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.

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.

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.

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.

Coliforms were readily obtained from many soils. In samples taken from sites exposed to animal contamination Bact. coli type I occurred predominantly. A large number of samples taken from grassy banks, only remotely exposed to contamination, were found to contain intermediates. It was found that the greater the probable degree of contamination of the soil the higher was the proportion of Bact. coli type I, and that the less the probable degree of contamination the higher was the proportion of intermediates. It is difficult to explain this merely on the basis of the prolonged survival of intermediates in soil, and it would appear obvious that the source of these intermediates lay elsewhere than in animal faeces. The numbers in which they were found in soil, however, were not of the order expected of bacteria living in their natural environment, and consequently it was equally difficult to conclude that these intermediates were actively established in soil.

1. The clinical findings and environmental factors of 138 families infected with Microsporum canis are recorded.

2. Of the 171 children suffering from tinea capitis, 25% had lesions which remained localized, 51% had local spread of infection and 24% had a generalized spread, involving most of the scalp.

3. The clinical pattern of the infection was not associated with the sex or age of the child, nor with the source of infection.

4. In 30.5% of the families there was a definite cat source of infection, in 3.6% a definite dog source and in 13.9% a definite human source. A further 20.3% had a probable animal source, and 7.9% a probable human source, while in 23.9% no obvious source of infection could be found.

5. The social status of 95 families was investigated. In 4.2% the breadwinner was a farmer, in 12.6% he belonged to the professional and managerial group, in 60% he was a skilled labourer and in 22.1% an unskilled labourer. The houses of 75 families were visited. House conditions were classed as good in 58%, fair in 33% and poor in 9%. It is suggested that ringworm due to M. canis in New Zealand is not associated with poverty or poor conditions and no stigma should be attached to the development of an infection.

6. Evidence for the following types of transmission of infection was obtained: cat to child; dog to child; child to child; child to adult; cat to cat; child to cat; dog to cat; cat to dog.

7. The findings of the investigation are discussed. It is suggested that human infections with M. canis are part of a complicated network resulting from the commensal relationship of the cat to man. Better care of cats so that kittens are not allowed to stray would assist in the control of human infections.

Gordon & Turner (1955) reported that glucose and other sugars intensify the protective action of glycine against the heat-inactivation of complement, so that in their presence the concentration of glycine required to protect complement against inactivation at 55° C. is greatly reduced. Moreover, when high concentrations of glycine (e.g. 10%) were used, higher temperatures were required to inactivate complement if the glycine was dissolved in a high concentration of a sugar. They also showed that although this intensification is a property of a wide range of sugars, it is not shown by the corresponding alcohols, although inositol is exceptional in causing marked intensification. No explanation was offered for these findings and further experiments have been undertaken to throw light on them.

Sections of chorio-allantoic membranes fixed at intervals after infection with large doses of vaccinia virus showed almost homogeneous areas appearing in the cytoplasm after 4 hr.; these areas contained immature forms of virus which had a thin surface membrane and an eccentric ‘nucleoid’, and were surrounded by mitochondria. Mature forms of virus, having a larger central nucleus-like structure and a thicker cortex, were first found in areas of virus growth 10 hr. after inoculation. Similar immature and mature forms were found in cells infected with fowl-pox, myxomatosis and ectromelia viruses. It is concluded that the immature forms are of low infectivity or not infective.

Variation in host susceptibility results in flattening of the quantal response curve obtained in dilution counting experiments. This departure from the exponential curve obtained with uniform hosts is found primarily at the lower dilutions, where the infection rates are high. The test proposed by Moran, for the detection of host variability, may easily fail to detect quite appreciable heterogeneity with the numbers of observations that are likely to be available in practice. Examination of the response curves corresponding to various theoretical distributions of susceptibility suggests that detection of heterogeneity is unlikely unless the probability that a particle can initiate infection is distributed with a low mean and considerable positive skewness.

The problem is related to that of estimating the standard deviation of a tolerance distribution from quantal response data. This suggests an alternative test, based on the Spearman-Kärber method, which, however, appears to be no better than Moran's test. Both methods provide estimates of the variability of the susceptibility distribution.

The intramuscular injection of large amounts, 2–3 g., of Trichomonas foetus crude antigen into five young calves during the first 3 weeks of life produced no antibody.

When the animals were tested with the standard challenge at intervals of several months they responded feebly, showing a definitely impaired capacity to produce antibody, when compared with the response of normal animals.

The ages of the animals still showing this partial paralysis ranged from 1 year and 5 months to 2 years and 2 months.

1. A good immunity was produced in chickens against oral infection with Salm. gallinarum by the use of either of two live attenuated vaccines, one smooth, 9S and one rough, 9R. Dead vaccines had little or no effect.

2. The immunity possessed by chickens vaccinated with 9R at 7 weeks of age commenced to wane 12 weeks later. Chickens similarly vaccinated with 9S were completely immune 4, 12 and 34 weeks later. When tested during the active laying period (at 20 weeks after vaccination) their immunity, although substantial, was not complete.

3. Vaccine 9R did not produce demonstrable agglutinins against smooth Salm. gallinarum in chickens. It was non-lethal to 1-day-old chicks and was never found to revert to the smooth virulent form in vitro or in vivo. By contrast, vaccine 9S produced agglutinins and was lethal for 1-day-old chicks, its virulence not being increased by passage. No deaths were ever observed when this vaccine was used in either chickens of 5–12 weeks old or laying hens.

4. Although both vaccines produced a good immunity when employed in laying hens, vaccination with 9S was accompanied by a marked reduction in egg production; this was not the case with 9R.

5. An immunity of the interference type was also evoked by both live vaccines. This immunity was still produced to some extent in chickens injected with 9S, 2 days after they were infected with Salm. gallinarum by mouth.

6. The interference effect could not be produced by the use of either dead Salm. gallinarum vaccines or certain non-specific substances. The intravenous injection of indian ink had a marked adverse effect on the course of the disease. Injecting chickens with a virulent strain of Bacterium coli at the same time as they were infected with Salm. gallinarum resulted in the latter infection running a milder course than would normally have been expected.

1. The immunity to Salm. gallinarum infection produced by injecting chickens with live cultures of different species of Salmonella and other bacteria has been studied.

2. Salm. pullorum produced a complete immunity equal to that produced by Salm. gallinarum itself. The immunity evoked by 11 of 12 other Salmonella species belonging to group D, although substantial, was less complete. Three of four rough group D strains and an avirulent strain of B. coli produced no immunity. Although a considerable degree of immunity was produced by the fourth rough strain it was not equal to that produced by rough strains of Salm. gallinarum.

3. Owing to their lethal nature, it was not possible to be definite about the extent of the immunity produced by two group B strains, Salm. typhi-murium and Salm. Chester, although it may have been equal to that produced by the group D strains.

4. A slight but definite degree of immunity was produced by two group C and two group E Salmonella cultures. Since this immunity was no better than that possessed by chickens previously infected with either Pasteurella septica or Staphylococcus aureus, it was considered to be non-specific in character.