Notwithstanding several efforts, a satisfactory method of serological diagnosis of foot-and-mouth disease has not been arrived at. This uncertainty of serological methods delayed the discovery of the plurality of type of the virus, although the observations of epizootics and the irregular results obtained by active and passive immunisation suggested multiplicity of type. Stimulated by such observations, Vallée and Carré (1922) experimented with two viruses of foot-and-mouth disease, one of which was of German and the other of French origin. They were able to show by experimental infection, confirmed by subsequent testing for active immunity, that cases of foot-and-mouth disease with the same clinical course and symptoms could be caused by two distinct types of virus. These they called A (Allemand) and O (Oise). The only difference between these two types was their inability to produce reciprocal immunity. The existence of more than one type of virus has been confirmed in England by Stockman and Minett (1926), and by Bedson, Maitland and Burbury (1927); in Germany, by Waldmann and Trautwein (1926), and Trautwein (1927); in France, by Lebailly (1926), Olitsky (1927), and in Sweden, by Magnusson and Hermansson (1926).

This investigation of the incidence of tumours of the respiratory tract in Leeds was prompted by a paper read by Duguid before the Pathological Society of Great Britain and Ireland in January 1927, and published in the Lancet later in the same year. He analysed all the available post mortem records of the Manchester Royal Infirmary and showed that the incidence of intrathoracic cancer at autopsy in Manchester has steadily increased during the period of years 1886–1926 from 1·58 per cent, to 2·57 per cent.

Organisms which appear to be morphologically, culturally, and serologically identical have been recovered in four separate outbreaks of illness suggestive of dysentery.

They have been readily isolated in considerable numbers from all cases examined in the early phase of the attack.

When 1 per cent, peptone water is used as a basis for carbohydrates these organisms usually leave lactose, mannite, dulcite, and saccharose unaffected but ferment glucose and maltose with the production of acid. Barely, a minute amount of gas is also produced from glucose and occasionally slight acid and gas from dulcite. On the other hand, when Lemco broth (Dudgeon and Pulvertaft, 1927) is used as a basis, glucose, dulcite, and maltose are consistently fermented with the production of acid and gas.

Agglutination tests against normal sera and against anti-sera prepared from the dysentery and paradysentery bacilli and from B. paratyphosus A are uniformly negative but strains of the organism derived from all four sources are agglutinated to approximately the same titre by an anti-serum prepared from one of them although this anti-serum has no effect on three organisms whose reactions present some degree of similarity.

The organisms do not appear to be toxic for rabbits.

With all patients affected in these outbreaks, whose blood was available for examination, the serum has shown the presence of specific agglutinins which could not be demonstrated in normal serum.

On the whole, therefore, the evidence suggests that these organisms may be responsible for the diseased condition.

In 1917 and 1918 Tunnicliff announced that she was able to obtain cocci from the blood of cases of measles in the pre-eruptive and eruptive stages of the disease. It was claimed that anaerobic methods were necessary for their isolation, but after the initial growth appeared these organisms could be sub-cultured aerobically. Later, this worker (Tunnicliff, 1919) found a similar organism to be the predominating species in cultures obtained from the sputum of acutely ill cases. Caronia (1923) reported that he was able to isolate with great regularity a small diplococcus from the blood of measles cases by using the Tarozzi-Noguchi medium.

(1) The concentration of small-clumping (O) typhoid agglutinin in the serums of a group of recently inoculated persons was found to be, on an average, distinctly higher than that of a group of uninoculated persons.

Additional proof that this is the result of the inoculation is given by tracing the curve of production of “O” agglutinin in a healthy adult immediately after inoculation.

(2) The serums of healthy persons show a moderate but extremely variable power of clumping typhoid “O” suspensions. Expressed as a titre, the normal limit varies between 1 in 50 and 1 in 200, according to the sensitiveness of the suspension used. Expressed in standard units of “O” agglutinating power the normal limit is 10 standard “O” units.

(3) Methods of preparation of permanent suspensions for the estimation of “O” agglutinin are discussed and Felix's recommendation of the alcohol method is confirmed. The agglutinability standardisation of suspensions of this kind is described.

(4) Broth suspensions treated with 0·1 per cent, formalin, such as are used for the ordinary Widal reaction, are shown to be capable of detecting “O” agglutinin, but to be less suitable for its estimation than alcohol suspensions.

(5) The place of small-clumping “O” agglutination in the diagnosis of typhoid fever is discussed, and a method of performing the combined “H” and “O” test in inoculated persons is suggested, wherein a compromise is effected between the customary quantitative measurement and Felix's qualitative “one-dilution” method.

In the present study an attempt has been made to determine the relative importance of several factors on the mortality rates of infancy. In view of the differences in the rates at the several ages under one year and of the differential decline in these rates within recent years, it has been suggested that for any complete consideration of the death rates in infancy, some subdivision of the rate, either of a biological or temporal character, must be effected, and each of these subdivisions examined separately. The infant mortality rate has been treated in three broad categories, namely, the antenatal, neo-natal and post-natal death rates; and it has been shown that each of these depends on different factors.

Considered as death rates per unit of time the neo-natal rate is much higher than at any other period of life. The ante-natal death rate is much lower than this, and the post-natal rate lowest of all.

In relation to these rates, the influence of three, presumably important, factors have been measured. These are:

1. The provision of skilled attendance to mothers in childbed.

2. The health of the mothers.

3. Environmental and social conditions.

The indices used as measures of these three variables and their limitations have been pointed out. The author feels only too conscious of these limitations and, with such vital statistical data as the only indices available of the factors the influence of which on the mortalities of infancy it is desired to measure, it is probable that any conclusions drawn from such an analysis should be accepted with some degree of caution and reserve. Nevertheless. I am firmly convinced that even these (to the clinician and administrator) rather crude results are immeasurably superior to expressions of opinion, unsupported by facts, so frequently found forming the basis of much of the medical literature on the subject. That we have so relatively little exact quantitative knowledge of the influential factors concerned in the growth, nutrition and mortality of infants is surely not for lack of opportunity of collecting the requisite data. An admirable machinery for such a purpose—the various maternity and child welfare centres—is in extensive operation throughout this country; and if the medical officers in charge of these centres could only be persuaded to collect and analyse (or have analysed) periodically the data contained in suitably framed and completed questionnaires, many questions of scientific importance as well as of the efficacy of administrative efforts would soon cease to be subjects of controversy.

Our results show that, of these factors, only the provision of skilled medical assistance to mothers in childbed is of importance in connection with antenatal mortality. The general health of the mother and external environmental conditions have no direct influence on the death rate at this period of life. The magnitude of the correlation leads to the further conclusion that a great part of the still-birth rate is not to be controlled by improvements in even all of these factors.

The neo-natal death rate is related both to variations in external environment and in the obstetrical assistance available for mothers in childbed. At this state of life, again, the health of the mother has no substantial influence on the death rate. External surroundings and the quality of the obstetrical assistance afforded to the mother are of approximately equal importance in determining these rates; but here again the conclusion is advanced that the greater part of the death rate at this stage of life is beyond human efforts of control.

The post-natal death rate seems to offer the greatest scope for administrative measures. In this case the health of the mother would appear to come first in order of importance, environment also is of some importance, whereas the effects of variations in obstetrical services have now ceased to be reflected on the mortality of infancy.

In isolated rural communities there is a part of the post-natal death rate which could be eliminated by the speedy arrival of skilled medical assistance.

Foreign statistics have been collected and analysed to enquire into the causation of still-births. An obvious defect in these was pointed out, namely, the large proportion of deaths due to unknown causes. A comparison of these figures with those collected from several maternity hospitals has shown that hospital figures give a biassed view of the problem. The proportion of deaths due to causes in which the life of the mother as well as that of the foetus is endangered is greatly magnified, and consequently will produce a too optimistic estimate of the amount of amelioration which will result from increased attention to pregnant and parturient women. The statistics which have been given in this section show that in a really random sample of the population only a small proportion of still-births is the result of causes which can be controlled by this method, and that the chief causes of ante-natal death are developmental defects of the foetus and prematurity.

A short study has been made of certain statistico-anatomical features of the foetus and infant. From this it has been inferred that the foetus is physically in a state of extreme instability, that the conditions which kill in utero are rapidly fatal to the foetus, and that this instability is a somewhat more prominent feature in the male than in the female. As infancy advances, visceral variability decreases steadily, so that it would seem probable that some time is necessary for the foetus to adapt itself to its new mode of existence after birth. This state of unstable equilibrium in early life may provide some reason for the higher mortalities at these ages.

(1) The review of the published data furnishes additional evidence in support of the view that no technique whatsoever, Dreyer's technique included, based on the quantitative method of the agglutination reaction hitherto used, is capable of affording a differentiation between inoculation and infection agglutinins.

(2) These techniques are concerned always exclusively in the demonstration of the labilotropic H agglutinins of B. typhosus and B. paratyphosus A. and B. and it is the behaviour of these agglutinins that is the responsible factor in producing the phenomena.

(3) In various febrile conditions in inoculated individuals these H agglutinins undergo a re-stimulation resulting in a curve of agglutination which is indistinguishable from that due to specific stimulation. The re-stimulation of the labilotropic inoculation agglutinins is of the same nonspecific character (i.e. heterologous) in the course of enteric infections as in the course of other febrile diseases.

(4) The observation of this non-specific re-stimulation is independent of the technique used; living bacilli and suspensions preserved with phenol or formalin (Dreyer's technique included) do not in this respect behave differently.

(5) The proposed qualitative method for the Widal test depends, in inoculated individuals, exclusively upon the behaviour of the stabilotropic O agglutinins. In their presence it is capable of affording the certain diagnosis of an enteric infection; in their absence the negative result of the test is not conclusive; if T.A.B. vaccine has been used it is only possible to diagnose enteric group without being able to differentiate typhoid from paratyphoid A. or B.; if T. vaccine has been used then A. or B. infection can be differentiated but not T.

(1) The conclusions previously arrived at by means of the qualitative method of the Widal test were fully confirmed. By eliminating the labilotropic H agglutinins from any consideration—in the case of previously sensibilised individuals—agglutination due to the specific stimulation in active enteric infection can be distinguished definitely from that due to the nonspecific re-stimulation by various febrile diseases.

(2) Normal and immune O agglutinins for B. typhosus and B. paratyphosus A. and B., as well as those for B. proteus X 19, are not liable to non-specific stimulation in the course of various febrile diseases.

(3) One more of the supposed differences in nature between the Widal test and the Weil-Felix test is thereby eliminated.

(4) The difference in the response to non-specific stimulation shown to exist in stabilotropic and labilotropic agglutination seems more likely to be one of degree than one in nature and needs further investigation.