1. Previous work on the antigenic structure of the cholera group of vibrios is experimentally reviewed, and the data amplified and systematised.

2. The cholera group is defined as consisting of vibrios with similar biochemical characters and having a common heat-labile antigenic component.

3. The heat-stable antigens are divisible into:

(a) A considerable number of specific antigens, best demonstrated by O sera and H-O suspensions, which serve as a basis of classification into O subgroups.

(b) A non-specific component, demonstrable with O sera and O suspensions.

4. The first subgroup contains all the standard cholera vibrios from central laboratories, and the majority of other epidemic strains. We consider that it represents the only class of vibrios known for certain to cause epidemic cholera.

5. The races of this subgroup I are further divisible into two (or perhaps three) “types”, as established by Japanese workers, according to differences in their subsidiary O antigens.

6. The haemolytic “El Tor” vibrios are serologically diverse. The term “El Tor” should, as Shousha suggests, be reserved for those that have the same specific O component as the standard cholera vibrios.

7. For the identification of the undoubted cholera vibrios a standard subgroup I O serum is recommended in conjunction with the haemolytic test. The serum should contain both the main and the subsidiary antigens of the subgroup.

8. As a working rule it is suggested that bacteriological proof of “cholera” or a cholera carrier should rest on the isolation of a non-haemolytic vibrio with the specific O antigen of subgroup I.

The studies and observations on which this paper is based were conducted while one of us (K. V. V.) was holding a Fellowship of the International Health Division of the Rockefeller Foundation.

Our thanks are due to Mr P. Bruce White for constant help and advice, and to the numerous bacteriologists in various lands who have kindly supplied us with cultures and sera.

Mineral oils recovered from the peritoneal cavity of injected mice showed in all sixty-one instances, with the exception of liquid paraffin, a fall in the refractive index. This phenomenon is presumably due either to a chemical change (? oxidation or reduction) in the constituents of the oils brought about by the juices of the animal organism, or to a mechanical change resulting from the removal of selected constituents to other parts of the animal. This test will possibly prove to be superior to that of skin applications and estimation of the refractivity constants for measuring the amount of carcinogenic constituents in mineral lubricating oils and it has the advantage of necessitating the use of only one animal instead of 100. We are of opinion that our experiments may be of far-reaching importance. They carry us a definite step nearer to the understanding of the mechanism of cancer formation.

Mombasa is the main port for the East African coast, handling all exports and imports for the two territories, Kenya and Uganda, which are incidentally the worst plague centres in the area. A fair amount of the Tanganyika and Belgian Congo produce also reaches this port. As Mombasa is the receiving centre for all the export trade of Kenya and Uganda, it might be expected that plague, if conveyable in any form or by any means, would appear regularly with the arrival of some of the main crops which are usually considered to be associated with the disease in the interior. Maize and cotton are generally supposed to be connected with the incidence of plague, and it is of particular interest to contrast briefly the figures for the incidence of the disease at the port within recent years and the periods of export of these crops.

1. In view of the high carrier rate on discharge from hospital, the bacteriological examination of swabs from scarlet fever patients is of no value in the detection of probable infecting cases.

2. There is, however, a definite relationship between the degree of infection, as measured by the profusion of haemolytic streptococci in cultures on discharge, and the likelihood of the patient infecting others.

3. The causal connection between “infecting” case and return case is strongly supported by finding the same serological type of Streptococcus pyogenes in both cases.

4. A patient who has had complications in hospital is slightly more liable to become an infecting case than one whose course has been uncomplicated.

5. The commonest age group of infecting cases is 5–10 years.

6. The majority (70 per cent.) of the return cases occurred within 14 days of the arrival home of the infecting case.

7. Overcrowding in the home, and the number of the susceptibles exposed do not appear to be important factors in the production of return cases.

8. A history of tonsillectomy does not appear to bear any important relationship to the occurrence of infecting cases, but the inconclusive nature of our findings indicates the desirability of further investigation of this question and that of the relation of the condition of the tonsils to their infectivity.

9. Discharge from hospital as early as is consistent with a satisfactory clinical condition is shown to be advantageous from the point of view both of the patient and of the hospital administration.

10. The administration of scarlatinal antitoxin is likely to render a patient less liable to convey infection on discharge.

1. A mixture of anhydrous lanolin with about equal parts of olive oil was the most efficacious ointment tested for protecting our animals from mineral-oil dermatitis and cancer.

2. Some commercial products consisting of mixtures of the alcohols and esters contained in lanolin were, on the whole, less efficacious: possibly the apparent benefit was mostly due to the olive oil with which they were diluted.

3. Olive oil, glycerine, commercial soaps, etc., gave varying degrees of protection, the last being particularly useful under some circumstances.

4. In experiments with gas tars, lanolin does not appear to afford protection when relatively small quantities of it are mixed with the tar or when relatively large doses of tar are applied to the animal, before or after lanolin treatment.

5. Where the experimental conditions appear to conform more to those prevailing among most tar workers, lanolin has a definite protective action.

6. Separate application of the carcinogenic agent and the prophylactic agent as a rule results in a lower yield of tumours than applications of an admixture of the two. In this respect it is to be noted that, where the animals were treated with lanolin separately, the quantity applied was several times greater than that of the tar itself (similarly in mineral oil experiments). This, of course, was not the case in our experiments with the lanolin blends.

7. Relatively more lanolin is required to protect against gas-tar dermatitis and cancer than is required to protect against toxic oils or synthetic tars. This is probably due to the presence in gas tars of special inhibitory substances. Note the analogy in the action of small quantities of acid on mineral oils, the potency being raised, whereas larger quantities may lower it.

We recently described a new method for measuring the carcinogenicity of mineral oils, etc. (J. Hygiene, 35, 125). Further researches have provided a considerable amount of fresh data, which are briefly discussed in this paper. It may be recalled that the basic principle of the test depends upon the fall in the refractive index of an oil when injected into, and subsequently recovered from, the peritoneal cavity of the experimental animal. The standard procedure we have provisionally adopted is the injection of 0·5 c.c. of oil into a 20-g. male albino mouse, the oil being recovered after remaining 1 week in the animal. Up to the present we have performed about 800 tests with some 200 oils, half of which were ordinary commercial products. The general indications we have obtained are that the fall in the refractive index (K.I.F.) is proportional to the degree of unsaturation or dehydrogenation of an oil of given viscosity, the fall being a measure of the carcinogenicity plus dermaticity of the oil in question.

1. Psittacosis infection is enzootic amongst several of the common species of Australian parrots in the wild state. A large proportion of recently caught individuals of Psephotus haematonotus, Trichoglossus (two species) and Leptolophus hollandicus are infected. In other genera, demonstrable infection is rare, but enlarged non-infective spleens probably indicative of past infection are common.

2. The virus strains derived from wild Australian parrots appear to resemble closely those isolated from human and parrot infections in Europe and America.

The infectious fevers have, during the last fifty years, been the subject of much epidemiological research, and have thus been made to yield up secrets which have materially affected the whole outlook of preventive medicine. But there yet remains for exploration a vast adjacent territory, that of minor coccal infections of the skin. However, whereas the former, being clearly defined clinically and in many cases subject to compulsory notification, lend themselves well to investigations of this sort, Impetigo, as a type of minor coccal dermatitis, surrounds itself with dificulties. For not only does it vary very much in its appearances by the time it is first seen but it is often of so little severity that it does not come under the observation of a physician at all, so that the influence of missed cases, always an important factor to be reckoned with in the study of epidemics, may assume such proportions as to give quite an erroneous impression of the total incidence of the disease. Consequently the epidemic aspects of impetigo have as yet received very little attention.

1. The tuberculin reactions of 259 Hong Kong Chinese, mostly adults, were determined by the Mantoux method. Each individual was tested with various dilutions of both old tuberculin and tuberculo-protein.

2. Of 215 subjects above the age of twenty, 93·1 per cent, yielded positive reactions to old tuberculin in dilutions of 1/1000 or higher.

3. Tuberculo-protein compared with old tuberculin of similar dilutions did not yield such a high percentage of positive reactions, seldom produced such vigorous reactions and never caused vesiculation. (This may have been due to deterioration.)

Pp. 474–485. Messrs W. Martindale inform us that the Lactic Acid Pessaries reported upon by Dr John R. Baker in the Journal of Hygiene, Vol. 34, pp. 474–485, are not recommended by them as a contraceptive. They are made to the order of a clinic. (Editor.)

P. 528, line 26, for “glucose media, and did not affect saccharose and maltose media” read “glucose and maltose media, and did not affect saccharose media”

The investigation recorded in the present paper was undertaken as a corollary to the clinical trials with a new antityphoid serum, the results of which were recently published (Felix, 1935). Its object was to enquire into:

(i) the occurrence of Vi antigen in strains of B. typhosus freshly isolated from cases of typhoid fever;

(ii) the occurrence of Vi antibody in the blood serum of typhoid patients and convalescents.

1. Rough variants, derived from strains of B. typhosus which possess the Vi antigen, may still contain this antigen though the smooth O antigen has been lost.

2. Such variants, which are non-virulent, are yet capable of inducing active and passive immunity.

3. The virulence of B. typhosus depends on the combined activity of the smooth O and the Vi antigen. Nevertheless the Vi antibody alone is sufficient to protect against infection with strains of the highly virulent type.

4. The use of avirulent, rough, but Vi-containing variants as vaccines and in the preparation of therapeutic sera is discussed.

1. The survival of coliform organisms was studied in river water, either raw or sterilised, kept at different temperatures.

2. For determining the coliform count and the differential coli-aerogenes count in sterilised river water, direct plating of the water on agar, with subsequent study of a number of colonies picked at random, was used. For raw river water the rapid method described by Wilson and his colleagues (1935) was used, which obviates the necessity of plating and of colonial examination.

3. When Bact. coli and Bact. aerogenes were held in stored river water, which was protected from agitation, they underwent a gradual decrease in numbers and finally disappeared. At 37°C. they died out rapidly, but survived for a much longer time at temperatures in the neighbourhood of 0°C. They were able to survive longer in sterile water than in raw water.

4. Observations, however, made on water kept at room temperature and subjected to gentle aeration showed that not only did the organisms not die out, but that they actually multiplied, so that their numbers were considerably higher at the end of two months than at the beginning of the experiment.

5. In raw river water coliform bacilli survived longer at room temperature when kept in the dark than in daylight.

6. On the whole, aerogenes1 proved more resistant than Bact. coli to the environmental conditions provided. This was particularly noticeable in samples kept at room temperature (18°C.). In samples of raw water kept at 37°C. aerogenes proved slightly more resistant than coli, while at 0–2°C. the reverse was true.

7. The general conclusion seems to be that, except at very low temperatures, aerogenes is likely to survive longer in raw river water than Bact. coli.

8. This conclusion is clearly of importance in the interpretation of the coli-aerogenes results in water analysis.