It is generally accepted that the infection of many diseases is conveyed by the discharge of droplets containing the biological materies morbi in the acts of coughing, speaking, etc. In some cases, for instance that of measles, it is believed that if a person harbouring the materies morbi has the opportunity of projecting it upon the upper respiratory tracts of non-immunes, a considerable proportion of the latter will develop the clinical disease. In other cases, for instance cerebro-spinal fever or acute poliomyelitis, it is believed that although, in consequence of the activity of the primary source of infection, many other persons will acquire and harbour the materies morbi only a small proportion of them will develop the disease.

When a disease assumes epidemic proportions, it is now generally recognised that certain conditions govern the rise and fall of the epidemic wave. Farr was probably the first person to attempt to describe these conditions in quantitative terms. His theory was “ the real law (i.e. of the epidemic) implies that the ratio of increase goes on rapidly decreasing until the ratio itself is decreasing.” In the Appendix to the second Annual Report of the Registrar-General he discusses the progress of the smallpox epidemic which had spread through England and Wales in 1837–9, causing the deaths of over 30,000 persons. “Five die weekly of smallpox in the metropolis when the disease is not epidemic… Why do the five deaths become 10, 15, 20, 31, 58, 88 weekly and then progressively fall through the same measured steps?” He suggests, “amidst the apparent irregularities of the epidemic of smallpox and its eruptions all over the kingdom, it was governed in its progress by certain general laws.” He found that the deaths from smallpox in the quarters of the year during the epidemic increased up to the third quarter very nearly at the ratio of 30 per cent. “The rate of increase is retarded at the end of the third period, and only rises 6 per cent. in the next, where it remains stationary, like a projectile at the summit of the curve which it is destined to describe. The decline of the epidemic was less rapid than its rise.” He showed that the fall of mortality took place at a uniformly accelerated rate and calculated a “regular series of numbers” (such that the second differences of the logarithms are constant) for the decline of the epidemic.

About one-fourth of the cases in a series of 160 patients suffering from scarlet fever appeared to be Dick-negative in the acute stage of the disease.

Throughout the illness there was a progressive decrease in the number of positives and in the intensity of the reactions, till in the second week two-thirds and in the fourth week nine-tenths of the total cases were negative. Almost 90 per cent, of the original positives showed this characteristic loss of the Dick-positive state. It would appear that this change occurs less readily in young children. Fluctuations in the reaction during the course of the illness are very uncommon, if indeed they occur at all.

Of eleven cases which failed to show the above change two relapsed. In the other 149 cases no relapses occurred.

Pseudo-reactions are uncommon. Two examples have been described. It is suggested that the use of heated filtrate may be unsatisfactory and that the mechanism of these reactions requires further study.

Some of the anomalous features of the Dick reaction have been briefly discussed. In the opinion of the writer these difficulties have been exaggerated, and they do not in themselves form sufficient grounds for concluding that the test is fallacious.

On the evidence at present available one must continue to regard scarlet fever as a specific toxaemia. The allergic conception of the disease is less convincing.

This section of the work deals with the routine bacteriological examination of 2144 samples of water, of which 1102 contained lactose-fermenting bacilli, 4333 strains being isolated. Twelve strains which liquefied gelatine and 24 which gave anomalous MR and VP reactions were excluded from the coliform group; the remaining 4297 cultures were classified on the basis of the MR, VP, indol, citrate and uric acid tests.

In the routine laboratory examination of specimens of faeces and urine, from time to time certain Gram-negative bacilli belonging to many different groups are encountered, which morphologically show no appreciable differences from the Gram-negative bacilli of the coli-typhoid group, but which however ferment the usual carbohydrate media employed in differentiation with the formation of acid only. Some ferment lactose quickly, others more slowly, and many not at all, but as with the other media no gas is formed. These organisms might be considered as belonging to the so-called B. coli anaerogenes group— a somewhat loose term which might include many different strains, some perhaps related to the colon group, others belonging to and related to the group of dysentery bacilli, and others showing no relationship to either.

For the measurement of the temperature of exposed skin surfaces, we have reached the conclusion that the most accurate instrument is a radiation thermopile suitably screened from the effects of wind. As the thermopile does not actually touch the skin it does not interfere with the cutaneous circulation; neither does it hinder the heat-loss from the skin surface. Readings are simply and rapidly made; with the Moll thermopile and the Cambridge unipivot galvanometer used by us a reading can be taken in 4–6 sec. The readings are not influenced by wind if the thermopile is screened, and as the temperatures are measured as differences from that of a blackened surface of known temperature, change of air temperature does not upset the results. The apparatus is easily portable.

By rolling a mercury thermometer over a small area of skin the temperature can be estimated with but very slight error. This method is a reliable one for use where other apparatus is not available; but, it has the disadvantage that each observation takes from 1 to 1½ min. Accurate estimates cannot be obtained by this method in the special cases when the skin temperature is subject to rapid variation.

Under steady conditions accurate estimates can also be made by means of a clinical thermometer protected by a cork wedge, but each observation takes from 4 to 5 min.

Of the types of thermo-junction tested by us the simple Lewis type of junction attached and protected by a strip of surgical tape appears to give the most accurate results. The average error, taking the thermopile values as standard, was only 0·5–0·8° C, and the thermo-junction temperatures were consistently higher than the thermopile values by about this amount.

The Benedict type of junction also gives results which compare reasonably well with those obtained from radiation measurements. In our observations the average error with this type of junction was 0·7–1·3° C, and the error usually had the effect of giving too high a value for the thermo-j unction temperature. Other observers, however, have measured temperatures with this type of junction which appear to be somewhat low, and it appears possible that the temperature of the observer's hand may have influenced the readings obtained.

Forms of apparatus in which the thermo-junction and its leads are exposed to the effects of the air are liable to give very erroneous estimates of skin temperature. In our own comparisons the skin temperature was underestimated by 3–3·5° C. when the Strauss thermo-junction was used; and examples have been drawn from the literature which suggest that, with other apparatus in which the junction was exposed, the temperature was underestimated. If such forms of apparatus are used for measuring skin temperatures beneath the clothing, they may yield fairly reliable results, but in exposed positions considerable errors may arise. This liability to error is particularly serious where there is a wide range of air temperature and of air movement.

Skin temperatures can be measured with considerable accuracy by means of an electrical resistance thermometer.

1. Eighty-seven specimens of septic pus obtained from patients suffering from recent and old infections were examined fully bacteriologically and cytologically and were sterilised at 60° C. for 2 or 4 hours. The heated samples of pus were used for our experiments.

2. Glycerine extracts were prepared of the pus by two methods referred to in detail in the text.

3. The digestive action of the samples of sterile pus and of their glycerine extracts were tested on inspissated blood serum, gelatin, milk, egg and hydrocele saline. Digestion occurred on all these media in varying degrees with the specimens of pus, but glycerine extracts were more active.

4. It was found that the addition of pus or glycerine extracts of pus with various strains of Bacillus typhosus, B. paratyphosus A, B and C, B. gaertner and B. shiga to milk, produced clotting of the medium at 37° C. in the majority of our experiments.

5. If pus was heated at 60° C. for as long as 6 hours its digestive manifestations were not affected, but 80° C. for 20 min. or 100° C. for 10 min. completely destroyed the digestive activity.

6. At 22° C. the digestive action of pus was weakly manifested, while in the ice chest no reaction whatever took place.

7. Clotting of the medium occurred when pus was added to killed growths of B. typhosus and B. paratyphosus A in milk, but not with B. paratyphosus B or B. gaertner.

8. Human milk did not clot with pus and these organisms.

9. A large number of observations were made with serum exudates from pus, either after filtering through a Seitz E.K. filter or after heating at 60° C. It was found that the filtered or heated fluids might have a similar or a weaker action as compared with pus, or they might be inhibitory.

10. The white cells from several cases of chronic myeloid leukaemia, chronic lymphatic, the myeloblastic termination of chronic myeloid and acute leukaemia, were examined in the same manner as pus. The cells of chronic myeloid leukaemia acted in every way like pus, those of chronic lymphatic and their glycerine extracts were quite inactive; those of acute leukaemia corresponded to chronic lymphatic, while those of a myeloblastic termination gave a weak digestive reaction.

11. Specimens of blood serum from normal human beings and from patients with acute infections, and some specimens of body fluids before and after filtering, were found to inhibit the clotting of milk inoculated with pus and the microbes.

12. Twenty-two specimens of tuberculous pus obtained from abscesses and from pyo-pneumothorax, and seven samples of tuberculous sputum, were examined fully, but with special reference to their cytology.

In eight cases the pus showed no digestive action and no clotting of milk with the microbes, in nine cases a feeble reaction occurred, and in five cases the reactions were like those of pyogenic pus. Thus seventeen of the specimens could bedistinguished readily from pyogenic pus; in the five positive specimens polymorphs were numerous, but one of these cases was complicated by a secondary infection. In every sample of tuberculous sputum polymorphs and tubercle bacilli were numerous and the reactions corresponded to those of pyogenic pus.

Culbertson (1932) has recently described a method for estimating the antibody content of antisera against crystalline egg-albumin. He determined by tests on supernatant fluids the point at which antigen and antibody neutralised each other. At this neutralisation point he found that antigen and antibody combined in a ratio of 1 to 13, and that the amount of precipitate nitrogen was maximal. The ratio 1 to 13, he stated, held for all the precipitates in the post-zone where antibody was in excess.

The Isle of Ely is the northern half of the geographical County of Cambridge-shire and forms in itself a separate administrative county. It is the heart of the fen country, and its population is one which long retained a degree of isolation and independence tending to preserve in its members certain mental, and perhaps physical characters peculiar to themselves. It is interesting to recall that from this neighbourhood came Boadicea, Queen of the Iceni, and Hereward the Wake, who proved such stubborn enemies to the conquerors of their country.

The serious problem presented by the high prevalence of severe pulmonary tuberculosis in early adult life in the Highlands and Islands of Scotland is exemplified by the figures in the following table, for which we are indebted to the Department of Health and the Registrar-General for Scotland.