This report is a contribution to the joint investigation, organised by the Ministry of Health, into the bacteriology of Scarlet Fever. It has been carried out with the aid of a grant from the Ministry to whom I am indebted for permission to publish these results.

The following summarises the findings elicited from the investigation, the significance we attach to the results and the conclusions we have drawn:

A careful study has been made of the reputed Wassermann reaction exhibited by theserum of certain normal animals with a view to throwing light on the nature of the reacting substance or principle in syphilitic serum.

The heated (55° C.) serum of various normal adult animals may fix complement along with the antigen used in the Wassermann test, e.g. rabbit, ox, sheep, horse, mouse, cat, dog, macacus, pig.

The complement-fixation reaction may be associated with the flocculation effect similar to that of syphilitic serum.

These reactions apparently represent a natural or normal property of the serum and do not appear to depend on any pathological condition.

Certain species, including man, are characterised by negative reactions, e.g. white rat, guinea-pig, frog.

The serum of the white rat in the unheated state, however, yields a definite but weakly positive flocculation reaction which is annulled on heating the serum to 55° C., showing that this species is not devoid of the particular principle. In some species there is great uniformity in the occurrence of both reactions (e.g. rabbit, ox, sheep, horse). Such uniformity has led us to regard the reaction as a natural one. In other species there is less regularity and both reactions in certain individuals may be quite negative. In certain animals there may be dissociation of the two reactions: the Wassermann reaction may be negative while the flocculation effect is positive (e.g. pig, pigeon, fowl, cat): the reverse may occur, the Wassermann reaction being positive, the flocculation test negative (e.g. dog, mouse, rabbit).

Certain positively reacting species are characterised by uniformly weak reactions, e.g. mouse.

The Wassermann reaction in normal animals is always limited in degree, contrasting in this respect with the very marked effects obtained with the serum from cases of active syphilis.

In species in which adult animals exhibit positive reactions, very young animals, e.g. up to 3–8 weeks of age, react negatively. The reacting power (observed in rabbits) is thereafter progressive in development and is parallel with the development of a natural antibody (anti-sheep haemolysin). This parallelism supports the view that these reactions are due to antibody-like principles in the serum.

No constant difference in thermostability of the reacting substances can be established between normal animal serum and the serum in syphilis. The degree of thermostability seems to vary slightly among individuals. The flocculating property is more stable than the complement-fixing principle both in animals and in syphilis.

These reactions in normal animals seem to be homologous with the corresponding reactions in syphilis. Our observations suggest that the syphilis serum reactions are due to antibody-like substances homologous with antibodies natural to certain species and widely distributed among animals.

The Wassermann and flocculation reactions in individual rabbits tested at intervals are relatively constant.

Marked augmentation of the Wassermann reaction has been produced experimentally in rabbits: (a) by immunisation with heterophile antigen, as originally shown by Taniguchi; (b) by experimental infection with B. tuberculosis. The effects of other non-specific agents have also been studied but marked alterations have not been observed.

Repeated subcutaneous injection of alcohol in rabbits abolishes the Wassermann property. The injection of certain other chemical substances also produces a weakening influence. Parallel effects are observed on the antisheep haemolysin.

An analytical study has been made of the Wassermann and flocculating substances in the serum of normal animals and human syphilitic serum. For this purpose carbon-dioxide fractioning of the serum has been used. The results have been recorded and differences have been elicited in the behaviour of the serum fractions between normal animals and human syphilitics. These differences probably depend on the total content of the reacting substances in the serum and their distribution in the serum fractions.

The carbonic-acid-insoluble fraction of normal human serum and the serum of negatively reacting animals even after heating at 55° C. may yield a weak complement-fixation effect with the Wassermann antigen. This property is “masked” in whole serum. It is lost on heating above 60° C. and is more marked in the unheated fraction.

The deviation effect produced by the unheated fraction is contributed to by an independent complement-deviation reaction with the alcohol present in the antigen suspension but is still manifest with alcohol-free antigen preparations, showing it is partly a true reaction with the lipoids proper. This effect of the carbonic-acid-insoluble fraction has not been paralleled in the flocculation test unless in certain exceptional instances.

These observations seem to indicate that the principle in serum responsible for the Wassermann reaction is present normally in minimal amount and in a masked state even in those animals which are negative reactors when tested in the usual way. It might be supposed, therefore, that the diagnostic reaction is due to the non-specific augmentation of this natural antibody-like substance.

The influence of various non-specific agents and different infective conditions on the content of the reacting substances in the serum of normal animals requires further investigation.

The complement-deviation reaction of fresh serum with diluted alcohol (substituted for antigen) has been studied in animals and man. The fact has been elicited that the heated carbonic-acid-insoluble fraction of the serum of animals (positive in the usual Wassermann test) and of syphilitic sera yields, along with diluted alcohol, a definite though weak complement-deviation reaction. This may also occur with heated whole serum. This effect is absent from heated normal human serum and the heated serum of “Wassermannnegative” animals. This reaction shows some analogy with the Wassermann reaction and the alcohol of the Wassermann antigen suspensions seems to be a contributory factor to the total complement-fixation in the Wassermann test. If heated serum is used, no fallacy is introduced in the diagnostic test even when the concentration of the alcohol is 1: 12.

The dissociation of the Wassermann and flocculating properties in syphilitic sera is evidenced as a result of carbon-dioxide fractioning—the soluble fraction being more active in the flocculation test, the insoluble moietybeing more active in the Wassermann test, though in some cases the dissociation is less obvious and may be quite absent.

It is suggested from the observations recorded that the Wassermann syphilis reaction represents an increase of a “lipoidophile” antibody naturally present in the serum in minimal amount and in a masked state, which in syphilis is non-specifically augmented in an analogous manner to the augmentation of the natural anti-sheep haemolysin by heterologous stimuli.

Comparatively few speciallised investigations of the physical development of school children seem to have been made in this country. The most comprehensive British investigation is that made by Arthur Greenwood. This enquiry, based on the published annual reports of the various Educational Authorities, as well as those that preceded it, did not touch the main problem of the present study; viz. the relation between physique and mentality. Miss E. M. Elderton, a year later, made a careful biometric study of the school populatin of Glasgow.

The inhalation of coal and stone dust, as used in collieries, by pit ponies produces no permanent lesions of the lungs.

The dusts accumulated in the lung continue to increase during the first two years of exposure (approximately), but the rate of elimination then becomes equal to that of absorption.

The dusts accumulate, probably in the lymphatics, firstly around the blood vessels, secondly around the bronchi, and thirdly in the deep layers of the pleura.

The dusts accumulate in greater amount around the smaller blood vessels and bronchi than around the larger ones.

There is a greater deposition of dust near the pleura than deeper in the lung substance.

The dust is eliminated via the bronchi and the lymphatics.

Dust accumulates in the lymph glands and spleen. In the former, at least, it is largely intracellular.

Excessive stone-dusting causes extra accumulation of dust within the lung: this, however, causes no fibrosis.

All forms of the soft pit stone used were equally harmless.

The normal horse's lung contains very little dust.

An epidemic of enteritis due to infection of milk with a Flexner type dysentery bacillus, causing over 1000 cases and 72 deaths, occurred in Aberdeen in 1919, and has previously been recorded in the Journal of Hygiene(1). Another mild-borne outbreak of enteritis, causing 110 cases and no deaths, occurred in 1923, and has similarly been recorded(2). The cause of this outbreak was not determined, but was assumed to be due to a living bacillus of unrecognised type. In July, 1925, there occurred a further extensive outbreak of enteritis, which has been proved to be due to infection of milk with Bacillus enteritidis Gaertner, and as the infection has been proved to be of bovine origin, the Gaertner bacillus having been isolated from the udder and flesh of the diseased cow, as well as from the infective milk, it appears advisable to record the out-break in considerable detail.

This paper is the result of an attempt to determine if, in the different social classes obtained by a grading of a large section of the male working population of England and Wales for the triennial period 1910–12, as described by the Registrar-General in the Supplement to his 75th Annual Report, there was shown any special susceptibility to cancer in particular parts of the body. From a comparison of the standardised mortality-rates from cancer in 16 different sites in (1) men of three social grades, namely, the upper and middle classes, skilled workmen and unskilled workmen, (2) two sub-groups of the upper and middle classes and (3) men of two social classes, a higher and a lower intermediate to classes 1 and 3 and 3 and 5 respectively, it seems reasonable to draw the following conclusions:

1. The mortality-rates from cancer in the majority of the parts of the body considered, including amongst others the tongue, oesophagus and stomach, which altogether account for 92 per cent, of the total deaths, are definitely higher in the men of lowest social status; the incidence decreases, though not always regularly, with ascent in the social scale.

2. The mortality from cancer in other parts of the body, namely, the bowel, the prostate and probably the pancreas, is definitely highest, however, in men of the best social status.

3. Though the relatively high cancer mortality-rates in these sites in the best social class may probably be attributed in some measure, which it is difficult or impossible to assess, to improved facilities for, and methods of diagnosis in this class, as compared with those in the lowest classes, this cannot be the whole explanation as the differences are considerable and as no increased mortality from cancer is evident in any of the sites except the pancreas with such an ascent in the social scale as takes place in passing from social group 1 b, to social group 1 a, where the influence of more skilful diagnosis might also be expected to reveal itself. If we may accept the mortality from hepatic cancer in the different social classes as an approximate index of the general accuracy of diagnosis of malignant disease therein, then varying accuracy of diagnosis can have little influence in producing the divergencies in mortality from cancer in these special sites that are found in the social groups under review.

4. The excessive mortality from cancer of the bowel amongst males of the best social class cannot reasonably be ascribed to their habits of life such as high-feeding and easy-living or to their alleged greater liability to autointoxication. If this were so, cancer of the stomach and cancer of the rectum might also be expected to show a higher incidence in the same social class; the mortality-rates from cancer in these sites, however, are not higher in this class than in the lower social classes.

General interest was first aroused regarding the respective powers of the human and bovine types of the tubercle bacillus to infect the human subject by the address of Koch at the Tuberculosis Congress in 1901. In this he stated that the two types produced different diseases, and that the amount of human tuberculosis due to infection by the bovine type of the tubercle bacillus was negligible.

(1) Mice can be readily infected with many strains of B. tuberculosis, both of human and bovine type, by intraperitoneal inoculation with a dose of 0·75 milligramme of moist culture. But, with a fairly virulent culture of bovine type, doses of 0·005 milligramme produced infections of almost the same duration as the larger doses.

(2) The investigation of seven cultures of human and six of bovine type showed that in general the animals infected with the bovine strains survived. for a shorter time than those infected with the human strains. Also, several human cultures failed to produce infection, whereas no failure occurred with the bovine cultures. But no constant difference was found between the duration of infections with the two types of bacilli. Thus rapidly fatal infections were produced by certain cultures of both types.

(3) The period of survival of infected animals depends partly on the particular culture used for inoculation, and partly on the individual resistance of the animal and, in the case of nearly full-grown mice, is independent of their weight at the time of inoculation.

(4) The effect of repeated passage of tuberculous material from mouse to mouse without interposing cultivation of the bacilli on artificial media was investigated with eight strains, the series of passages numbering from three to eight. Increase of virulence was repeatedly observed, but such increase was never maintained in subsequent passages. The evidence indicates that the individual host plays an important part in modifying the virulence of the organisms for other members of the same species.

(5) As regards maintenance of virulence, comparatively constant results were obtained with different subcultures of the same strain. But repeated tests over a period exceeding five years have given indications that the virulence of a strain may become altered spontaneously from time to time.

In a previous paper (Stewart, 1926), we have seen that the mutabile form of B. neapolitanus Emmerich is a heterozygote with a Mendelian formula IiFF, in. which F represents a unit character for the fermentation of a particular sugar, e.g. lactose, I represents a factor for the inhibition of F, and i represents the absence of I in a pair of allelomorphs. Similarly paracolon has a formula IIFF.

The following paper gives some results of a series of experiments on the bactericidal power of various sources of ultra-violet radiation. The “power” of the source was in each case measured by the quartz-cadmium photo-electric cell described by the authors (1925), and it is shown that very definite and practically useful correlations exist between the cell reading and this typical abiotic action.

In the Medical Research Council's Special Reports, Nos. 91 and 92, and in the Journal of Hygiene, vol. XIV. No. 1, July, 1925, W. G. Savage and P. Bruce White stress the desirability of restricting the term “B. paratyphosus B” to the organism of paratyphoid fever and nothing else, and of designating the organism that most commonly causes food-poisoning outbreaks as B. aertrycke, and not as B. paratyphosus B (type aertrycke). In view of the fact that the features of a paratyphoid fever outbreak due to infected ice-cream, and of an aertrycke enteritis due to infected pork as occurring in Aberdeen in 1925 emphasise the distinction between paratyphoid fever and aertrycke enteritis, it has seemed well to record these two outbreaks in some detail for the purpose of contrasting them the one with the other and with the milkborne Gaertner enteritis which is recorded in the preceding paper.

The problem which we shall discuss in this communication is of great importance, is perhaps the most important of all epidemiological problems, and we are far indeed from supposing that we have solved it. We think, however, that the work we have done is certainly useful in enabling us, and others, to state the problem correctly, and possibly useful in suggesting a first approximation to its solution.

1. In the absence of the epidemic prevalence of the dysenteries over a period of 30 months it is found that cases of the various forms of dysentery as occurring in Aberdeen have been in the proportion of 1 amoebic, to 3 Flexner, to 6 Sonne dysenteries, and it is concluded that B. dysenteriae Sonne is the most frequent cause of dysenteric outbreaks in Aberdeen in non-epidemic times.

2. A description of the clinical and bacteriological features of Sonne dysentery is submitted.

3. Preliminary experiments, undertaken with a view to ascertaining whether B. dysenteriae Sonne produces a true exo-toxin, are described.

The foregoing report of Professor van Loghem and his co-worker, Miss Benjamins, confirms the results found by Professor Beattie and Dr Lewis, concerning the bactericidal action in milk of the electric current of high voltage. It also proves that the sterilising power of electrical treatment with carbon electrodes is not inferior to that with copper electrodes. These results, and also my experience of the vitamin C sparing effect of the carbon electrodes, have caused me to recommend the use of this kind of electrode in the electric treatment of milk, provided that the milk used be fresh and that it contains but little oxygen. The same reservation applies to milk pasteurised by heat and to pure raw certified milk. It is important that the supply should be fresh.