bluuebunny/crossref_metadata_2025 huggingface dataset:
Haemolytic streptococci in the dust of hospital wards, and their relationship to infection: A report to the Medical Research Council
Authors: Edward Derrick G. ff.
Published: May 2009

1. A weekly examination for haemolytic streptococci was made of the dust of two hospital wards; observations lasted in each ward for about six months. The wards chosen were a combined ear, nose and throat and eye ward used for adult patients, and a children's ward.

2. It was found that on an average for the whole period the dust of the former ward contained 300,000 haemolytic streptococci per gram and the dust of the latter 250,000 per gram.

3. Representative colonies of haemolytic streptococci grown from each sample of dust were examined serologically to determine their group. About 33% of those isolated from the E.N.T. Eye ward were group A and about 80% of those from the children's ward.

4. In order to determine the relationship of the streptococci in the dust to streptococcal infection among patients and staff, throat swabs and swabs from septic lesions were regularly examined.

5. In the children's ward 27·8% of 270 patients were found to be infected with haemolytic streptococci either on admission or at some time during their stay in hospital. The incidence of infection acquired in hospital was more than 12·2%. About two-thirds of these infections were latent.

6. Group A streptococci isolated from the dust and swabs were identified serologically according to type. It was noted that the occurrence of a particular type in the dust often resulted from the presence of one or more infected persons in the ward.

7. It was, however, frequently noted that a particular type made its first appearance in the dust when it could not be cultured from any of the swabs. It is possible that these strains were introduced to the ward by visitors, such as patients' relatives and friends or patients from other wards coming for septic dressings.

8. No conclusive example of a hospital cross-infection conveyed by dust was noted.

I wish to thank Dr T. J. Hennelly and Dr D. G. Morgan, Medical Superintendents of the two hospitals, for giving me the facilities to carry out the investigation; also Dr S. T. Crowther and Dr Duncan Davies, and the sisters and nursing staff for their assistance and co-operation. I am especially indebted to Dr V. D. Allison for his helpful advice and criticism.
Studies in the dynamics of disinfection: I. New data on the reaction between phenol andBact. coliusing an improved technique, together with an analysis of the distribution of resistance amongst the cells of the bacterial populations studied
Authors: Jordan R. C. , Jacobs S. E.
Published: May 2009

1. The action of phenol onBact. colihas been studied quantitatively in detail under such conditions that unfavourable circumstances other than the presence of the germicide were as far as possible eliminated. Briefly, this involved the addition of phenol solution directly to a large volume of culture developed under rigidly standardized conditions.

2. When the mortality exceeded 95% the variation between the numbers of colonies on replicate plates, when determining the numbers of survivors, was often excessive.

3. Under the conditions used the death-rate was not constant. First, there was a phase (1) of slow but increasing death-rate which merged gradually into a phase (2) of approximately constant rate which was also the maximum for a given phenol concentration. There are indications that the death-rate may decline towards the extreme end of the disinfection process.

4. The virtual extinction time (the time taken for the survivors to fall to 1 per ml. as determined by extrapolation of the log survivors-time curve) increased as the phenol concentration decreased, as also did the duration of phase 1. The latter occupied about 60% of the virtual extinction time when the concentration was 3·48 g. phenol per 1., but with rising concentration its duration decreased at a greater rate than the virtual extinction time so that at about 7 g. per 1. phase 1 was very short though still detectable. The standard errors of the virtual extinction times varied between ± 1·5% and ± 5·43%.

5. Using the probit method it has been shown that at low concentrations of phenol the distribution of resistance ofBact. coliis approximately normal when the resistance is measured in terms of the survival times.

6. The distribution of resistance was found to be normal at all concentrations of phenol used, when that resistance was measured in units of the logarithms of the survival times, with the exception that at the lower concentrations there was a sudden change in the slope of the probit-log survival-time line at about 20% mortality. This change became less marked with rising concentration and was probably absent at 8·00 g. phenol per 1.

7. After conversion into the dosage-mortality form, the data reveal that about 70% of the cells show an approximately normal distribution of resistance when the latter is expressed in terms of the dosage survived for a fixed time, provided that the exposure time is less than 50 min.

8. The distribution tends to be normal for longer exposure times when the resistance is measured in terms of the logarithms of the dosages survived. On this basis a change of slope of the probit-log dosage line is observed as in the case when resistance is measured in terms of the logarithms of survival times.
Revaccination as a measure of immunity to smallpox
Authors: Horgan E. S. , Haseeb Mansour Ali
Published: May 2009

1. Serological methods for the determination of smallpox immunity are briefly discussed, and it is concluded that they are unlikely to provide a diagnostic method of sufficient accuracy.

2. Experimental work is recorded which shows certain differences in the response of previously vaccinated individuals, revaccinated simultaneously with a standard vaccine lymph and an elementary body suspension (vaccinia) of high potency. The significance of these differences is discussed.

3. The results indicate that although the advantage of the e.b. suspension over vaccine lymph is relatively insignificant, that of two insertions over one is very marked. In revaccination the routine use of one insertion only may result in a certain number of semi-immunes (vaccinoids) being erroneously reported as immunes.

4. It is concluded that if the two insertion technique be practised, persons showing immune reactions (negatives) may be considered, in all probability, as possessing full immunity to vaccinia-variola virus.
A pressure-operated safety circuit for use in high-vacuum serum-drying plants
Authors: Byrom F. B.
Published: May 2009

A form of Pirani vacuum gauge is described for obtaining a continuous record of the total residual pressure in a high-vacuum serum-drying cylinder of the Greaves-Adair type. The circuit incorporates an automatic relay which breaks the electric current heating the frozen serum if the pressure rises to a dangerous level, and so delays materially the onset of fusion of the serum.
The use of antiseptic sprays for air sterilization: A summary of a report to the Medical Research Council
Authors: Pulvertaft R. J. V.
Published: May 2009

Experiments on the bactericidal properties of mists were performed in a closed room of 850 cu. ft. capacity. The test organism was sprayed into the room through an Atmozon nebulizer operated from a mechanically driven Austin diaphragm compressor; the pressure was maintained at 7 lb./sq. in. Air to the compressor was taken through rubber tubing from an adjoining room to avoid accidental admixture of antiseptics into the air used to atomize the bacteria. The output of the nebulizer was 0·22 c.c./min. In the majority of the experiments the test organism was sprayed for 2 min. To ensure that an adequate mist was being emitted, the culture was nebulized in the dark against a dark background, and examined frequently with a light beam. Even distribution of the mist in the room was ensured by convection currents from a large hot-water pipe which ran along the length of two walls about 2 ft. from the floor, and by a small electrically driven fan placed immediately behind the nebulizer.
Some bacteriological aspects of dehydrated foods
Authors: Haines R. B. , Elliot E. M. L.
Published: May 2009

1. Data on the maximum temperatures of growth of certain organisms, on the rate of toxin production byCl. botulinumand the rate of multiplication of certain Salmonellas, is given, as a basis on which to define the time and temperature of dehydration in the preparation of dehydrated foods.

2. It is concluded that 50° C. is the minimum temperature below which dehydration should not be carried out. Where some heating below this temperature is unavoidable, the period of such heating should not exceed 4 hr.

3. Data on the microbial changes in dehydrated foods equilibrated at various humidities indicate that bacterial growth is not expected below about 15 % water content. Some experiments on the death of bacteria at water levels below this are discussed.

4. Details are given of the general bacteriological examination of the process of dehydration on a commercial scale for dried soup, dried minced beef, dried carrot, cabbage and potato.

This work was carried out under the joint auspices of the Food Investigation Board of the Department of Scientific and Industrial Research, and the Ministry of Food, and is published by permission. The authors are indebted to Professor H. R. Dean for the provision of facilities, and to him, Professor G. S. Wilson, Dr A. W. Downie, and various other members of the Emergency Public Health Laboratory Service for help and advice.
A standardized method of disinfecting infected blood-clots
Authors: Gardner A. D.
Published: May 2009

1. A method is described for estimating the disinfecting power of chemical substances on small cylindrical blood-clots of standard dimensions (about 1·5 mm. in diameter) containing a measured number of bacteria (Staph. aureus). It is capable of giving guidance for the use of disinfectants under the described conditions.

2. No practicable disinfectant regularly sterilized heavily infected clots (400,000 cocci) in 5 min. at 17–20° C.

3. In 30 min. the following were the only substances that were uniformly successful with heavily infected clots: 2·5% iodine in aqueous KI solution; 50% Chloros, containing about 5% chlorine; 70% alcohol containing 0·1% acriflavine. (The first of the three was tested on a larger scale than the others, and its potency is therefore the more firmly established.)

4. Reduction of the number of cocci in the clot increased the range of effective disinfectant solutions. Thus with 4000 cocci per clot regular clot disinfection was achieved in 30 min. with the following additional solutions: ethyl alcohol 70 and 50%; Chloros 25%; phenol 2·5% and lysol 1·25%. A few tests indicated that Zephiran (and probably CTAB) at 1 or 2% concentration would also pass this less exacting test.
Bacterial infection and immunity in lower vertebrates and invertebrates
Authors: Bisset K. A.
Published: May 2009

A review is given of some of the literature concerned with bacterial infections and immunity in invertebrates and cold-blooded vertebrates. Among the former, insects have been most fully studied, although a certain amount is known of the immunological reactions of marine invertebrates. Diseases of insects are mainly generalized, bacteraemic conditions, and the great majority are caused by Gramnegative cocco-bacilli. Diseases of cold-blooded vertebrates also are usually generalized, but bacteria from a very wide variety of groups have been isolated from them.

It is probable that this resemblance in the infections of these widely separated groups of animals is due to the fact that, unlike mammals and birds, with whose reactions we are more familiar, the regulation of their temperature and the constitution of their body fluids is not exact. This toleration of wide variations of their own physical and chemical constitution must reduce their sensitivity to the changes produced by infection, and hence decrease the likelihood of a local reaction, designed to confine the invading organism to the immediate region of its point of entry, i.e. a local inflammation.

The production of humoral antibodies appears to be almost universal in the animal kingdom, although greatly affected by changes in temperature.

The effect of temperature upon the balance between host and parasite is also discussed. This question bears upon the problem of occasional pathogenesis by saprophytes. Even among mammalian pathogens the borderline between parasite and saprophyte is an indistinct one, especially in such cases asProteusandPseudomonas pyocyanea, and even those species which are usually regarded as exclusively parasitic may readily be constrained to adopt a saprophytic existence on artificial culture. Where cold-blooded animals are concerned the boundary is even more difficult to draw, and it is possible that under suitable conditions, bacteria which are normally saprophytes may be capable of causing infection. This point will be impossible of proof until more sensitive means of definition of bacterial species are discovered.
Studies in the dynamics of disinfection VIII. The effect of lethal temperatures on standard cultures ofBact. Coli.I. A detailed analysis of the variations of death-rate with time
Authors: Jordan R. C. , Jacobs S. E. , Davies H. E. F.
Published: May 2009

1. Whole cultures ofBact. coligrown under carefully controlled conditions have been subjected to the action of heat at temperatures ranging from 47 to 55° C. and the survivor curves determined.

2. The occurrence of excessive variation between replicate plates of counts made when the mortality exceeds 95 % was very much less evident than when phenol was the lethal agent.

3. At temperatures of 35° C. and below, disinfection of the cultures was never complete, as a permanent population of cells became established. In some cases the numbers of heat-resistant cells reached nearly 0·01 % of the original population, but great fluctuations were observed.

4. The death-rate during the active part of the disinfection was not constant but, in general, increased with time. In the faster disinfections this increase was difficult to detect and the logarithmic death-rate appeared to be virtually constant, but the increase is nevertheless believed to have been present in all cases.

5. The data for all the experiments have been combined to give a composite disinfection curve from which it was concluded that the death-rate was low at first but rose to a maximum at which it remained constant until the mortality had reached at least 99·99%.

6. This finding led to the decision to treat all the experiments as if the regression of log survivors on time had been linear between mortalities of 90 and 99·99%. The standard errors of the calculated regression coefficients were small, so that this method of treating the experimental data appears to be justified.

The authors wish to express their gratitude to Messrs I.C.I. (Pharmaceuticals) Ltd. for their valuable financial assistance, which has enabled one of us (H. E. F. D.) to devote his full time to this work.
Nasal filtration of airborne droplets
Authors: Boyland E. , Gaddum J. H. , McDonald F. F.
Published: May 2009

Apparatus for determination of the penetration of particulate airborne material through the nose is described. The penetration of aerosols of liquid particles produced by a spray has been measured in rats, rabbits, goats, sheep and men. The penetration decreased with increase in the rate of flow through the nose.

Particles of the order of I μ diameter penetrate the nose at all rates of flow, while very few particles larger than 15 μ can penetrate except at low rates of flow.
Phage-resistant and phage-carrying strains of lactic streptococci
Authors: Hunter G. J. E.
Published: May 2009

1. The types of resistance acquired by certain related strains of Str. cremoris as a result of phage action were investigated.

2. Some partially resistant forms of Str. cremoris were able to ‘carry’ phage in symbiotic association when subcultured daily in milk for long periods of time.

3. The phage ‘carrying’ power of the cultures was of a non-inherent nature. ‘Purification’ of the phage-carrying cultures by plating resulted in the production of phage-free colonies.

4. Under certain circumstances, the presence of symbiotic phage in a culture gave a measure of protection against attack by other phage races.
The synergic action of penicillin and sulphathiazole onS. typhi
Authors: Thomas John C. , Hayes William
Published: May 2009

Due to earlier reports of the relative resistance ofS. typhiand other members of the salmonella group to penicillin, and to the prevalent preoccupation of most workers with those organisms against which treatment with penicillin was more obviously applicable, little attention was payed to the chemotherapy of enteric fever until Bigger (1946) published his findings on the synergic action of a more reliable guide to the occurrence of synergism than sterilization, might be demonstrated. In conformity with the previous results, however, treated broth was also used to demonstrate synergic killing effect. Results are given in Table 12.

T455, when tested under similar conditions, was inhibited by 6·25 u./ml. penicillin and showed a twofold inhibitory synergism in the presence of sulphathiazole. It will be seen that all the strains tested showed some degree of inhibitory synergism but that, in the majority, the concentration required to inhibit growth was considerably higher than in the case ofS. typhi. With the majority of strains the concentration of penicillin required to destroy the inoculum in 24 hr. at 37° C. was greater than 25 u./ml., even in the presence of sulphathiazole, while in one case no bactericidal synergism at all penicillin and sulphathiazole againstS. typhi. Although, therefore, much work has been published concerning the synergic action of the sulphonamide group on penicillin activity in general, little information is available on thein vitrobehaviour of the salmonellas in this respect despite the present wide, though tentative, application of the principle in the treatment of enteric fever. The experiments presented above were undertaken with the object of confirming those findings hitherto reported and of studying in detail the effects of sulphathiazole and penicillin, and of combinations of the two, on the salmonella group, with special reference toS. typhi.

For purposes of discussion it is convenient to summarize our results under the principal headings used in the text.
The adjustment of biological assay results for variation in concomitant observations
Authors: Finney D. J.
Published: May 2009

When individual responses in a biological assay show considerable variation associated with the values of a concomitant variate, covariance analysis may be used in order to adjust the mean responses and to improve the precision of the assay. Usually this is preferable to the choice of an adjustment which involves an arbitrary assumption about the effect of variations in the concomitant variate on the measured response. Published accounts of the process are open to certain theoretical objections, though they may be sufficiently exact for most practical purposes.

The present paper describes a method of calculating the relative potency, and its precision, which may be a little more laborious, but which is in full accord with standard statistical practice. The computations are illustrated on data from a prolactin assay by the pigeon crop-gland technique, in which the final crop-gland weight showed a positive correlation with the body weight at the start of the assay. The results are compared with those obtained either from the unadjusted crop-gland weights or from these weights expressed as proportions of body weights. The covariance method leads to a more precise estimate of the potency of the test preparation than do either of the others; there is evidence, however, that the increase in precision will not necessarily be large unless the correlation between the response and the concomitant variate is very close.

In a final section, the full statistical tests of assay validity in the covariance analysis are described; these are lengthy, and fortunately are required only when the validity is in considerable doubt.

The methods of adjustment have been described in this paper with respect to an assay depending upon parallel regression lines of responses on the logarithms of doses. They may be adapted for use with ‘slope-ratio’ assays (Bliss, 1946; Finney, 1945; 1948; Wood & Finney, 1946), in which the regression of response on dose itself is linear. So far the need for adjusting for concomitant variation in these assays seems not to have arisen, and discussion of computational details may be postponed until the need is felt.
The conglutination phenomenon. II. The technique of the conglutinating complement absorption test compared with the haemolytic complement fixation test
Authors: Hole N. H. , Coombs R. R. A.
Published: May 2009

1. A brief introduction has been given to the conglutination reaction.

2. The technique used by us for carrying out the conglutinating complement absorption test has been described in detail and compared with that used for the haemolytic complement fixation test.
The bacteriological examination of molluscan shellfish
Authors: Clegg L. F. L. , Sherwood H. P.
Published: May 2009

Section I

A standard bacteriological test for molluscan shellfish should fulfil certain requirements stated: briefly, the test should show the degree of pollution, be accurate and rapid, and self-sufficient, not requiring subsequent confirmation. Review of the subject leads to recommendations, first, to overcome the technical difficulties of preparing samples for testing; secondly, on the nature of the test. In preparation: external shell sterilization can usually be omitted, shell water should be discarded and replaced by sterile water to make a total volume three times that of the body tissues. Pooling of individual shellfish into one sample is acceptable in routine examinations. In the test: a solid medium is preferable to a liquid medium, giving more accurate results, and review of existing tests leads to the conclusion that the use of roll tubes of MacConkey agar incubated at 44° should meet the requirements of a standard test.

Section II

A modification was found necessary in the MacConkey agar: a mixture of 2 % gelatin and 5 % agar is used instead of the normal 2 % agar. Mechanical rolling devices for tubes are described and figured.

Among other critical experiments, 1000 roll-tube colonies grown at 44° from shellfish included 969 with + + − − ‘IMViC’ reactions and 979 acid and gas producers at 44°. The coefficient of variation among replicate tests of samples of shellfish and water in roll tubes was not seriously greater than that for colony counts in Petri dishes at 37° with ordinary MacConkey agar.

Colonies in roll tubes incubated at 44° can be counted as conveniently and accurately as those on Petri dishes, and, in general it is concluded that the new method is more satisfactory for estimation of faecalcolithan other methods at present in use.

Section III

Directions are given for the preparation of shellfish and inoculation into roll cultures, both for individual and for pooled examination, and the method of determining results is described.

The interpretation of results is discussed, and it is suggested that shellfish which in four out of five samples from the same source are free from faecalcoliin 1 ml. quantities of body tissue should be regarded as satisfactory for food. The presence of more than two or three faecalcoliper ml. of body tissue in any one sample calls for appropriate action according to the number present.
The standard error of an estimate of expectation of life, with special reference to expectation of tumourless life in experiments with mice
Authors: Irwin J. O.
Published: May 2009

An expectation of life limited to n years is properly defined by

to which the approximation usually used is
Record keeping for laboratory animals
Authors: Gridgeman N. T.
Published: May 2009

The amount of clerical work involved, and the ramifications of the record system used, in an animal laboratory, are conditioned by the purpose for which the colony is maintained, and dependent upon how anxious its custodians are to control its size and guide its future. If, for instance, ease of operation and minimization of clerking is to be the overriding consideration one may secure a good supply of young rats by the simple process of allowing a flock of adult animals the freedom of a warm room containing bedding and food. One enters at intervals to clean and feed, and, eventually, to remove, for experimental work, those youngsters that look big enough to fend for themselves, taking care, at the same time, to leave a few of each sex to grow to maturity and guarantee the next generation. An occasional census of population and production is all that is necessary in the way of records.
The source of infection in Pemphigus neonatorum
Authors: Parker M. T. , Kennedy J.
Published: May 2009

An outbreak of eighteen cases of pemphigus neonatorum in a maternity department is described.

Strains ofStaph. aureusisolated from the infants, the mothers and the staff during several weeks of intensive investigations were classified by phage typing.

The findings indicated that, during the latter part of the outbreak at least, the adults were not the source of infection.

There was evidence of wide dissemination of the epidemic strain ofStaph. aureusamong the healthy infants in the nursery. It is suggested that the main path of infection was from infant to infant.

Methods of controlling established outbreaks are discussed.
Quaternary ammonium compounds. A new technique for the study of their bactericidal action and the results obtained with cetavlon (Cetyltrimethylammonium bromide)
Authors: Davies G. E.
Published: May 2009

1. Some sources of error in the testing of quaternary ammonium compounds for bactericidal activity have been investigated. These resolve themselves into (a) errors caused by bacteriostasis, and (b) errors caused by the clumping of bacteria.

2. A suitable technique, free from these errors, is described.

3. Cetavlon in 0·1% solution is a powerful bactericide even in the presence of moderate amounts of organic matter.

4. One per cent Cetavlon will not kill spores at room temperature even when contact is maintained for several days.

5. Bacteria surviving the action of quaternary ammonium compounds retain their virulence.
Some observations on the reaction between horse serum and a pool of rabbit antihorse serum. II. An analysis of the antigens concerned in the production of multiple zones
Authors: Naylor G. R. E.
Published: May 2009

1. The reaction horse serum and a pool of rabbit antihorse serum exhibiting four α procedure optima has been investigated with a view to analysing the antigens involved in the production of the multiple zones.

2. The following conclusions have been reached regarding the antigenic constitution of horse serum, a horse serum-albumin preparation and a horse serum-globulin preparation: Horse serum consists of at least five antigens. The horse serum-albumin preparation contains three antigens, two of which are probably impurities, one of these being a globulin. The horse serum-globulin preparation consists of three antigens and evidence was obtained of a fourth. Electrophoretic analysis of these protein preparations gave concordant result.

3. Multiple zones of rapid particulation in the precipitation reaction are due to the independent activity of multiple antigens and their homologous antibodies.

4. The absorption of precipitin from a mixture of antibodies by a mixture of antigens at a single α procedure optimum is both a useful and a practicable procedures.

5. Attention is drawn to the fact that the method of antigenic analysis used in the present series of experiments, involving the correlation of α; procedure optima occurring in the parallel titrations of a single antiserum against a mixed antigen and equivalent concentrations of physically or chemically prepared fractions of it supplemented by absorption of precipitins at individual and multiple α precedure optima and retitration of the absorbed sera, could be applied to the identification and nomenclature of proteins occurring in natural mixtures, and also to the quantitative and qualitative appraisal of the purity of proteins prepared by physical or chemical means. The method does not rely on the preparation of highly purified protein samples containing a single antigen.
The morphology of the genusLeptospiraas shown by the electron microscope
Authors: Babudieri B.
Published: May 2009

Several species ofLeptospirahave been studied by means of the electron microscope. Their morphology is described. TheLeptospiraconsists in a long homogeneous cylinder of protoplasm, enveloped in a very thin anistic membrane and wrapped around a slender axistyle. Vibratile structures and granules generally are lacking.

The appearance of Leptospiras differs according to different methods of fixation used and according todifferent physical or chemical treatmentsto which they are subjected.
The survival of bacteria in dust. I. The distribution of bacteria in floor dust
Authors: Lidwell O. M. , Lowbury E. J.
Published: May 2009

The viable bacteria in 10 mg. portions of dust were estimated by shaking with 5 ml. of Ringer's solution in 1 oz. bottles containing glass beads. The extract was allowed to stand for a few minutes, and 0·1 ml. amounts were then plated out at suitable dilutions. Successive portions from the same sample of dust showed very great variation in the bacterial counts, and this variation has been examined in series of twenty such portions. The distribution of the counts for three groups of organisms appears to approximate to a log-normal form, and the graphical estimate of the log-median is taken as a suitable parameter for the study of the influence of environmental factors on the survival of dust flora.
The carcinogenic activity of some petroleum fractions and extracts. Comparative results in tests on mice repeated after an interval of eighteen months
Authors: Woodhouse D. L. , Irwin J. O.
Published: May 2009

Woodhouse's experiments on the carcinogenicity of ten different fractions for the skin of mice have been analysed statistically. Two experiments separated by a considerable period of time were performed on each fraction.

A number of different measures of carcinogenicity were used. All agree in showing that

(1) The apparent carcinogenicity was greater in the 2nd series of experiments.

(2) There were significant differences in carcinogenicity. The fractions can be divided into three groups within which the carcinogenicities were about the same, viz. F H I K, B D G L E, M.
Biological assays with special reference to biological standards
Authors: Irwin J. O.
Published: May 2009

A paper on biological assays and biological standards might be expected to start with a definition. What is a biological assay and what is a biological standard? However, I shall for the moment make the somewhat doubtful assumption that we all know the answer to those questions but shall return to them later, making a start meanwhile by discussing some aspects of the history of our subject.
The theory of amoebic surveys
Authors: Lancaster H. O.
Published: May 2009

(i) The theory of amoebic surveys and of related types of pathological surveys is discussed.

(ii) An inequality is derived,

whereXis the total number of carriers andX1,X2are the new carriers found at the first and second examinations.

(iii) Demonstrability is defined and several theoretical distributions of it are considered.

(iv) Demonstrability is shown not to be a constant in the populations considered.

(v) The danger of extrapolation is noted.

(vi) Life-table methods are introduced to treat some well-known published series.

(vii) A criterion for the adequacy of any estimate of the total carrier rate is given. The mean demonstrability of the outstanding carriers after successive examinations must form a decreasing series.

(viii) This criterion usually shows that the method of estimating the carrier rate forEntamoeba histolyticaas three times the proportion of positives at a single examination, or as the total number of positives picked up in six examinations, both give too low a carrier rate.

(ix) It is suggested that the investigation of the ‘carrier’ rate may in certain cases be merely a measure of ‘demonstrability’.

(x) Possible future lines of investigation of the problem are noted.
Statistical control in haematology
Authors: Lancaster H. O.
Published: May 2009

The value of ‘Statistical control’ in haematology has been demonstrated. After a short historical survey of the chief contributions to the theory of the technique of counting and of the application of the Poisson distribution in biology, the statistical theory of the distribution of cells in the haemocytometer is briefly described and examples are given of large sample methods of testing goodness of fit. Some of the author's counts are considered.

In the red cell counts a ‘crowding’ effect is noted by which the variance between the counts on the individual squares on the haemocytometer is reduced. This effect is trivial in white cell counting owing to the small proportion of the area occupied, but is important in reducing the variance between the numbers of red cells on individual small haemocytometer squares. A quadratic function adequately describes the regression of the variance on the mean for fixed size of haemocytometer square, for the usual range of red cell density. This function, calculated on the basis of the author's own counts also describes Berkson's findings on crowding adequately and is not, considering the approximations involved, inconsistent with the theoretical discussion on crowding. Reasons are given for believing that the crowding effect is only trivial if blocks of 16 squares are compared in red cell counting.

The methods of statistical control, suggested by R. A. Fisher's work, are introduced. It is shown that they give satisfactory results when applied to some of the author's own counts. The methods are used to discuss the consistency of the counts of certain medical graduates and technicians. The methods are suitable for a review of the literature with the object of examining the internal consistency of the counts made by various authors.
Damage to wheat by enclosed populations of Rattus norvegicus
Authors: Barnett S. A.
Published: May 2009

Small enclosed populations of the common brown rat (ten to twenty-six rats), each with access to one ton of sacked wheat for 12–28 weeks, caused a loss in weight of 4·4% of the wheat. 70·4% of the wheat was fouled and had to be cleaned before use. The main monetary loss was due to damage to sacks. Total monetary loss was 18·23% of the original value of the wheat and sacks.
The standardization of staphylococcal α-antitoxin, with special reference to anomalous haemolysins including δ-lysin
Authors: Marks J.
Published: May 2009

1. Evidence is submitted that an anomalous rabbit cell lysin reported by Minett (1936), α2-toxin and δ-haemolysin are identical. The last name is preferred.

2. Precautions are necessary to avoid interference by δ-haemolysin in titrations of α-toxin and α-antitoxin.

3. The existence of γ-haemolysin is confirmed; its wide distribution and possible confusion with α-toxin are noted. The name γ-toxin is thought more suitable than γ-hameolysin.

4. Multiple standard antisera are desirable for the detection of anomalous toxins. At least one should be of refined globulin.

5. Dilution and manipulation inactivate staphylococcal toxins and their effect needs consideiration in quantitative work. Infusion broth increases the stability of diluted α- and β-toxins.
Experiments on the food preferences of wild rats (Rattus norvegicusBerkenhout)
Authors: Barnett S. A. , Spencer Mary M.
Published: May 2009

1. Colonies of wildRattus norvegicusBerkenhout were kept in closed rooms containing nesting sites. The conditions permitted breeding.

2. Seventy-six experiments, each lasting 6–35 days, were done to test the rats' food preferences. In each experiment except two, a choice was given between two foods, both available in excess. In the two exceptional experiments a choice between three foods was given.

3. Although marked preferences were shown, a food was rarely quite rejected in favour of an alternative.

4. Among cereals, wholemeal was preferred to wheat grains, but wheat grains were preferred to white flour; little or no white flour was eaten if wholemeal was available. Wheat germ was eaten only in small quantities when an alternative cereal was available, but in larger quantities if the alternative was sugar or a sugar-cereal mixture.

5. The addition of sugar or saccharin to cereals increased acceptability; sugar was preferred to saccharin.

6. The addition of arachis oil to wholemeal or wheat increased acceptability.

7. Cod-liver oil at 2·4 % acted as a deterrent.

8. Total calorific intake remained steady over short periods, but over several weeks rose as the mass of the rat colony increased. The higher the mean weight of the rats in a colony, the lower the calorific intake per unit weight of rat.

9. The amount of food eaten was partly determined by its calorigenic capacity: in particular, wet foods were eaten in much larger quantities than dry foods.

10. The food preferences of wild rats differ in several respects from those of whiteRattus norvegicus.

11. Apart from palatability or flavour, the main factors influencing food preference were (a) previous experience and probably (b) the nutritional value of the food. The effect of previous experience was often observed when rats, accustomed to one food, gradually changed from the accustomed food to another. The stages of a change to a new food, or the establishment of a particular preference, varied, and are discussed in detail.
The effect of tuberculin on sensitized and normal leucocytes
Authors: Marks J. , James Dinah M.
Published: May 2009

It has been shown that the cells in exudates produced by the injection of tuberculin into the serous cavities of sensitized animals are alive and not dead as claimed previously. Such cells consumed oxygen and glucose at the same rate as cells obtained similarly from normal animals but moved somewhat less actively. Purified tuberculin had no specific effect on the respiration in vitro of macrophages or neutrophil leucocytes derived from sensitized animals.
Experiments on the Influence of Fatness on Susceptibility to Caisson Disease
Authors: Boycott A. E. , Damant G. C. C.
Published: May 2009

All seven series give answers in the same sense, and we may conclude that we have definite experimental evidence that fatness increases the susceptibility to death from caisson disease. The regularity of the results in the guinea-pig experiments suggests that fatness is here the predominant influence in individual susceptibility. The difference in weight between the “survived” and ‘died” is not always in the same sense, and is in no case very large. The weight factor may therefore be relatively excluded in considering these results : indirectly it is of influence in that rats, like men, tend to become fatter as they grow older. Our results show pretty clearly that females are fatter than males, and, in the guinea-pig series, much more susceptible. Femality, like age, is not a quality which can per se have any influence on susceptibility. The increased susceptibility of females is probably simply due to their increased fatness, which tends to further increase during pregnancy. With regard to symptoms other than death our evidence is very meagre. Some symptoms, e.g. bends, may be presumed to be independent of fatness.
Plague in Further India
Authors: Gimlette John D.
Published: May 2009

Further India has been affected by plague to a small extent in comparison to the Indian Empire. Some considerable interest therefore attaches to the comparatively unimportant local outbreaks which occur, from time to time, in the Malay Peninsula. It is generally very difficult to explain the reason for their limitation and to determine, with any degree of accuracy, the source of the infection. Kelanthan, a small but populous and fairly healthy Native Malay State, situated in geographical position between 4° 45′ and 6° 25′ lat. N., and 101° 30′ and 102° 40′ long. E., has only been exploited by European enterprise during the last seven or eight years. The State seems hitherto to have escaped from plague. The Kelantan Malays in fact, so late as 1905, looked upon plague as a new disease and, for want of a better name, then referred to it as the “penyakit leher” or “neck sickness.” Numerous deaths from this so-called “neck sickness” were reported by the natives of the interior to have occurred at some remote villages in the month of May 1905. The illness appeared from the clinical descriptions given by the Malays at the time to have been bubonic plague. It was not thought necessary however by the Kelantan Government to take any special precautions to prevent its spread, and the disease disappeared of its own accord in a few months' time.
Observations on the Evolution of Immunity in Disease
Authors: Noon L.
Published: May 2009

The following experiments constitute an attempt to follow out in detail the stages by which immunity is established, in the course of a generalised bacterial infection (Pseudotuberculosis of rabbits). Two aspects of immunity are considered, firstly the presence, in the circulating fluids, of specific antibacterial substances, and secondly the power of rapidly producing such substances in answer to the specific stimulus. That is to say, attention is directed, not only to the quantity of specific antibodies present on any day of the disease, but also to the response which the animal can make to various doses of bacterial vaccine. For the immune animal is both more vigorous and more sensitive than the normal, in its reaction to a renewed dose of poison (Wassermann and Citron, 1905). Naturally the facts established with regard to one disease only, cannot be predicated at once of other diseases, in other animals. Still it is hoped that the systematic study of one disease may give some help in coordinating the large but somewhat disjointed mass of clinical observation which is already available.
Immunity of Guinea-pigs to Diphtheria Toxin and its Effect upon the Offspring
Authors: Südmersen H. J. , Glenny A. T.
Published: May 2009

1. Diphtheria toxin-antitoxin mixtures induce a higher immunity in guinea-pigs than sub-lethal doses of toxin; one injection of the mixture being sufficient to produce an immunity lasting in some cases for a period of over two years, as shown by the passive immunity conferred on the offspring.

2. The highest immunity is produced by toxin-antitoxin mixtures containing the most uncombined toxoid.

3. The active immunity of the mother is transferred passively to the offspring.

4. The passive immunity thus transferred usually disappears at the end of two months after birth, and only in rare instances has been recongnised after three months.

5. Immunity is mainly transmitted in utero, and only to a slight extent during lactation.

6. Young bred from does that have been used for a single routine antitoxin test may be able to tolerate 14 times the does of diphtheria toxin fatal for a normal guinea-pig.
Purification of Water by Infusoria
Authors: Stokvis C. S. , Swellengrebel N. H.
Published: May 2009

Infusoria have the same bactericidal power as flagellates. Emulsions containing Bacillus typhosus, Vibrio cholerae, V. Dunbar, V. El Tor, B. megatherium and Spirillum volutans, to which Colpoda cucullus is added, are soon cleared. Before the clearage the Colpodae multiply actively.

This bactericidal effect does not depend upon the production of toxic substances by the Infusoria. The fluid obtained from filtered cultures of the Infusoria exerts no bactericidal effect. Only living Colpodae are able to clear the emulsions.

Direct sunlight does not prevent the clearing of the emulsions by the Infusoria, but temperatures below 10°C. and above 30°C. and absence of oxygen (anaerobic culture) are unfavourable to their exerting a bactericidal effect.

The polluted water of the canals of Amsterdam slightly delayed the clearage of the emulsions; the sewage of starch factories and gas factories completely prevented this clearage.

Consequently under natural conditions Infusoria will only play a part in purifying river water (1) if the temperature is above 10° and under 30°C., (2) if the aquatic vegetation is rich enough to supply the necessary quantity of oxygen, (3) if the water is not highly polluted by adjoining factories.
The Effects of Dosage in Typhoid Vaccination of Rabbits
Authors: Smith J. Henderson , Brooks Ralph St John
Published: May 2009

Following the subcutaneous injection of typhoid vaccine into rabbits the average antibody response was estimated from day to day, and found to vary for agglutination, bactericidal action, phagocytosis (including tropins), “precipitation” and probably for complement-fixation according to the dose of vaccine.

As estimated by the maximal value reached by the serum the response increases with increasing dose in nearly all cases. This increase becomes relatively less and less as the dose increases, and its progress suggests that with a sufficiently large dose a limiting-value might be reached, which if not actually a true limit would be practically one.

The observed relationship between dose and effect is such as to suggest that the combination of antigen and reacting-cell takes place in accordance with the rules governing adsorption processes; but this does not hold for the response in bactericidal power.

With increasing vaccine-dose the date at which the maximal value is reached gets later for the various antibodies, with again exception of the bactericidal power.

The precipitation observed differs from the usual precipitation reaction and is perhaps really an agglutination-phenomenon.

Phagocytosis was observed in three ways, and the bearing of the results on the mechanism of the action of the antibody concerned is considered; and the relationship between the bactericidal and other antibodies is also discussed.
The Photometry of Therapeutic Lamps I. Relation of Photo-electric Power of Lamps to their Bactericidal Power. II. Comparison of the Emission of various Ultra-violet Sources
Authors: Griffith Harry D. , Taylor John S.
Published: May 2009

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.
Paratyphoid Fever and Aertrycke Enteritis in Aberdeen—a Contrast
Authors: Bowie F. J. T. , Kinloch J. Parlane , Smith J.
Published: May 2009

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.