1. A fresh emulsion of tubercle bacilli in salt solution when used as the antigen will give about 90 % of positive results in cases of pulmonary tuberculosis, whilst in healthy persons the result is negative.

2. In cases suspected of pulmonary tuberculosis, the results of this test conform closely to those given by a combination of the opsonic index test with injections of tuberculin, and so may be of value in diagnosis.

3. Diseases other than tuberculosis have always been negative, but only a small number of such cases have been examined.

4. An emulsion of tubercle bacilli when used as an antigen must be freshly prepared immediately before use, and should be made from a young subculture.

5. Owing to the differences in complements, they should always be titrated in the presence of the antigen, and probably also in the presence of both antigen and normal serum.

6. Exercise does not seem to affect the result of the reaction in any way, but a course of tuberculin treatment leads to an increase in the complement-fixing bodies of the serum in some cases.

The method for the concentration of antitoxic sera suggested in this communication and now being used in this laboratory, presents a further step towards the desired goal, viz. the preparation, on a commercial scale for general therapeutic use, of antitoxic sera with a minimal amount of attendant protein.

In the concentration of sera on a large scale by the routine methods hitherto published the final products have shown a protein content of about 18 to 20 % with a potency per c.c. four to five times that of the original serum. The above described method yields, as a matter of routine, a final product with a protein content of about 17 to 19% and with a potency per c.c. as much as nine times that of the original serum. With the use of better processes the potency might be higher still.

It is worth while to concentrate by this method plasma or sera in which the unitage is so low that hitherto they would have been discarded as having too low a potency for use even after concentration.

The patient will receive a relatively higher percentage of antitoxic units per gram of protein than if the sera had been concentrated by other methods, for by this method the removal of 70% of the total proteins is ensured.

The heat denaturation of the proteins during the prolonged heating of the serum and consequent diminution of protein relatively to antitoxin may serve to minimise troubles with serum sickness.

In the British Medical Journal, Dec. 18, 1915, there is a letter by Mr Benians, in which he refers to the Toxic Bodies of the Bacillus of Malignant Oedema, and discusses the production of aromatic bodies by the action of bacteria on proteins. He also speculates as to the cause of the lessened production of indol in peptone culture media containing glucose, glycerine and other similar bodies. As the metabolic activities of some bacteria decompose these substances with the production of acid, Mr Benians wonders whether it is this acidity which so modifies the action of the proteolytic ferment that cultures, which, in the ordinary course of events are very foul remain sweet when glucose is present.

The object of this paper is to draw attention to the need of a further supply of sound dairy stock. Three main arguments in favour of this proposal have occupied our minds: (1) that the loss to the dairy industry through tuberculosis in cattle amounts to a considerable sum each year, (2) that there is serious loss in human lives due to bovine tuberculosis, (3) that, owing to their dearth in the country, there should be sufficient demand for sound dairy stock to place a farm devoted to the rearing of such cattle on a sound financial basis. The last part of this paper deals with a proposal to carry out this scheme.

During the year 1915, Drs F. Griffith, W. M. Scott and I have been investigating the meningococcus in the Board's Pathological Laboratory with the object of providing information which may be of service to the Board, particularly with reference to the carrier problem.

The present notes have been written in connection with official correspondence regarding the prophylactic inoculation against plague and the study of this and other health problems in India.

Simple agglutination tests divided into two main groups a series of 34 meningococci obtained from the cerebro-spinal fluid of cases of meningitis during the recent epidemic.

Certain of these strains of meningococci, which were either not agglutinated or only slightly by any of the sera employed, could be placed in one or other of the groups by the demonstration of their agglutinogenic capacity.

Certain individual strains in each of the groups were agglutinated to a less degree than the homologous strain, and certain strains were agglutinated by sera of both groups.

For further evidence as to specific relationship resort was made to agglutinin absorption experiments.

While the question, as to whether meningococci can be divided into independent groups by means of agglutinin absorption tests, must, at this stage of the investigation, remain open, the experiments detailed above indicate that variations in absorptive capacity between individual strains of meningococci are analogous to, though not in actual correspondence with, variations in agglutinability.

The non-contact naso-pharyngeal strains, culturally identical with meningococci, exhibited in relation to monovalent agglutinating sera prepared with cerebro-spinal meningococci, the same tendency to grouping as the cerebro-spinal strains and similar variations in agglutinability. The 28 non-contact strains, which have been investigated serologically, reacted to the following extent with one or other of the above-mentioned meningococcus immune sera:—5 showed complete agglutination in 1:400 or over, 10 in 1:200 or over, 6 in 1:100; 7 were not completely agglutinated in dilutions higher than 1:50. The first-mentioned 5 absorbed, from the respective agglutinating sera, the agglutinins for the homologous strains. From one of these 5, N.P. 10, a serum was prepared which was found to agglutinate strains in Group II. Of the 16 strains which agglutinated with meningococeus sera between 1:100 and 1:400, a few were tested as to their absorptive capacity in relation to two sera and, as will be seen from the absorption tables, showed evidence of agglutinin absorption. The absorption, though slight in amount, was equal to that occurring with the same sera treated with certain cerebro-spinal strains. The remaining 7 strains, which were agglutinated feebly by the meningococeus sera employed, are being subjected to further investigation (1) as to their agglutinability in relation to other cerebro-spinal meningococeus sera, (2) as to their capacity for producing agglutinating sera for cerebro-spinal meningococci. Taken as a whole, the serological results afford indication of a division of meningococci into two groups with some overlapping of each.

The theoretical explanation may be that the antigenic substance of the meningococeus contains one or other of two specific components, A and B, and sometimes contains both components, one of the two then being present in greater amount than the other. Consequently some strains produce sera with agglutinins of the A class alone; others create agglutinins of the B class alone; others produce both A and B agglutinins, with preponderance in some cases of A and in other cases of B. As regards agglutinability, again, some strains are capable of combining with A alone, others with B alone, and others with both A and B, but to a greater degree with the one than with the other.

Comparing the capacity of an individual strain for producing agglutinin with its capacity for combining with agglutinin, I find that in some cases these two capacities appear to coincide. But this is not a general rule. For example, a strain may have limited capacity for combining with agglutinin, but much greater capacity for producing agglutinin; again, it may combine with A alone, or mainly with A, but produce agglutinins in which B preponderates over A.

Absorption experiments, again, show that whilst there is sometimes a correspondence between capacity to absorb and capacity to create, or combine with, specific agglutinin, this correspondence is not a general rule.

These last two considerations show that the characteristics of different strains of meningococci, while affording a basis for division into groups, are closely inter-related, and, in fact, are connected by inseparable links, which appear to make it impossible to effect a definite cleavage between the one group and the other.

The above observations have been suggested by the results so far obtained, but further work on this subject is in progress, with special reference to the identification of the meningococcus in the naso-pharynx.

1. One hundred lepers were examined by Browning, Cruickshank and McKenzie's modification of the Wassermann reaction with positive results in 22 cases. The amount of complement deviated was in some cases exceptionally large.

2. In a control group of 110 non-leprous persons there were 11 positive reactions.

3. In only one of the lepers was there visible evidence of former venereal disease but 33 of the lepers admitted that they had suffered from syphilis or from chancres, and of these 33, 13 reacted positively, while only nine of the remaining 66 gave positive reactions.

4. In the control group, 21 admitted former syphilitic infection and, of these, eight reacted positively; among the remaining 89, who denied syphilis, there were three positive reactions.

5. There were 12 positive reactions among 44 cases of tubercular leprosy and 10 positive reactions among 56 cases of the anaesthetic type.

6. The average duration of the disease, among the 22 lepers who reacted positively, was four years and eight months, as compared with an average of three years and eight months for the 78 patients who reacted negatively; but among the latter there were many old-standing cases.

7. Seventeen of the 22 positive cases were in an advanced stage of leprosy and in some of them the disease was progressing; but among those lepers who reacted negatively there were also many advanced and progressing cases.

8. Serum from the lesions in 10 of the lepers who reacted positively was examined by dark-ground illumination, but in no case was the Treponema pallidum found.

9. The luetin test was applied to 21 lepers, with negative results in every instance; 13 of these cases gave positive and eight gave negative Wassermann reactions. The test was also applied to a control group of non-leprous persons selected because they were likely to be latent syphilitics. In this group there were 11 positive luetin reactions.

(1) The maximum period during which meningococci may be isolated from the naso-pharynx of convalescents exceeds three months.

(2) Meningococci were isolated from the naso-pharynx and proved identical with those isolated from the spinal fluid of the same patient in seven cases.

(3) In two of these cases the type of meningococcus found in the naso-pharynx at first resembled exactly that found in the spinal canal of the same patient, and later was persistently replaced by a meningococcus differing markedly in serological reactions from the spinal strain.

(4) Micro-organisms indistinguishable from meningococci by microscopical and cultural methods (including fermentation tests) were found in the naso-pharynx in 22% of 138 individuals, non-contacts, from an urban population (Lambeth out-patients).

(5) With 63% of these organisms the serological tests confirmed their identity with or close relationship to meningococci; they agglutinated specifically with anti-meningococcus serum and exhibited a tendency to fall into the same serological groups as the spinal strains.

(6) Their agglutinating properties were not, in general, so strongly marked with the sera used as those of the known pathogenic strains but they showed definite absorption of the specific agglutinm. They appeared to differ from the majority of the spinal strains not in the quality but in the quantitative intensity of their specific affinities: some spinal strains, however, resembled them in this.

(7) Thus, in 13·7% of the 138 non-contacts micro-organisms were found in the naso-pharynx indistinguishable by any test from strains of meningococci known to have caused meningitis: these are regarded by the writer as meningococci and the individuals harbouring them as meningococcus-carriers.

It has been already shown by Darwin and others that reproduction is a function of environment and that unfavourable conditions of life are likely to increase the number of seeds formed or offspring produced; hence so many are reproduced that the chance of the species being perpetuated is maintained, despite the unfavourable conditions for survival. To extend this idea, and say that a dying species tends to reproduce faster than one actively evolving, is a suggestion worthy of enquiry. It has been argued that the varying birth rates in man may to some extent reflect the future biological possibilities of his race. In so far as all environments are really functions of time, or, to put it another way, we measure the nature of an environment by the length of time it takes to produce a certain result, it is quite a natural sequence to consider the effect of time, that is, age on fertility. Dr Matthews Duncan and others have dealt with the immediate effect of time, that is personal age, and the question of the transmitted effect, if any, remains to be considered. If the idea that a species which is dying out tends to reproduce more rapidly, holds good for man, then our previous finding, that the later born do not on the average live so long as the earlier born, would suggest that they might possess as compensation an enhanced fertility. To solve this problem we must correlate the number of offspring produced by each unit with the age of the parents when he or she was born, the reproductive period being made constant.

A vaccine may, in general, be denned as a standardised suspension of killed bacteria. It is true that in a few instances living organisms are employed as vaccines as in the case of the Haffkine prophylactic for Cholera and the sensitised vaccines of Besredka. Notwithstanding these few exceptions it is suspensions of killed bacteria which are in most general use therapeutically as vaccines. According to Wright's method the bacteria employed in the preparation of a vaccine are killed by heat, the temperature actually employed ranging from 53° C. to 65° C. for one half to two hours. This method of sterilising vaccines has been largely employed, but has recently been subjected to much criticism. It has been stated that employment of heat in the sterilisation of vaccines has impaired the value of the vaccine, the heat coagulating albumin, increasing the toxicity and diminishing the immunising properties of the vaccine.