1. The efficiency of plating of phage 13 on the semi-resistant strain Ps. LIII-3bi decreases as the initial bacterial population on the plate is diminished. Addition of Ps. LII extract to the phage before plating with low bacterial concentrations increases the plating efficiency (exhibition effect).

2. An extract of a strain Ps. LIII-lb which is fully sensitive to phage 13 also causes exhibition of this phage on Ps. LIII-3bi.

3. It is suggested that dissolved phage 13 receptors present in extracts of Ps. LII and Ps. LIII-lb have an affinity not only for the phage but also for suitable bacteria and thus cause exhibition. Inhibition (e.g. of phage 14 by the Ps. LII extract) is due to phage receptors having no tendency to adsorb to bacteria.

4. The phage-exhibiting and inhibiting properties of a freeze-dried extract of Ps. LII active when dissolved in 0.85 % NaCl are lost if the solid is dissolved in water and the solution so obtained further diluted with 0.85 % NaCl. Activity is recovered slowly if NaCl is added to the aqueous solution, instantly if the solution is freeze-dried and the residue dissolved in 0.85 % NaCl.

5. The inhibitory properties of the Ps. LII extract for phage 14 are more sensitive to heat and acidity or alkalinity than the exhibitory properties for phage 13.

6. The absence of cross-precipitin reactions between Ps. LII and Ps. LUI-lb suggests that the phage 13 receptors of the two organisms are non-antigenic or different. I am grateful to Prof. M. van den Ende and my colleagues in this Unit for helpful discussions.

By ultracentrifugation of emulsions of brains from suckling mice infected with the MEF1 strain of poliomyelitis virus, infective virus can be separated from a non-infective soluble antigen. The soluble antigen which remains in the supernatant fluid is serologically specific and is responsible for most of the complement fixation shown by such brain emulsions.

Soluble antigen is not demonstrable in the brains of adult mice infected with a strain of the virus which has not been adapted to sucklings.

The soluble antigen is heat stable and resists treatment with organic lipoid solvents such as acetone, ether and chloroform.

Four litters of newborn piglets suffering from haemolytic disease of four different grades of severity, were observed clinically. Pallor and mild jaundice were evident in some cases, but the activity of the piglets was not reduced except in the terminal stages of fatal cases. Malnutrition affected a number of piglets sometimes from fortuitous factors. In mild cases there were no clinical symptoms, and the disease could be detected only by demonstrating a fall in haemoglobin level or sensitization of the red cells.

Several blood group systems were concerned in the genesis of the disease in these piglets and both agglutinating and incomplete antibodies were shown to be present in the piglets' circulations; in one case antibody was found in the piglet's circulation only 3½ hr. after suckling started, and by 4 hr. the titre of free antibody was 256. The antibodies did not pass the placenta.

In severe cases a rapid fall in haemoglobin, interrupted by a sharp, transient rise, and accompanied by reticulocytosis and erythroblastaemia, was characteristic of the first 24 hr.; this was followed in some cases by a prolonged low level of haemoglobin before recovery started.

In some of the animals that died, severe and widespread focal necrosis of the liver, together with degeneration and necrosis in the kidney, were marked. Pigment deposits and erythrophagocytosis were common in nearly all organs but abnormal extramedullary erythropoiesis was not observed.

A number of haematological, serological and biochemical findings are recorded.

The potency of tetanus toxin as measured by combining power is markedly reduced by mixing with fresh or dried preparations of rabbit brain, and by dried horse brain. A number of other bacterial toxins are not so affected.

Tissues other than brain were not found to have this specific effect.

The state of division of the tissue, the time over which adsorption takes place, and the relative proportions of adsorbate and adsorbent affect the quantity of toxin removed. When the quantity of adsorbent and the volume of adsorbate are constant, the quantity of toxin removed per gram of adsorbent is proportional to the equilibrium concentration of the toxin, but not directly so.

Some of the tetanus toxin adsorbed onto fresh or dried preparations of brain tissue can be recovered by washing with physiological saline.

Brain toxin mixtures, when treated with tetanus antitoxin, neutralized an amount of antitoxin about equivalent to the toxin retained by the tissue.

Successive adsorption of tetanus toxin by brain tissue leads to an alteration in the ratio L + per ml./Lf per ml. of the toxin.

The adsorption capacity of brain tissue may be reduced by first washing with tetanus toxoid or heated toxoid or with diphtheria toxoid.

Stored mixtures of the virus and corresponding antisera in foot-and-mouth disease have equal complement-fixing activity whether they are prepared from virus and serum of homologous or heterologous types. On ultracentrifugation the complement-fixing activity is removed from the mixture and the remaining antibody is more sharply type-specific in routine complement-fixation tests than the original serum.

Against the concept that starch is inert immunologically and, therefore, an ideal substrate for in vitro studies on leucocytes, the results here recorded demonstrate that there are at least two components of serum which are specifically required for phagocytosis of starch. The available evidence suggests that the heat-labile component is C′, and the heat-stable component is specific Ab. The latter, which is a serum globulin, conforms to the definition of Ab from three standpoints: (1) it is adsorbed to the starch granule at low temperature and cannot be eluted by washing with saline at pH 7–0; (2) although it is found in ‘normal’ serum, it appears in increased quantities in the serum of animals injected with starch; and (3) once combined with the starch granule, it exerts three in vitro immunological effects, i.e. opsonization, induction of immuneadherence, and agglutination. As evidence that the latter reactions are due to specific Ab, the enhancement of phagocytosis and the induction of immune-adherence are manifested only in the presence of C′.

The measurement of Ab or C′ has been complicated by the finding that fresh normal serum to be employed as C′ has invariably contained Ab to starch. This situation is similar to that which exists with a variety of micro-organisms, e.g. Micrococcus aureus, against which the majority of normal animals and human beings possess circulating Ab. To obtain C′ free of Ab, fresh guinea-pig serum was adsorbed in the cold with starch. Despite the low temperature which would be expected to reduce the C′ fixation, about 30–40% of C′ activity was lost during adsorption for 60 min. at 0° C. When the adsorption was performed in the absence of Mg2+ and Ca2+, the loss of C′ was lessened considerably. This is interpreted to mean that at least two factors contributed to the loss of C′ cited above: (1) the specific fixation of some or all components of C′ to the starch-Ab complex, which requires the presence of Mg2+ and Ca2+, and which occurs even in the cold; and (2) the non-specific action of starch in adsorbing C′, or perhaps destroying C′, which does not require Mg2+ or Ca2+.

1. The protection afforded by glycine and other amino-acids to guinea-pig complement against heat-inactivation is increased in the presence of sugars, although the latter are not themselves protective.

2. No significant increase in protective activity occurs in the presence of the alcohols derived from some of the sugars tested.

3. A marked exception amongst the alcohols is inositol, which reinforces the protective power of glycine at least as much as do the sugars.

4. The fourth component of complement is destroyed by heating at 63° C. for 30 min. It is, however, protected against heat-inactivation by glycine, and this protective effect is intensified in the presence of glucose and inositol.

5. The protection afforded to serum by the presence of glycine or glycine dissolved in glucose is removed when the system is dialysed, indicating that if a complex is formed it is readily dissociable.

It is generally agreed that the administration of the 11–oxysteroid hormones of the adrenal cortex to the commonly used experimental animals, the rat and the rabbit, produces involution of lymphoid tissue. Since lymphoid tissue is an important site of formation of antibody, several workers have attempted to correlate the effects of adrenal steroids on lymphoid tissue with their effects on immunity. The effect of the 11–oxysteroid adrenal hormones on the immunity of experimental animals, as judged by the amount of circulating antitoxin present in the blood, is not, however, a matter of general agreement. Different workers have obtained widely diverse and conflicting results.

1. Pival at 0·025% is somewhat less toxic than warfarin at 0·005% to R. norvegicus when ingested for periods up to 72 hr. It is also less acceptable in a dry cereal bait.

2. Pival and warfarin at 0·025 % are about equally toxic and equally acceptable to R. rattus.

3. Young R. rattus appear to be more resistant than heavier rats to both Pival and warfarin.

4. The fungicidal properties of Pival are discussed.

1. It has been confirmed that Trichomonas foetus fails to survive freezing and thawing in the presence of 10 % glycerol in egg-yolk-citrate diluent. Under the same conditions adequate sperm survival was demonstrated.

2. Trichomonads were particularly sensitive to the toxic effects of glycerol when suspended in egg-yolk citrate.

3. Trichomonads will survive freezing and thawing when suspended in other diluents such as egg-yolk phosphate or milk.

This report on a large outbreak of disease, known locally as ‘Chikungunya’, in the Newala district of Tanganyika concerns the circumstances of isolation of strains of virus, some of their properties, and their relation to the epidemic. The work, reported here, started in Newala from 18 February to 10 March, 1953, and continued thereafter in Entebbe.

1. Myxomatosis was first recorded in England in October 1953 and persisted over the following winter. It was anticipated that an epizootic, similar to those in Australia, would develop during the spring or summer of 1954 and that mosquitoes might be the principal vectors. A study of the sylvan mosquitoes in the area of the first myxomatosis outbreak was therefore made, from April 1954 onwards.

2. These mosquitoes (Aëdes spp.) overwinter as larvae, pupate in early May and are adult from mid-May to September. Throughout this period, in 1954, myxomatosis spread slowly in the study area and infected rabbits were abundant.

3. Despite the presence of large numbers of Aëdes (particularly A. cartans and A. annulipes) and their persistent attacks upon man, the mosquitoes (except in one case) were not attracted to healthy domestic rabbits exposed in the woods. Aëdes can have little, if any, part in the spread of myxomatosis. Observations made in the cool summer of 1954 were confirmed in the hot summer of 1955.

4. Engorged mosquitoes (apart from those which had just fed on the human collector) were never found, so precipitin tests could not be made. The source from which these woodland mosquitoes normally obtain their blood meals remains a mystery.

5. In the laboratory, the Aëdes were reluctant to feed on normal, healthy rabbits but fed readily (round the eyes and on the nose) on normal anaesthetized rabbits or comatose myxomatous rabbits. Biting experiments indicated that Aëdes may remain infective for up to 36 days after an infective blood meal.

6. Infected Aëdes were recovered from woods containing myxomatous rabbits, and tame rabbits infected by the bites of these mosquitoes developed myxomatous tumours on the nose. Although some Aëdes were thus feeding on wild myxomatous rabbits, the evidence that the mosquitoes did not feed on healthy rabbits indicates that Aëdes were of negligible importance as vectors of myxomatosis.

To show that blood-sucking insects can transmit viruses which cause human diseases, human beings themselves must be used for experiments, or, as this is rarely possible, their place must be taken by suitable laboratory animals. For this purpose an animal species must be available with the following attributes: it must regularly circulate much virus in its blood after infection, and it must be susceptible to infection by the intracutaneous inoculation of a small dose of virus. None of the animal species available possess these attributes during experimentation with many human viruses. Insect transmission can often then be demonstrated by using the indirect method described in this paper.

Silicic acid in its polymerized form is toxic to leucocytes in tissue culture and depresses leucocyte respiration, effects which appear to be paralleled by its inhibition of the cytochrome oxidase enzyme system. There is evidence that silicic acid acts on this system by combining with and inactivating cytochrome c and it is suggested that its effect in vivo may have a similar basis. The inhibitory effect of silicic acid on the two other respiratory enzyme systems studied is considerably less intense and probably non-specific.

Evidence is presented that outbreaks of myxomatosis among domestic rabbits at Newhaven in Sussex were spread through the agency of Anopheles atroparvus. The habits of this insect are discussed in relation to its possible importance as a vector of myxomatosis.

The evidence presented supports the hypothesis that the experimental form of anthrax induced by depositing a cloud of single spores on lung epithelium is initiated in the lymphatic regions and not in lung tissue.

Proportionately few of the deposited spores reach the lymph glands. The majority remain inactive in so far as induction of disease is concerned. Slowly, however, they seem to go through the first stages of germination but do not multiply and therefore die. This is probably the major factor operative in their disappearance from the lung.

Effective prophylactic measures are suggested for dealing with an unimmunized host exposed to anthrax infection by the pulmonary route.

Anopheles labranchiae atroparvus which have gorged on myxoma-infected rabbits may retain their infectivity for as long as 220 days in a period covering the winter months. Virus titres in infected mosquitoes may also remain stable for several weeks at summer temperatures; virus has been recovered after 36 days in summer.

Virus in these Anopheles is, in most instances, to be found only in the head and mouthparts. Survival on mouthparts of killed mosquitoes, on the other hand, has been only for a few days.

One strain of virus (Newhaven strain) isolated from wild A. atroparvus produces flat erythematous lesions on intradermal inoculation into rabbits, and deaths occur later than with typical strains.

The possible role of over-wintering atroparvus as a reservoir of infection of myxomatosis is discussed.

The possibility is considered that transmission of infection by Anopheles is not purely mechanical, but that limited multiplication occurs in the insects.

The preparation of purified influenza virus from infected allantoic fluid is described, and its fractionation by ether treatment with the production of pure samples of soluble antigen and haemagglutinin.

Chemical analysis of intact infective virus showed it to have a nitrogen content of 9.3%, a carbohydrate content of 3.5%, and a content of ribonucleic acid of 0.7–0.74%.

Purified soluble antigen derived from the infective virus particle was shown to be a ribonucleoprotein containing 5.3% RNA. No carbohydrate other than ribose was found. Purified haemagglutinin was shown to be a mucoprotein containing 4.2% of a polysaccharide possibly composed of galactose and mannose in equimolar proportions.

The LD50 dose of Past. pestis is much greater when tested by the respiratory route than by subcutaneous challenge. This is probably due to trauma inflicted on the airborne particles.

Two forms of plague, both originating in the respiratory tract of the guinea-pig, can develop according to the size of the particle containing Past. pestis presented to the host. Small particles initiate a broncho-pneumonia which leads to septicaemia and death. Large particles establish a septicaemia, and death results more quickly without the development of a pneumonia.

Cross-infection to normal animals occurs irregularly when they are exposed to others developing plague by the respiratory route. Such incident is rare when the initially infected animals are exposed to large particles. Cross-infected animals suffer from the disease characteristic of exposure to large particles. Attempts to establish an epizootic by cross-respiratory infection were abortive, probably due, in some measure, to the type of disease developing in first cross-infections.

1. The characters of twenty-seven strains isolated from sheep in New Zealand and Australia were examined and compared with those of representative strains of Brucella abortus, Br. suis and Br. melitensis.

2. These strains could be classified in the brucella genus on the basis of cell morphology and staining, colonial morphology, cultural characteristics, biochemical properties, pathogenicity for laboratory animals and association with genital disease in the natural host.

3. The ovine strains have never been observed in other than the non-smooth phase. Consequently, these organisms lack the specific surface antigens of smooth brucellae but are antigenically closely related to the non-smooth variants of other brucella species. Three antigenic factors were identified and their presence confirmed in all twenty-seven ovine strains.

4. The N.Z. and Australian ovine strains appear sufficiently stable and distinguishable from other established groups of the brucella genus in a number of independently variable characters to justify their constituting either a new species, Brucella ovis, or a new variety, Brucella brucei var. ovis australasiae. The author wishes to thank Prof. W. I. B. Beveridge for his continued interest and for providing accommodation and facilities.