity.”

Some of the principles which are gradually coming to light in bacterial variation may ultimately be of assistance in the much more obscure problem of explaining the change from the normal mammalian cell to its malignant variant. I refer in particular to conceptions, which I have discussed in the preceding part of this article, about the mechanism of cellular growth and the nature of a cell's combining affinities.

In a previous paper it was shown that of the empty milk churns which were examined, 56 per cent, were totally unfit for use, as they contained very large numbers of bacteria and lactose fermenting organisms in high proportion. Table I (1) is taken from this paper and gives the number of bacteria per 1 c.c. of washings with sterile saline solution. These churns were taken at random on a station platform, their origin being unknown.

In analysing some samples of air which had been sent for examination, the writer was struck by the presence of an altogether abnormal quantity of carbon dioxide associated with a very much diminished oxygen content. In view of this excess, the space from which these samples had been obtained was then thoroughly ventilated and after remaining closed for only four days the air was found to contain already 2·27 p.c. of carbon dioxide instead of the normal 0·03 p.c. No immediate explanation of the phenomenon was available and this paper contains a short account of the research made to discover the cause.

The experience of the last few years in the Westphalian coal-field has shewn that the presence of Ankylostoma in a mine may become a matter of considerable industrial importance. Since it has been shewn that several of the metalliferous mines in Cornwall are throughly infected, the question of how far it may be present in, or spread to, other British mines has arisen in a practical form. When any large number of individuals have to undergo a medical examination for any such purpose it is of importance that such examination should be convenient at once for the examiner and for the examinee, that it should occupy as short a time as possible, and should, at the same time, be reliable. The diagnosis of the presence of Ankylostoma is commonly made by searching for the characteristic eggs in the faeces; and indeed a final diagnosis must rest in nearly every case on the results of this procedure. Which is therefore not easily replaced by any other method when separate individuals are in question. But as applied to a large body of active working men this process has many disadvantages, and at the request of the Home Secretary an inquiry has been made into the practicability of other methods of examination1.

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.

In the Berkefeld filtration of a fresh guinea-pig serum, adsorption on the filter surface takes place, and the serum passes unaltered, if the saturation of the adsorbing surface has become complete.

This adsorption involves most probably first the albumins, which process then secondly influences the filtrability of the globulins. It is also shown that the physical conditions of the serum as regards salt concentration and dilution as well as H.-concentration modify the effect of filtration to a large extent.

1. A retrospective survey has been made to determine the amount of cross-infection caused by Staphylococcus aureus of one particular phage-type, 83 A, in four main hospitals of a provincial hospitals group, over a period of 2½ years.

2. The total number of strains considered was 1131. Of these, 776 were resistant to tetracycline and therefore the most likely to be of significance in cross-infection. Of these 776 strains, about one-third belonged to phage-type 83 A. In the hospital where 83 A strains were most prevalent, they formed about one-half of the tetra cycline-resistant strains; in that where they were least prevalent, about one- quarter.

The clinical sources of the tetracycline-resistant strains are described.

3. It was found that type 83 A strains were the most likely to show resistance to erythromycin, chloramphenicol or novobiocin.

Of a series of 214 type 83 A strains sensitivity tested against methicillin, using a disk-plate method, none was found to be resistant.

My thanks are due to Prof. R. E. O. Williams, St Mary' Hospital Medical School, for his helpful criticism of this paper and, in his previous capacity as Director of the Staphylococcus Reference Laboratory, Central Public Health Laboratory, Colindale, to him and his staff for supplying me with typing phages, and instructing me in their use. I should also like to thank Dr M. T. Parker, Director of the Cross Infection Reference Laboratory, Colindale, for a continued supply of these phages; the Hon. the Viscount Waverley, F.R.C.P., for allowing me to quote from the case history of a patient under his care; and Mr K. Allen, F.I.M.L.T., and other members of my technical staff for their assistance.

1. ACTH, cortisone, sphingomyelin and sphingosine produce a delayed in-hibition of the skin reaction in cattle sensitized to Trichomonas foetus antigen when they are injected intramuscularly. The inhibition is greatest 6–9 hr. after injection of the inhibitor, but may sometimes be further delayed. This reaction is associated with an absolute lymphopoenia of slightly variable duration.

N-acetylsphingosine retains the desensitizing effect of crude sphingomyelin and is of much the same potency as cortisone acetate of Merck.

2. The lymphopoenia associated with the injection of ACTH and cortisone occurs also with sphingosine, and these three substances are also alike in not producing the desensitizing effect until some hours after the injection.

3. Phenergan, a synthetic anti-histamine, has a different action, and its desensitizing effect which appears to depend on a direct antagonizing of the oedema-provoking substance resulting from the junction of antibody and antigen (hapten) takes effect apparently as soon as the injected drug itself is present at the site of the injection of the specific testing fluid.

4. Methods of testing the capacity of the hormones and drugs to prevent the skin reaction locally and to nullify the action of the in vitro antigen-antibody mixtures which can produce a reaction in normal animals are described.

Phenergan alone of the substances dealt with has any power to act locally. Phenergan mixed with the antigen-antiserum complex in vitro prevents the formation of the characteristic swelling in a normal animal.

Phenergan mixed with the specific testing fluid prevents the development of the skin reaction when the mixture is injected intradermally into a sensitive animal.

Cortisone and sphingosine do not have this action.

We are indebted to the Medical Research Council for supplies of ACTH and cortisone and to Sir Charles Harington for N-acetylsphingosine.

The personal encouragement of Prof. H. G. Lamont and the support afforded by the Ministry of Agriculture, Northern Ireland, are gratefully acknowledged.

1. Temperature influences the rate at which glycerinated lymph deteriorates in accordance with the law of Arrhenius, expressing the effect of temperature upon chemical action; the rate of deterioration increasing three times per 10° rise in temperature.

2. Dry powdered calf vaccine in sealed glass capillary tubes still gave rise to typical vesicles after exposure to a temperature of 100°C. for from 5 to 10 minutes.

3. The vaccine virus can withstand positive osmosis for 24 hours or more, and negative osmosis for 8 weeks or more, at room temperature.

4. It appears doubtful whether the vaccine virus will pass through a Berkefeld V filter even when a stored vaccine emulsion is used for filtration. If any virus does pass through it only does so exceptionally and in small quantities.

5. When a glycerinated vaccine emulsion is filtered, white flocculi frequently form in the filtrate. These are at first minute, but subsequently adhere and form a macroscopic sediment. This sediment, when inoculated on calves, does not cause vesiculation.

Microscopically these flocculi, in hanging drop preparations, resemble the vaccine bodies described by one or more observers.

There is some suggestion that infection with pandemic influenza may increase long-term mortality risks. Therefore we aimed to determine if exposure to a severe outbreak of pandemic influenza on a troopship in 1918 impacted on lifespan in the survivors. The troopship with the outbreak cohort had 1107 personnel and the comparison cohort was from two contemporaneous troopships (1108 randomly selected personnel). Data were collected from online individual military files. The main finding was that there was no statistically significant difference in the lifespan of the outbreak cohort and the comparison cohort (means of 71·5 and 71·0 years, respectively). Indeed, the outbreak cohort was actually more likely to survive into the period from 1950 onwards (P = 0·036) and to participate in the Second World War (P = 0·043). There were no significant differences between the cohorts in terms of occupational class, but the comparison cohort had a higher proportion of rural occupations (33·3% vs. 27·0%, P < 0·001) and was very slightly older in mid-1918 (27·8 vs. 27·2 years, P = 0·028). In conclusion, this study found no support for the hypothesis that exposure to the 1918 influenza pandemic adversely impacted on the lifespan in the survivors, at least in this male and military-age population.

Arising out of the routine selection of wheat germs for the production of a composite high-value and reasonably uniform mixture, it has been found that the variation in the vitamin B activity of unselected wheat germ is greater than has been generally suspected.

Formic aldehyde, the simplest possible aldehyde, is a substance possessed of considerable biological and chemical interest. Its biological interest consists in the fact that it has long been regarded as forming the first product of plant assimilation, and has recently been actually demonstrated as such in plants. The ease with which this substance undergoes polymerisation resulting in the formation of sugars, under the influence of simple reagents, justifies the assumption that formic aldehyde is an essential link in the building-up of complex carbohydrates by plants. In addition to this it has recently been requisitioned as the only possible source of proteid anabolism. Its interest to the physiological chemist is that it combines energetically with proteids, and to a less extent with carbohydrates, effecting considerable alteration of their physical and physiological properties. This behaviour seems to be directly antagonistic to the biological rôle ascribed to the substance above. This apparent anomaly of the same substance being both a poison and an essential physiological constituent of living cells is discussed by Loew. It seems to depend upon the fact that what may be termed the biological formic aldehyde is present in small quantities (dilute solutions) and is quickly used up, owing to the ease with which it polymerises or forms innocuous compounds. This last property has an immediate bearing upon the subject of this inquiry in so far as it may serve to explain the results obtained by the administration of small quantities of formic aldehyde to man in his food. It is in this connection that formic aldehyde is of interest to us, and the importance of this subject is in our opinion sufficient to justify us in reviewing somewhat exhaustively the results of other observers with regard to the chemical and physiological properties of this substance.

Given the challenges in accurately identifying unexposed controls in case–control studies of diarrhoea, we examined diarrhoea incidence, subclinical enteric infections and growth stunting within a reference population in the Global Enteric Multicenter Study, Kenya site. Within ‘control’ children (0–59 months old without diarrhoea in the 7 days before enrolment, n = 2384), we examined surveys at enrolment and 60-day follow-up, stool at enrolment and a 14-day post-enrolment memory aid for diarrhoea incidence. At enrolment, 19% of controls had ⩾1 enteric pathogen associated with moderate-to-severe diarrhoea (‘MSD pathogens’) in stool; following enrolment, many reported diarrhoea (27% in 7 days, 39% in 14 days). Controls with and without reported diarrhoea had similar carriage of MSD pathogens at enrolment; however, controls reporting diarrhoea were more likely to report visiting a health facility for diarrhoea (27% vs. 7%) or fever (23% vs. 16%) at follow-up than controls without diarrhoea. Odds of stunting differed by both MSD and ‘any’ (including non-MSD pathogens) enteric pathogen carriage, but not diarrhoea, suggesting control classification may warrant modification when assessing long-term outcomes. High diarrhoea incidence following enrolment and prevalent carriage of enteric pathogens have implications for sequelae associated with subclinical enteric infections and for design and interpretation of case–control studies examining diarrhoea.