In December, 1920, Capt. F.C. Minett, R.A.V.C., of the Royal Army Veterinary School, Aldershot, published an account of diphtheria bacilli isolated by him from eleven horses and one mule. He states that during the last year of the War and for some months after the Armistice the laboratory at the Army Veterinary School received for examination numerous specimens of pus derived chiefly from suspected cases of ulcerative lymphangitis; a condition in horses in which swelling of the lower parts of a limb or limbs is accompanied by abscess formation followed by ulceration. From this material he collected and investigated a number of diphtheroid strains including the bacillus of Preisz-Nocard and in the course of his inquiry discovered twelve strains of the diphtheria bacillus.

While investigating variations in agglutinability, occurring among certain strains of paratyphoid bacilli, it became desirable to obtain cultures derived from single bacterial cells. The technique at first adopted was that devised by Mutch (1919), but the results obtained were not satisfactory. Certain modifications of this method were attempted, but were no more successful.

The main difficulty, and one which appears to us to have been far too little emphasised in all the methods hitherto described, has been encountered in obtaining satisfactory conditions for the microscopical observation of the bacillary suspensions employed. The difficulty of accurately observing hanging-drop preparations, and still more of controlling manipulation of them by microscopical observation, would seem to us to have been insufficiently realised; and the ease with which faulty interpretation of microscopical appearances may introduce fatal errors into work of this kind has not, perhaps, been fully taken into account.

This subject has been dealt with by so many investigators and, within recent years in the United States, in such minute detail that it would seem surprising that no definite conclusion has yet been reached as to the cause of the disease or the actual part played by the diet in bringing about the condition.

1. Morphologically B. abortus and B. melitensis are identical. The “coccoid” form is not a constant feature and a more satisfactory generic name would be “Brucella.”

2. The organisms cannot be differentiated by cultural, bio-chemical, or staining methods, or by the agglutination reaction.

3. From absorption experiments, it would appear that B. melitensis is a sub-strain of B. abortus.

4. Dose for dose B. abortus is much less virulent for the guinea-pig than B. melitensis, approximately about 1: 6.

5. Immunisation of monkeys (one experiment only) with killed suspensions of B. abortus protected against subsequent infection with B. melitensis.

In conclusion I wish to thank Professor Ledingham for much valuable advice throughout the investigation, and Dr R. St John Brooks for supplying me with cultures from the National Collection.

In a previous communication (1921) experiments have been described showing the effect produced by continuously adding normal mice to a cage, the population of which is infected with bacilli of the group which includes B. gaertner and B. suipestifer. It was seen that under these circumstances the spread of infection progresses in a series of epidemic waves, and that the survival-time of any batch of mice varies according to the period at which they are introduced to the cage. It was further shown that, if such regular and continuous addition of susceptible animals be persisted in over long periods of time, all the micewill eventually succumb, while, if the addition of new individuals be discontinued, the epidemic will eventually subside, leaving a proportion of survivors who may remain in apparently good health over a considerable period.

In a series of investigations on the epidemic spread of bacterial infection among mice (Topley, 1919, 1921), it has repeatedly been noted that, if an epidemic be started among a mouse-population by feeding certain animals on cultures of B. gaertner and subsequently introducing other susceptible mice into the cage, a varying proportion of these latter may succumb to infection with an organism morphologically and culturally identical with B. gaertner, but differing sharply from it in regard to its agglutination reactions. This organism has been referred to in previous communications as belonging to the B. suipestifer group, using that term to include B. aertrycke and other closely related types.

1. Amoung a large number of strains belonging to the various absorption types of the paratyphoid B group and kept under observation in laboratory culture over a number of years, constancy of type has been demonstrated.

2. Only two alterations in the serological nature of certain cultures have been noted; they were due (a) to the development of so-called “rough” variants, (b) to the degeneration of strains into antigenically less effective “substrains.”

Though both are variations within the limits of the absorption type, the serological character of the affected strains may be so obscured that a greater variation than has actually taken place may be ascribed to them, unless the precautions indicated are observed.

3. When “rough” strains are in question, agglutination results are to be mistrusted, for a marked cosmopolitanism in respect of this test has been seen to exist among such alien species as B. enteritidis Gärtner, B. paratyphosus A and B. paratyphosus B.

Professor L. S. Dudgeon, when consulting bacteriologist to the Forces in the Balkans during the late war, had tried the effect of drying the stools of suspected dysentery patients on some porous material so as to leave only the mucus. In bacillary cases he found that a more abundant growth of dysentery bacilli was obtained from the dried mucus than from the untreated specimen, so that the drying had no harmful effect on the organisms. He used for this purpose unglazed red tiles such as were to be found locally, and suggested that the method should be given a more thorough trial with a more satisfactory type of tile made in this country. With this view the following experiments were made.

In a previous communication one of us showed that certain strains of B.typhosus presented marked serological differences. The experiments, to which we now propose to make further reference, were conducted in the following manner.

In nearly every case where canned meat or fish is condemned as unfit for human consumption, the action is based upon the physical features of the unopened tin, which are held to indicate decomposition of the contents. No studies of canned foods would therefore be complete without some detailed consideration as to the real harmfulness of such rejected foodstuffs.

In order to obtain knowledge of the fate of tuberculin in the organism the substance was injected into normal animals. After injection, tuberculin rapidly disappears from the vascular system and does not reappear in the urine till after several hours. In the meantime the substance is bound in the organism, probably in the bones and in the liver. Living cells in vitro also have the faculty of binding tuberculin.

Through numerous experiments a difference is demonstrated between the complements of different sera, a fact which strongly supports the theory of the plurality of complements. Evidence is brought forth which points to a difference between tuberculous and non-tuberculous complement.

Tuberculin is highly noxious to the vitality of the white blood corpuscles, and more toxic to corpuscles from tuberculouos organisms than from not-tuberculous organisms. A certain protective power in regard to the toxic action of tuberculin is found in the serum. This power is greater in serum from normal organisms, than in serum from tuberculous organisms.

By means of vital staning a difference is demonstrated between the effects of tuberculin upon the leycocytes from normal and tuberculous animals.

There seems to be considerable evidence in favour of the view that the immediate cause of this acute infective fever is an organism in the form of a streptococcus although there does not yet appear to be unanimity as to the specific characteristics of the latter. With regard to the secondary or indirect or predisposing causes of the complaint, the agencies which influence favourably the development and activity of the organism and consequently the prevalence of the disease, there has been a definite tendency in recent years not only to abandon the hitherto prevailing opinion on the influence of certain meteorological factors, namely, that increase in the amount of rainfall and decrease in the temperature are generally associated with increased incidence of the disease but even to assert that the action of these factors is the reverse of this.

(1) Our experiments support the view that influenza is casued by B. influenzae, and that pneumococci and certain streptococci are the most important agents of secondary infections. No new type of bacterium was discovered, and no evidence was obtained of the presence of an ultra-micrascopic virus.

(2) B. influenzae appears more toxic for rabbits and mice when grown on fresh liver or kidney media than when grown on blood agar or in blood broth, and this is especially so when the kidney or liver is obtained from an animal of t he same species that has previously been inoculated with a culture of the influenza bacillus.

(3) Three fairly distinct special forms have been isolated from cultures of B. dysenteriae. They are probably not sexual units or stages in a true life cycle. Special large forms have also been obtained from cultures of B. influenzae, but these reverted back to the normal small type after several sub-cultures.

(4) A filter-passing material has been found associated with certain micro- cocci from vaccinia and in pure cultures of members of the dysentery-typhoid- coli group of bacteria. This material breaks down and dissolves the bacteria of the cultures, and the “infection” can be carried to fresh normal cultures. The evidence is against its being a living ultra-microscopic virus infecting the bacteria, but it may have some connection with the special forms. No definite evidence of a similar dissolving material has been found associated with cultures of the influenza bacillus.

(5) There is some indication that one or more of the forms isolated from pure cultures of dysentery bacilli may be special toxin-producing units, also that this function is at its maximum when the bacilli are first produced by the normal small forms or by sexual units of a normal culture. This may possibly be the case also with special forms that have been found in cultures of the influenza bacillus.

(6) It is believed that non-pathogenic wild varieties of ultra-microscopic viruses must exist in nature, and that they should present less difficulty in cultivation than the pathogenic varieties. Cultivations were made from filtrates of soil, faeces and water on various special media, and the tubes incubated in various gases. The chief gases tested either alone or mixed were oxygen, nitrogen, carbon dioxide and sulphuretted hydrogen. All the results were negative, but some interesting deposit colonies were obtained on media con taining a small quantity of sodium sulphide.

(7) The influenza bacillus grows in symbiosis with amoebae on blood agar, and in such cultures the bacillus lives considerably longer.

(8) The influenza bacillus grows in symbiosis with a small spirillum that was isolated from a grass emulsion, and in symbiosis with an extremely minute and delicate bacterium isolated from garden soil; after passing the emulsions through a Berkefeld filter. With these delicate bacteria the influenza bacillus will grow on media containing no blood, and if an egg medium is used the mixed growth is dense, heaped up and brownish in colour. In such cultures the in fluenza bacillus may live for months.

(9) The influenza and other bacilli will grow in an atmosphere of pure oxygen or pure carbon dioxide under diminished pressure.

In a previous communication (Wordley, 1921) I fully described a method, introduced by Dudgeon, for isolating organisms from faeces and sputum. The material is dried to a powder and this dried powder spread over convenient culture media. From my observations this method, for faeces, was found to be superior to those generally in use for isolating the dysentery and enterica group of organisms.

The following paper contains a study of the results of bacteriological examinations of samples of Grade “A” (Certified) milk, some of which were 24 hours old and others 30 hours old at the time of examination. This work was started in 1916 and is still being carried on. Some of the results have already been published. For purposes of comparison, these results, together with further series, are included in the present paper.

1. The organism of Trench Fever is present in the “whole blood.”

2. The evidence seems to be in favour of the organism being an extra-corpuscular rather than an intra-corpuscular parasite.

3. The smallest quantity of whole blood which has given rise to the disease was 0.5 c.c.

4. The blood is infective from the first day of the disease, and in one case was found to be still infective after 443 days.

5. The microscopical examination of the blood has not up to the present revealed the organism or at least has not differentiated it from other granules present in blood.

6. There is some evidence that the organism may leave the body in the sputum and urine, but the chief and only way which has any practical significance is by means of a blood-sucking insect, the louse.

7. There is no evidence that infection takes place through food, drink or air, but only by inoculation of the organism by means of this insect.

8. The chief method of infection is not, as might be expected, by the bite of the louse, but by the infected excreta of the louse being brought in contact with an abraded surface of the skin.

9. After a louse has fed on a case of Trench Fever, five to nine days elapse before the excreta become infective.

10. If lice are fed on a case for some time a high percentage of the lice become infective.

11. There is no transmission of the organism of Trench Fever from infected lice through the egg to their offspring.

12. The tenth of a milligram of excreta has been found sufficient to set up the disease.

13. The organism of Trench Fever retains its virulence in louse excreta for at least four months.

14. The virulence of lice excreta is lost by exposure to dry heat of 100°C. for 20 minutes; to moist heat of 60°C. for a similar time.

15. It is doubtful if any of the laboratory animals are susceptible to Trench Fever.

16. It would appear that most men are susceptible to the disease, only a very few individuals having been found apparently naturally immune.

17. One attack seems to produce only a partial and limited immunity.

18. In regard to the etiology of Trench Fever there is strong evidence that the Rickettsia-like bodies found in infected louse excreta are the micro organisms of the disease, but as they have never been cultivated outside the body the final proof is still wanting.

19. The organism cannot be said to be a filter-passer; the evidence would seem to be more in favour of its being a small body such as the so-called Rickettsia.

The work contained in the following paper demonstrates that valuable evidence of the relative incidence of bovine and human tuberculosis may probably be obtained by a careful record of the chances of contact infection in each case.

The material dealt with was derived from a central clinic in a large industrial Country Borough(Newport, Mon.) and from a series of smaller clinics. Two of the latter were in industrial (coal and iron) districts and three in small country towns containing semi-urban and rural populations.

In 1885, the Dutch vital statistician, Prof. Van Pesch1 drew attention to a peculiarity of the curve of death rates at ages which he first noticed in the Netherlands’ statistics of 1870–79 and subsequently again found in the three following decades.

1. That there is reason to believe that sporadic cases of cerebro-spinal fever occurred in Hong Kong previous to the outbreak of the epidemic in 1918.

2. That the epidemic followed a widespread infection of influenza colds.

3. That the mortality out of a total of 1040 cases was 85–48 per cent.

4. That the most susceptible age was found to be the age period under five years.

The younger the individual, the greater the susceptibility, with the added proviso that the extremes of life suffered most.

5. That once the epidemic was established, a drop in the temperature, steadily maintained, accompanied by an increase in the saturation of the air as regards moisture, associated with a lack of sunshine, was found to be followed after a lag of a few days, by a rise in the number of cases. This lag showed a tendency to increase as the epidemic progressed, from three to four days at the beginning to six to seven days at the end of the epidemic.

6. That the number of cases in any given area varied directly with the overcrowding in that area, and this bears out the contention that overcrowding is one of the most important features in the epidemiology of cerebro-spinal fever.

7. That the housing conditions in Hong Kong are such as to necessitate immediate action on the part of the Government, to safeguard the public health of the colony.

8. That new entries to Hong Kong formed a large proportion of the cases, and that this appears to be an important factor in the epidemiology of the disease.

9. That the poorest, most hard worked and badly housed portion of the community suffered most in the epidemic.

10. That the recognition and isolation of carriers is impracticable in an epidemic of any considerable dimensions.

11. That in the present condition of the knowledge of the means by which infection is spread, the wearing of a screen composed of some impervious material such as celluloid would seem to afford complete protection to the wearer against droplet infection.

12. That known carriers should be compelled to wear this screen until such time as they are proved free from the meningococcus. Thus protected, the carrier could pursue his usual avocation and the community be safeguarded from infection at a minimum of expense.