Specific precipitating antisera can be prepared in rabbits by the repeated inoculation of alum-precipitated serum.

High titre of sensitivity to the homologous serum is obtained only with a complete loss of specificity.

By absorption of the non-specific antiserum with heterologous sera the specificity can be restored.

Two types of reactions can be observed in such non-specific antisera: (1) the homologous reaction which occurs with the sera of closely related animals, and (2) the heterologous reaction which is attributed to the presence of antigens which are widespread among mammalian sera.

Cross-immunization experiments have demonstrated the presence of specific antigenic material in the serum of indvidual species.

A schematic representation of the antigenic arrangement of mammalian sera is suggested.

I am indebted to the Colonial Medical Research Committee for their help in this investigation and for the financial help provided by the Colonial Office.

I would like to acknowledge my indebtedness to Prof. P. A. Buxton, F.R.S., for his help and encouragement and in providing and housing the chimpanzee used in these experiments, to Dr C. H. N. Jackson and Mr W. A. Hilton for their valued help in the field in collecting a number of sera from East Africa, and also to Dr E. Hindle, F.R.S., for supplying me with materials from animals which had died at the Zoological Gardens, London. I wish to record my thanks to Mr E. Pope, for his valued technical assistance throughout these experiments.

1. A total of ninety-nine strains of anaerobic cocci from human beings have been studied and six groups demarcated on the basis of gas formation and fermentation reactions.

2.Gas formation by strains of group I is due to fermentation of glucose, laevu-lose or maltose, with a sulphur compound as an activator and with the production of gas rich in CO2.

3.Gas formation by strains of groups II, III and V is due to fermentation of different organic acids, sulphur not being required, and accompanied by the production of gases containing a high proportion of H2.

4.Two groups, IV and VI, do not from gas, but the latter has marked fermentation abilities.

There is correlation between microscopic apperances, probable pathogenicity, sensitivity to antibiotics and sulphonamides and the groups demarcated.

Ninety-two out of ninety-nine strains isolated from human beings could be placed in one or other group.

We are greatly indebted to Dr H. J. Parish of the Wellcome Research Laboratories for a sample of Polymyxin E, to Prof. L. Young for much assistance and advice and to those colleagues, particularly Dr R. M. Caiman of Queen Charlotte's Hospital, who sent us strains.

The routine methods for propagation of staphylococcal typing bacteriophages, and for their use in identifying strains of staphylococci, are described.

Most of the phages can be propagated in fluid media as well as on agar, and for some glucose-peptone-water is a better medium than nutrient or Todd-Hewitt broth.

Many phage filtrates derived from broth or agar propagation contain, in addition to the phage, an agent that inhibits the growth of staphylococci.

Investigations of variations in the routine typing technique showed that considerable latitude is permissible in the age of cultures used for typing and in the inoculation procedures. It is, however, important to test all phage filtrates after propagation for purity and freedom from the inhibitory agent; and to repeat the tests frequently during use to detect alterations in titre.

About 40% of staphylococci are not lysed by the phages used at their test dilution; about half of these untypable strains are lysed by undiluted phage filtrates.

An analysis was made of the results of typing 567 independent strains of staphylococci; 229 of these showed strong lysis by one or more phages, but there were no fewer than 82 distinct phage patterns represented, and only 118 strains were lysed strongly by a single phage. Certain phages tend to appear together in patterns and on the basis of such associations three main phage groups can be distinguished; they are known respectively as the ‘3A’, ‘6/47’ and ‘52’ groups.

No method was discovered for segregating patterns into ‘types’, but conventions have been devised on the basis of the variation observed in sets of strains from various sources, for distinguishing between different patterns.

We are deeply indebted to Dr V. D. Allison for teaching us the bacteriophage typing methods and for giving us the benefit of his wide experience.

We are grateful to the following for sending us phages, and in some cases discussing their results with us: Dr Phyllis Rountree, Sydney; Dr R. Wahl, Paris; Dr G. Wallmark, Stockholm; Dr H. Williams Smith, Poultry Research Station, and Mr A. M. Hood, Birmingham.

Our thanks are also due to Miss S. Mayo, Mrs E. Lyons and Mr D. Woodroof for technical assistance. The photographs for PI. 14 were taken by Mr W. Clifford.

1. ACTH, cortisone, sphingomyelin and sphingosine produce a delayed in-hibition of the skin reaction in cattle sensitized to Trichomonas foetus antigen when they are injected intramuscularly. The inhibition is greatest 6–9 hr. after injection of the inhibitor, but may sometimes be further delayed. This reaction is associated with an absolute lymphopoenia of slightly variable duration.

N-acetylsphingosine retains the desensitizing effect of crude sphingomyelin and is of much the same potency as cortisone acetate of Merck.

2. The lymphopoenia associated with the injection of ACTH and cortisone occurs also with sphingosine, and these three substances are also alike in not producing the desensitizing effect until some hours after the injection.

3. Phenergan, a synthetic anti-histamine, has a different action, and its desensitizing effect which appears to depend on a direct antagonizing of the oedema-provoking substance resulting from the junction of antibody and antigen (hapten) takes effect apparently as soon as the injected drug itself is present at the site of the injection of the specific testing fluid.

4. Methods of testing the capacity of the hormones and drugs to prevent the skin reaction locally and to nullify the action of the in vitro antigen-antibody mixtures which can produce a reaction in normal animals are described.

Phenergan alone of the substances dealt with has any power to act locally. Phenergan mixed with the antigen-antiserum complex in vitro prevents the formation of the characteristic swelling in a normal animal.

Phenergan mixed with the specific testing fluid prevents the development of the skin reaction when the mixture is injected intradermally into a sensitive animal.

Cortisone and sphingosine do not have this action.

We are indebted to the Medical Research Council for supplies of ACTH and cortisone and to Sir Charles Harington for N-acetylsphingosine.

The personal encouragement of Prof. H. G. Lamont and the support afforded by the Ministry of Agriculture, Northern Ireland, are gratefully acknowledged.

Comparable groups of adult African women were vaccinated (a) with a mixed 17 D yellow fever-vaccinia vaccine administered by scarification, or (b) by inoculation subcutaneously with 17 D vaccine followed by scarification with vaccinia vaccine. There was no significant difference in the response of the two groups to the vaccinia vaccine. In the group inoculated with the mixed vaccine, of those whose sera contained no demonstrable yellow fever antibody prior to vaccination, 66·6% had developed antibody when their sera were tested 28 days later. In the other group 100% had developed antibody by the twenty-eighth day after vaccination.

It is suggested that the difference in the response of the groups in this study might be due to some local interference which prevented invasion by the 17D virus in some cases.

While there is good evidence for the efficiency of 17D vaccine as an immunizing agent when administered by scarification (Hahn, 1951; Dick, 1952), the present study indicates that the percentage of those who became immune after vaccination with the mixed vaccine used in this trial is not sufficiently high to suggest that this type of mixed vaccine should be used routinely.

In none of our patients was any reaction noted to the mixed or double vaccinations. Further information is required on the reaction of both negro and white races to combined vaccinations with yellow fever and vaccinia viruses. It is suggested that a careful follow-up of persons vaccinated by the combined Dakar vaccine might produce some valuable information in this respect.

Our thanks are due to Dr George Campbell Young for his very great co-operation, and to Messrs W. A. Whittaker, L. E. Hewitt and D. Santos for technical assistance.

A Factor Analysis has been made of the co-variation between the mortality rates from cancer of ten male body sites and of eight female body sites, in thirty large towns in England and Wales from 1921 to 1930. The method of analysis adopted is Hotelling's method of Principal Components.

Four male and four female Factors are obtained, which together account for approximately three-quarters of the total variance.

A Factor is found to be associated with cancer of the larynx, oesophagus, stomach and tongue in men and with cancer of the stomach and negatively with cancer of the breast and ovaries in women. In both sexes, the Factors are associated with an index of adverse social conditions.

Another Factor is found to be associated with cancer of the rectum and bladder in men and this Factor is associated with good social conditions.

A special Factor associated with cancer of the colon is unrelated to the mortality from cancer of other sites, save that in women it is negatively associated with cancer of the rectum.

A Factor for cancer of the lung in men is unrelated to cancer of the larynx, and is inversely related to cancer of the tongue.

We are most grateful to Dr Percy Stocks, late of the General Register Office, and to Dr W. P. D. Logan, Chief Medical Statistician of the General Register Office, for their help in providing us with the relevant basic material; and to Miss E. M. Hines, Miss A. H. Huntley and Miss M. Rogers for assistance in the calculations.

1. It has been found possible to detect traces of the virus of foot-and-mouth disease in mixtures of this virus and that of vesicular stomatitis by cross-immunity tests in cattle. A quantity of the virus of foot-and-mouth disease as small as 1·3 I.D. 50 was revealed by the inoculation of such mixtures into cattle immune to vesicular stomatitis.

2. It is suggested that such a method would be useful in the analysis of possible mixed infections in field outbreaks.

3. The usefulness of complement-fixation tests to confirm the resolution of mixtures has been demonstrated.

The author wishes to thank the Director of this Institute, Dr I. A. Galloway, for his advice and encouragement. The technical assistance of Messrs E. Scoates and P. M. Mitchell is also gratefully acknowledged.

Twenty-four selected strains of Pseudomonas aeruginosa have been classified on the results of precipitin tests with trichloracetic acid extracts into six serological groups.

This differentiation was confirmed by O agglutination.

Four of the six serological groups can be further subdivided according to their sensitivity to one or more of nine phages.

Alcohol treatment reduces agglutinability of some strains, particularly if alcohol is added to very concentrated suspensions of bacteria in the preparation of O suspensions.

The precipitation method has been applied to eighty successive strains of Ps. aeruginosa isolated, and with the available sera seventy-two could be placed into one or other of the six serological groups.

I am grateful to Mr G. S. Turner and Miss D. L. Deeks for their able and enthusiastic assistance in this work, and to all the members of my staff for their constant helpful co-operation.

The Virus Research Unit was in receipt of additional financial assistance from the Nkana-Kitwe and Chingola Poliomyelitis research funds.

Naval ratings serving in a warship in the tropics answered a questionnaire concerning their sensations of warmth at meal times on the mess-decks during two investigations carried out at an interval of 6 months when the ship was proceeding between tropical and more northerly waters. Temperature measurements were recorded at the same times as the questionnaires were completed by the subjects.

It is proposed that the upper level of warmth to be accepted in the design of ventilation systems for accommodation spaces should be those conditions when either more than 80% of persons feel reasonably comfortable or less than 20% observe the presence of unevaporated sweat on their skin, which corresponds to effective temperatures of 79 and 78° F. respectively, according to the majority opinion in these two investigations. The latter figure of 78° F. is suggested as the upper level to be accepted for men living under these conditions.

The upper level of the optimum or ideal zone for comfort, when equal proportions of persons reported that they were either cool or warm, was observed to be at 74° F. effective temperature.

The proportions of men who were uncomfortably warm at different levels of warmth were related to the proportions who reported that their skin was wet with unevaporated sweat. Very few observed that they were sweating, whatever the air velocity or their clothing, when the dry-bulb temperature was below 83° F., and the wet-bulb temperature below 75° F.

Brisk circulation of the air on the mess-decks made an increasingly large contribution to the comfort of these very lightly clad men as the air temperature rose from 85 to 89° F., but as the temperature fell below 83° F. variations in air Thermal comfort in the tropics 431 movement had little effect on the proportions of persons who were reasonably comfortable under these warm conditions.

Thermal discomfort was reported by an increasing number of men within a temperature zone where others have shown by experiment that there will occur a statistically significant decrease in the skilled performance of men who are acclimatized to working at high temperatures.

This paper is published by the permission of the Admiralty and the Medical Research Council's Royal Naval Personnel Research Committee. The investigations described were made possible by the active interest of Captain H. S. Hopkins, C.B.E., Royal Navy, and Commander W. Elliot, D.S.C., Royal Navy, the excellent facilities which they placed at the disposal of the observers, and the wholehearted co-operation of the naval ratings who acted as subjects. I am indebted to Dr T Bedford for advice and criticism and to Mr Cheng Swee Guan and Sick Berth Attendant W. F. Montague, Royal Navy, for care in tabulating the data, preparing the illustrations and technical assistance.