1. A series of 62 nasal carriers of B. diphtheriae, virulent and avirulent, has been investigated.

2. Treatment by means of normal saline gargles and sniffing normal saline up both nostrils appeared to reduce the number of positive swabs by two, but the data are not quite decisive on this point.

3. With the above treatment the majority of the patients were carriers for periods of less than 9 days.

4. Two successive negative swabs were followed by positive results in 22 cases.

5. In order to recognise 99 per cent, of the carriers in a population receiving treatment with normal saline, five swabs are required from each person examined.

6. Equations are given by which the expected length of run may be calculated for other conditions.

1. A consecutive series of 400 cases of diphtheria from the Romford (Essex) area have been bacteriologically typed and correlated with the clinical findings.

2. Gravis infection was found to be the most prevalent type.

3. The intermedius type was the most lethal and severe.

4. Mitis infection formed the smallest proportion of cases, usually of a mild character.

5. Laryngeal cases were few, and all three bacteriological types were represented.

6. A large proportion of children of 7 years and over were attacked.

1. 1614 strains of Corynebacterium diphtheriae have been typed and analysed and some anomalous varieties described.

2. The various types have been considered in their relation to case severity.

3. Some comments are offered on the colonial and biochemical characteristics of the various types of C. diphtheriae

4. and on the serology of the strains found in Glasgow.

5. Two gravis-like strains Types IV and VI have been observed and correlated with clinical findings, and their cultural and biochemical characteristics described.

6. Attempt has been made to confirm alleged change in fermentative characteristics by growth in serum broth, with negative results.

In this paper the pathological and the bacteriological findings in ten instances of naturally acquired tuberculosis in ten different species of animals are recorded. The tubercle bacilli obtained in culture from five species (bat, bear, bison, hedgehog and mink), all cases of fatal tuberculosis, were of the bovine type. The bacilli from a case of localised glandular tuberculosis in a goat and one of tuberculosis of the pancreas in a kangaroo were of the avian type. The bacilli from a case of generalised retrogressive tuberculosis in a horse, of minimal thoracic tuberculosis in a calf and cutaneous and glandular tuberculosis in a parrot were of the human type. These results amplify the evidence already published which shows that each of the three types of tubercle bacilli (bovine, human and avian) is able to cause natural tuberculosis in many different species of animals other than that which is its normal habitat.

The bovine bacillus which is transmitted to animals almost exclusively by tuberculous bovines is responsible for the greater part, especially the generalised and fatal forms, of the tuberculous disease occurring naturally in farm and domestic mammals and for a not inconsiderable amount of tuberculosis in human beings.

The avian bacillus whose natural host is the domestic fowl can infect casually many species of mammals, namely the pig, the ox, the sheep, the goat, the horse, the guinea-pig and the rabbit and in Zoological Gardens several marsupial species. Instances of its transmission to the different species of farm mammals are rare, except in the case of the pig, and the disease produced is usually limited and confined to the glands adjacent to the points of entry of the bacilli. This type of bacillus may however cause severe generalised and fatal disease in the pig, sheep, rabbit and marsupials.

The human bacillus has a narrower range of pathogenicity than either the bovine or the avian bacillus. This type can infect the pig, the calf and the horse, but does not produce progressive tuberculosis in these species. It causes cutaneous tuberculosis in parrots and is one cause of tuberculosis in the dog and in various species of animals kept in captivity, namely the guinea-pig, monkey, gnu, antelope, peccary, etc., in which species infection is followed by generalisation and progression of the disease.

The evidence accumulated regarding the susceptibility of various species of animals to the three types of tubercle bacilli under farm and domestic conditions and in captivity may be summed up as follows.

All three types of bacilli can infect the ox, pig, horse, guinea-pig and rabbit.

Two types of bacilli have been found in the following species; viz. bovine and avian in the sheep, the goat and Australian marsupials; bovine and human in the domestic dog and in the ape, monkey and Ungulata in captivity; human and avian in the parrot.

Only one type of bacillus has so far been obtained from domestic fowls (the avian), the domestic cat, hedgehog, mink and ferret (the bovine) and members of several species in captivity.

The use of 1 per cent, milk agar gives a significant increase in colony numbers for both raw milk and pasteurised milk at all levels of count. There is a marked increase with pasteurised milk on the 1/100 and 1/1000 plates. Milk agar also gives better colony growth, tending to more rapid and accurate counting. With raw milk there is no correlation between the increase and the count on standard agar.

1. Groups of young rats have been fed for periods up to one year on a diet consisting of raw or sterilized milk, with a biscuit made from white flour, to which were added supplements of iron, copper and manganese salts. By this method two samples of commercially sterilized milks, prepared by two different processes, have been compared with the corresponding raw milks drawn from the same bulk supplies.

2. At the end of one year the weights of the groups receiving sterilized milks were about 10 per cent, lower than those of the animals receiving raw milks from the same bulk supplies. This finding is similar to that of Drummond (1933) in a study of the relative values of raw and pasteurized milks by the same methods. It is however in considerable contrast to that of Mattick and Golding (1931) who in comparable experiments found that sterilized milk did not adequately support growth.

3. Animals receiving sterilized milks remained in excellent condition throughout the experiment and they could not be differentiated as regards general health from those which received the raw milks.

4. Adequate reproduction occurred on the raw milks, but no litters were reared. Reproduction was less good on the sterilized milks and, as with the raw milks, no litters were reared.

5. The results with the milk prepared by one sterilization process seemed on the whole better than those from the other; but the evidence was not sufficiently conclusive to make this deduction certain.

1. Some improvements in the determination of small quantities of iodine in biological substances are described.

2. The thesis that a low iodine intake is prerequisite for goitre production is supported.

3. A survey of determinations by various authors of the daily urinary iodine excretion in goitrous and non-goitrous regions leads to the conclusion that the critical level of iodine intake sufficient to suppress goitre is between 120 and 160γ per day.

4. Determinations of urinary iodine excretion in New Zealand and in the non-goitrous islands of Samoa are presented which show that in the parts of New Zealand investigated the iodine intake is at a low or goitrous level.

5. The result in New Plymouth, Taranaki, shows that a high content of iodine in the soil does not necessarily assure an adequate iodine intake.

6. The progress of prophylaxis by iodised salt in New Zealand is reviewed, and from consumption data it is concluded that iodised salt constitutes approximately only 30 per cent, of the domestic salt consumption of New Zealand.

7. To ensure a more general use of iodised salt it is recommended that the regulations be amended to provide that:

(a) Ordinary domestic salt shall be iodised.

(b) Non-iodised salt shall be sold only in packages labelled “Non-iodised” and with the addition “ The use of this salt exposes the user to the risk of developing goitre”.

8. The results obtained hitherto with the use of iodised salt are briefly reviewed and attention drawn to some apparent failures even when iodised salt has been used for all domestic purposes. These failures are attributed to the standard for iodised salt being too low.

9. It is concluded that for New Zealand a supplementation of at least 100γ per day is necessary to afford complete protection against goitre.

10. To provide the necessary amount of supplementation the iodine content of iodised salt in New Zealand requires to be raised. We recommend therefore that either

(a) If the domestic salt only is to be iodised the standard be fixed at from 5 to 6 parts of potassium iodide (KI) per 250,000 of salt, or

(b) If iodised salt is to be used in the manufacture of bread, butter, bacon and other salted foods, the standard be fixed at from 3 to 4 parts of potassium iodide (KI) per 250,000 of salt.

11. In New Zealand cabbage has not shown any marked goitrogenic activity as tested on rabbits.

12. Turnip roots showed sporadically a goitrogenic activity comparable with that found for the most active samples of cabbage in other countries.

13. In tests of Brassica seeds on rats, goitrogenic activity was found in rape seed, cabbage seed, steamed white mustard seed, and steamed black mustard seed.

14. The activity of rape seed was destroyed by steaming.

We have pleasure in acknowledging the financial help which we have received from the Sir John Roberts Endowment for Medical Research, from the Sir H. L. Ferguson Fund and from the Honorary Staff of the Dunedin Hospital, and for the co-operation of a large number of our colleagues in New Zealand and Samoa in the collection of specimens.

A survey has been made of the different theories put forth to explain the nature of ultra-microscopic viruses, and it has been concluded as probable that they are representatives of some precellular forms of life. The writer's views have been given, and the probabilities have been expounded regarding the constitution of these forms, their evolution towards a composite cell, the conditions under which they exist, the means by which they obtain the necessary energy for their vital processes, and their food requirements. It has been suggested that at times some unit of a cell may undergo a partial or complete reversion to the independent precellular form. The possibility of the existence of other primitive forms of life, belonging to another biological world, has also been considered. The theories discussed have been analysed in relation to the known facts concerning virus diseases, transmissible bacteriolysis and cancers.

The reorganisation of the laboratories and the fitting up of various electrical and timing equipment, which were necessary to test the theories experimentally, have been explained, and a description has been given of some of the special pieces of apparatus made in the workshop for the experiments.

Experiments were carried out on an extensive scale with animal and vegetable materials containing known viruses, with muds, etc., presumed to contain precellular forms of life, and with bacteriolytic agents. Certain delicate bacteria, isolated from porcelain filtrates, were used as controls.

Attention was first given to indicators for growth, and it was found that minute quantities of selenium oxychloride incorporated in media resulted in many bacteria growing with a bright red colour.

From an extensive series of experiments on nutritive requirements, it was determined that beef extracts usually act detrimentally on bacteria, and they should not be used. The detrimental effect was marked with the bacteriolytic agents. Good agar media were gradually evolved. Rain water proved to be better than water from a town supply. A watery extract from certain clays supplied sufficient nourishment for many bacteria, but the media were improved by the addition of watery extracts of bracken ash and of the fronds of certain ferns, notably those belonging to the Asplenium group.

The associated conditions used during cultivation were varied in many ways, particular attention being given to the influence of solar rays and the energy emitted from projector lamps. In different experiments the wave energy was modified by reflection or filtration, different bands being tested both consecutively and intermittently. The materials used consisted of lenses, prisms, natural rocks and crystals, as well as animal, vegetable and chemical filters.

Many bacteria were found to tolerate solar rays when cultivations were made on suitable media, particularly if the action was intermittent. They were least tolerant to the region of the spectrum around 4000 Å.

A spore-bearing bacillus has been obtained from cultures of a mud nitrate on a leaf mould extract medium, placed under the intermittent influence of filtered solar rays. A group of the colonies developed a homogeneous waxy change, which was proved to be associated with a dissolution of the spores. It is suggested that the change is due to the presence of a “sporolytic agent”, although it has not been found possible to demonstrate the agent in a porcelain filtrate.

In a number of cases pleomorphic bacilli have been cultivated from old porcelain filtrates obtained from various diseased plants and muds. Many were found to be very sensitive as to their nutritive requirements. Most of them grew well in subdued daylight and under the influence of a 100-watt projector lamp.

Other porcelain filtrates produced granules on the surface of certain experimental media. When subcultures were made, granules associated with a marked milky opalescence of the medium occurred along the line of inoculation. No bacterium could be found in films made from the granules. The phenomenon appeared only on tubes of media which were autoclaved, set and inoculated on the same day. The milky opalescence can be produced without the presence of an unheated filtrate. The significance of the granules is being investigated.

Many comparative experiments have been carried out with suspensions of dead micrococci, either uninoculated or inoculated with living micrococci or a bacteriolytic agent or with both. It has been shown that suspensions of dead bacteria undergo more marked clearing when placed under the influence of solar or other rays than when placed in darkness. The effect is increased when the suspensions are prepared from cultures grown on tubes of media which have been autoclaved, set and inoculated on the same day, and it is particularly marked when the suspensions have been inoculated with living micrococci. The significance of these and other results has been considered, and attention has been called to the utilisation of the factors concerned for the purpose of freeing intracellular toxins in the preparation of various vaccines.

In conclusion I should like to record my appreciation of the valuable services rendered by my only assistant, Mr H. Frankham, the laboratory attendant and caretaker of the Institution.

The death certificates for cancer of the lung and of the larynx in males from England and Wales for the years 1921–32 inclusive, numbering 18,280, have been investigated.

Sources of error in statistical work on death certificates are discussed.

Latterly autopsies have been made upon about 28 per cent, of cases of cancer of the lung, and 9 per cent, of cases of cancer of the larynx. The increase in the recorded cases of lung cancer is not nearly accounted for by the increase of data obtained by autopsy.

The agricultural and coal-mining industries show a low incidence of cancer of the lung and of the larynx.

The factors which lead to silicosis appear not to be very active in producing cancer of the lung or larynx, but in metal grinders the incidence of cancer of the lung is 2¼ times that in the general population. A group of open-air occupations, where there is exposure to the dust of roads, have rather high ratios for cancer of the lung and of the larynx with the exception that motor drivers have a normal liability to cancer of the larynx. On the whole, no occupation involving exposure to any kind of dust has been found in which there is any very high incidence of cancer of the lung or larynx. Cases of cancer of the lung in asbestos workers are described in recent literature, but none has been found among the certificates considered here (up to 1932).

Workers exposed to coal gas and tar, and those engaged in the preparation and sale of tobacco, tend to show an increased prevalence of cancer of the lung.

Occupations concerned with the supply of alcohol have a high incidence of cancer of the larynx.

To investigate the occupational incidence of cancer thoroughly one should have before one, simultaneously, comparable figures for cancer of all parts of the body which could be effected by an external agent.

With regard to the view, that the recent rapid increase in recorded deaths from cancer of the lung is due to the detection of more cases by improved diagnosis, the very moderate ratio (129) for cancer of the lung in medical men is noteworthy, for this is an occupation where the availability of the existing methods for the detection of cancer is presumably at a maximum.

Data are given of the prevalence of cancer of the lung and larynx in men and in women, and of the rate of increase in the two sexes in recent years. The greater incidence of cancer of the lung upon men than upon women is discussed. The recent rate of increase of cancer of the lung in men is found to be not much greater than that in women, when these increases are reckoned in percentages.

The increase in recorded cases of cancer of the lung may be due to (1) an actual increase; (2) improvement in diagnosis; (3) fashion in diagnosis; or to any combination of these factors. A comparison is made between the increase of cancer of the lung, and of cancer of the prostate; the number of deaths attributed to cancer of the prostate appears to have reached a steady level.

No special occupations have been found to which the increase in the total of cases of cancer of the lung can be attributed; rural workers show an increase which is not much less than that in the general population.

No evidence has been found that tarring of roads has affected the incidence of cancer of the lung upon the general population. Such data as are available suggest that coal tar in the atmosphere, whether derived from roads, domestic chimneys, or any other source, does not readily give rise to cancer of the lung. Cotton-mule spinners show an especially small liability to cancer of the lung although they inhale air sprayed with an oil which produces cancer of the skin.

Improvements in diagnosis must have led to the detection of a larger proportion of the existing cases of cancer of the lung; whether there has been an actual increase in these cases cannot be decided from the data presented here, but a source of evidence on this question is suggested.

We are indebted to the Registrar-General for the data considered in this paper, and also for kindly permitting us to use some figures which have not yet been officially made public. We have received much assistance in the classification of occupations from some members of the Staff of the General Register Office, to whom we wish to express our gratitude. We wish to thank also Dr J. C. Bridge, Senior Medical Inspector of Factories, for information upon various matters, and especially upon silicosis. We are greatly indebted to Miss L. D. Henderson for much assistance in carrying out the calculations.