1. A group of rats has been fed on a poor human dietary supplemented with milk and green food. A further group has been given the same dietary supplemented with Ca and P as salts, equivalent in amount to that present in the milk and green food. The experiment has been continued over three generations.

2. The diet supplemented with Ca and P salts has been found to be as effective as that containing milk and green food in promoting reproduction, calcification and tooth formation; it has induced growth as effectively in the first generation of rats but is unable to maintain this growth rate as effectively over several generations. It is obvious that Ca and P are of the chief deficiencies in the poor diet. The addition of these elements greatly increases the nutritive value of this diet, but they are inferior in this respect to milk and green food supplements.

3. Under conditions of Ca and P lack, tooth formation is much less adversely affected than is skeletal ossification.

In a recent report (Greenwood et al. 1936) we included a short discussion of the few scattered observations that we had made on the effects of the dispersal of an infected herd (pp. 189–92). Briefly, we had found that the division of a herd, in which an epidemic due to Bact. typhi-murium was under way, into small isolated groups was followed by a greatly decreased rate of mortality in those groups when the dispersal was carried out at the beginning of the beginning of the epidemic period. Reaggregation of the groups resulted in a fresh spread of the disease, but the final mortality was lower than in a similar herd which had not been dispersed during the earlier stages of cage life (Topley, 1922). In a subsequent experiment (Topley & Wilson, 1925) dispersal was carried out at a later stage of epidemic spread, and very different results were obtained. For the first three weeks or so after division into small groups there was no material difference between the mortality experienced by the dispersed and not-dispersed mice. But at about the 25th day the death-rate in each of the dispersed herds showed a definite decline, while that in the undispersed herds continued unabated for some further length of time.

1. Silver nitrate or sodium merthiolate can be used for the sterilization of suspensions of B. typhosus and neither have any immediate destructive effect on the Vi, O or H antigens.

2. Two methods of employing silver nitrate as a sterilizing agent are described.

3. Physiological saline solution with silver nitrate added is bactericidal for B. typhosus and the staphylococcus but has no inhibitory action on the growth of moulds.

4. Vaccines sterilized and preserved with silver nitrate after storage for 6 months at 7° C. were found to have retained their Vi antibody stimulating properties.

5. A vaccine sterilized and preserved with “katadyn” after storage for 18 months at 7° C. still contained some Vi antigen and was superior as an immunogenic agent to a freshly prepared heat-killed-phenolized vaccine.

6. It would appear that the stability of Vi antigen is increased by the addition of silver within certain limits, but this effect is only obtained if low temperature storage conditions are maintained.

7. A vaccine sterilized and preserved with sodium merthiolate after 6 months' storage at 7°C. failed to stimulate any Vi antibody in the rabbit.

1. The paper records, for the first time, the isolation of Bact. paratyphosum C in Egypt.

2. It has been isolated from the urine of nine patients and the faeces of two patients suffering from enteric fever during the summer of 1937 and the early part of the present year.

3. Its frequency is comparable with that of Bact. paratyphosum A, and may exceed that of Bact. paratyphosum B.

4. Its inclusion in prophylactic vaccines, along with the usual “T.A.B”. vaccine is worthy of serious consideration.

An account is given of outbreaks of anthrax among mink, which occurred in Great Britain during 1936–8, and the possible danger to human beings from this source is discussed. Attention is called to the peculiar features of one of the outbreaks and to the probable mode of infection.

Acknowledgements. My best thanks are due to Dr D. Jordan Lloyd for supplying information and references concerning the dressing of pelts, to the Veterinary Department of the Ministry of Agriculture for details of outbreaks of anthrax during 1936–8, and to Dr F. C. Minett for his assistance in compiling this paper.

All the four types of acid-fast bacilli used in this investigation have proved virulent for the golden hamster. Of the four types the bovine is the most virulent for the species and, after subcutaneous inoculation, gives rise to severe generalized progressive tuberculosis, the lesions containing enormous numbers of tubercle bacilli. The human type is also highly virulent for the hamster and produces general progressive tuberculosis closely resembling that set up by bovine bacilli. Caseation of the lesions in the organs was, however, less extensive in the human than in the bovine infections but there was little difference in this respect between the glandular lesions of the two infections, and multiplication of bacilli was as profuse in one as in the other. Avian bacilli can readily multiply in the tissues of the hamster and cause death, but appear unable to give rise to macroscopic tuberculous lesions. Only one hamster was injected with avian bacilli and the result of this experiment is not in accord with those of Balfour-Jones already quoted. The vole bacillus is less virulent for the hamster than either the bovine or the human type of bacillus. Of the two hamsters injected with this type of bacillus one was killed 152 days later, its general condition then being good and its body showing plenty of subcutaneous fat. Nevertheless the organs were found to contain tuberculosis-like lesions, numerous in the spleen and liver, and the lymphatic glands generally were enlarged. The remaining hamster died 188 days after inoculation and showed generalized disease very similar to that in the last hamster. The glandular and visceral lesions of both hamsters contained very numerous acid-fast bacilli but, in striking contrast to those produced by bovine and human bacilli, showed no evidence of caseation.

Acid-fast bacilli were present in the faeces of all the hamsters; they were numerous in those of hamsters 3, 4, 5 and 2 and relatively sparse in those of hamsters 1 and 6.

1. A range of commercial distillates of a topped crude Borneo, mineral oil were tested for carcinogenic activity and it was found that the peak was around a viscosity at 25° C. of 200 to 250 Centipoises.

2. The whole range of oils was biologically active. This activity had been foreseen from an examination of the physical characteristics, alone sufficient to condemn the utilization of any single representative as a lubricant when likely to come into contact with the user.

3. A greater concentration of the carcinogenic material was obtained by molecular distillation of oils than by ordinary distillation at from 3 to 10 mm.

4. The middle fractions of a Borneo crude oil were mostly responsible for pathological changes in the organs—fatty infiltration of the liver and hyaline degeneration of the spleen. These results again confirm previous findings.

5. Lung tumours were, according to our experience with mineral oils more prevalent than is usual when utilizing this type of agent for testing carcinogenicity for the skin. Their incidence was somewhat higher in the more viscous fractions but was not apparently related to their carcinogenicity for the skin.

In conclusion we should like to thank Dr C. C. Twort, former Director of this Department and now of the Portslade Laboratories, Sussex, for his helpful suggestions and advice in the compilation of this paper, and wish also to acknowledge their indebtedness to Dr J. R. Bowman of the Mellon Institute of Industrial Research, University of Pittsburgh, for a micro method of viscosity determination.

Antisera prepared in the rabbit by injection of crystalline horse-serum albumin or crystalline human-serum albumin show a considerable diminution in specificity after more than one course of six to eight injections has been given.

The ratio of precipitate nitrogen to antigen nitrogen at the optimal point is smaller in antisera obtained after one course of injections than in antisera derived from subsequent bleedings.

In the case of antisera obtained from first bleedings, the ratio of precipitate nitrogen to antigen nitrogen determined at the optimal point with homologous antigen is of approximately the same value in both the antigen-antibody systems studied. The increase in the values of the ratios for antisera from subsequent bleedings is also the same for both systems.

The purpose of the investigation was to examine the reason for the relative age shift in the incidence of diphtheria. The disease has been represented as now concentrating on children of school ages. We analysed, for various quinquennial periods beginning with 1901–5, the statistics of the notifications and deaths according to age and sex in the London boroughs which we classified into four social classes where I to IV represented descending order in the social scale. The conclusions arrived at were:

I. The age shift as represented by the ratio of the mortality at ages 0–4 to ages 5–9 years which has taken place in London has been found to occur mainly in the poorer districts. The ratio in the residential districts has not altered appreciably during the thirty years under review (Table V).

II. The age shift is also indicated by the morbidity statistics for the three quinquennial periods, 1901–5, 1909–13 and 1919–23, as there was a significant increase in the mean age of attack of children under 15 years of age.

The case rate at ages 5–14 during 1929–33 as compared with that in 1901–5 has increased most amongst children in the lowest social group.

III. Each of the variables (a) the decrease in the birth-rate between 1911 and 1931 in each London borough—an index of the change in the size of family—and (b) the decrease in infant mortality—a measurement of environmental improvement—is positively and significantly correlated with (c) the corresponding change in the size of the ratio of the case rates at ages 0–4 to 5–9 years. The coefficients were:

but the partial correlation coefficients

indicate that the change in the size of family is the more important factor as the value of rac.b is fairly large and significant, whereas the correlation between the change in the ratio and the environmental improvement when the effects of the decreasing birth-rate are made constant—rbc.a—becomes statistically unimportant.

The process of physical growth in children is manifested by changes in their size, mass and shape. Changes in size are ascertained by measurement, usually, of the standing height of the child, but occasionally of the sitting height, and sometimes, also, of the chest circumference and the width between the hips. Changes in mass are detected by weighing, whilst changes in shape, which are due to unequal rates of growth in height and in mass, are estimated by methods referred to later.