The result of bacteriological research indicates that the material infected is probably not large compared to the total amount used, and that in suspected samples of both hair and bristles anthrax bacilli can be isolated either by inoculation of animals or by plate cultivation.

Difficulties are met with in the inoculation of animals owing to the presence of the bacillus of malignant oedema, which, unless special methods are used as shown by Duncan, will often mask the presence of the anthrax bacillus altogether.

In separation by means of agar plates the presence of bacilli very closely resembling anthrax again leads to error. Three types of these bacilli have been met with in hair and bristles; viz.: Bac. A2 or Bac. anthracoides of Bainbridge, possibly the same as Bac. subtilis, the Bac. A1, and Bac. A. The last two do not exactly correspond with any known bacilli, and so far as we know at present are of little importance, but in view of the experiments of Gilruth showing that guinea-pigs, rabbits, and sheep can resist the inoculation of large doses of virulent anthrax bacilli completely, provided these organisms are mixed with a larger quantity of some other organisms which are non-pathogenic to these animals, and that a small amount of immunity to pure anthrax is conferred, it is certain that the presence of these anthrax-like bacilli, evidently closely related to the anthrax bacillus, cannot but be of benefit; and it is possible that further experiments may show that injections of them mixed with cultures of anthrax bacilli of varied virulence may confer a higher degree of immunity than do mixtures of anthrax with other non-pathogenic bacilli, as shown by Gilruth (1904).

In July 1906 attention was drawn to the fact that a large number of tinned foods returned from the South African campaign were exposed for sale on the home markets. The majority of these foods were known to have been from five to seven years in tins, and the possession of this material afforded a rare opportunity for investigating the question of metallic contamination, and for determining how far such contamination was deleterious to the public health.

All observers agree that Musca domestica comprises over 90 percent. of the flies found in houses; my own observations show 97 percent. M. domestica is most easily distinguished by the venation of its wings, the fourth vein being bent up at an angle, and by the four longitudinal black stripes on the thorax. It is thus easily distinguished from Homolomyia canicularis, another somewhat smaller fly which frequents houses and forms the bulk of the remaining 3—10 per cent.

The plague suppressive campaign which is now drawing to a close in San Francisco has been conducted almost entirely on the principle that the great factor in the spread and continuance of the disease is the rat. The fact that the epidemic among human beings ceased within four months after the beginning of active operations and that in spite of the distribution of the disease in almost every quarter of the city, only one hundred and fifty-nine cases, with seventy-seven deaths occurred, proves the wisdom of this policy. The campaign has been conducted by the United States Public Health and Marine Hospital Service.

In determining the fermentative powers of this organism both fluid and solid cultures were used. The fluid medium was made up according to the formula employed by Dr M. H. Gordon. It consisted of Lemco ·1 gram, peptone ·1 gram, sodium bicarbonate ·1 gram, 10 per cent. watery solution of litmus 10 c.c., water to 100 c.c. This medium was sterilized by heating under pressure and to it was then added the substance to be investigated in the proportion of 1 per cent. Subsequent sterilisation was effected by heating in the steamer for 10 minutes on three successive days. In the case of laevulose, arabinose, and xylose the flasks were heated over the Bunsen flame, as in the steamer the medium turned red.

1. A larger dose of toxin is necessary to kill a guinea-pig of the same weight in summer than in winter.

2. The rate of growth of guinea-pigs is more rapid in the summer months.

3. The weights of guinea-pigs are least affected by lethal doses in summer.

4. For guinea-pigs of the same weight the fatal dose increases with the age.

Ankylostomiasis was first discovered in men working in Cornish mines in October, 1902 (this Journal, Vol. III. p. 95), though there had been many cases of illness clearly referable to this cause for some eight years previously. The number of men who were too ill to do their ordinary work was greater about two years before the cause of “Dolcoath anaemia” was identified. These men had either stopped at home or had been employed on the surface instead of underground: in this way they had avoided further infections, and in many cases had progressed towards a spontaneous cure. At the time therefore of our first enquiry the number of sick men was less than it had been. Anaemic miners were, however, still very numerous and, without anything like an exhaustive search among the 750 underground hands at Dolcoath mine, we found 14 men with less than 50 p.c. haemoglobin and 19 more with less than 75 p.c. The general pallor prevalent among the men on looking at a shift as a whole was very striking, and complaints of shortness of breath on climbing the ladders were frequent. The disease, in short, was at that time a meterial hindrance in carrying on the work of the mine.

A case recently tried before Mr Justice Warrington (The Flour Oxidising Co., Ld. v. J. and R. Hutchinson) has brought to light, what I do not imagine is a matter of common knowledge, namely that large quantities of flour both in this country and abroad are artificially bleached in order it would appear primarily to satisfy the fancy of the public for white bread. The popular taste for the appearance of their food naturally leads the caterers to satisfy it; the yellowness of milk and its richness are usually associated together in the mind of the man in the street consequently it is very difficult now-a-days to purchase milk which has not been artificially coloured.

The practice of using preservatives in the process of making cider is very widely spread, and moreover is much encouraged by the makers of the preservatives.

We are still in doubt regarding the exact position of those bacilli which, morphologically and culturally, appear to be identical with the Klebs-Loeffler bacillus but which differ from it only in the absence of specific pathogenic power for laboratory animals. Most writers regard such non-virulent strains as true diphtheria bacilli which have lost their virulence and toxigenic power either temporarily or permanently. Others however are inclined to place them in a group allied to that of the genuine Klebs-Loeffler bacillus and express doubts as to whether they at any time possessed a claim to pathological significance (Graham Smith, 1904).

That cellular elements are found normally in milk has been known for many years, but it is only comparatively recently that any importance from a public health point of view has been attached to their presence. These cellular elements being usually regarded as leucocytes or pus cells, it is natural that their occurrence in milk should be looked on as indicative of an inflammatory process in the udder of the cow or cows from which the milk was obtained. The first observers to make any attempt to arrive at the numbers of these cells in milk seem to be Stokes and Wegefarth (1) in 1897. Their method, however, was very crude, and is not suited for making a true enumeration. Stewart (2) and Slack (3) followed with a very similar method, except that special tubes were used for obtaining the deposit. This “smeared sediment method” as it is called, is, however, capable of great inexactitude. Later observers have, by the use of ordinary blood counters, made the counting of the cells in milk a scientific measurement of reasonable accuracy. To Doane and Buckley (4) belongs the credit for the first published use of such a method. Savage (5) however has made the process still more accurate by first diluting the milk before centrifugalisation, and also by counting all over the field of the blood chamber, two innovations which are of very great importance, as has been borne out by our investigations. Error is easily introduced if counting is confined to the ruled divisions of the counter. Recently, Trommsdorff 6 has used a methodbased on the measurement of the deposit obtained on rotation in agraduated tube, and this method, probably on account of its ease and speed, has found much favour in Germany. It has been severely criticised by several investigators, such as Schuppius 7 and one of us 8. Riihm 9 and some others believe that it is useful if used as a routine control method. We are of opinion that it might be used in such away as an “indicator,” but for the purposes of public health control it isquite hopeless.

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.

(1) At present no public authority possesses legal power to deal with the question of the contamination of shellfish.

(2) It is not sufficient to test shellfish exposed for sale in a market or shop. These may have been contaminated subsequent to removal from the fishery; and multiplication of the contained bacteria may have taken place. The results of such analyses may lead to unjustifiable condemnation of a laying. It is essential that a topographical examination should be made and that samples for analysis should be taken from the laying itself.

(3) In the case of natural shellfish beds there is so much variability in the conditions with regard to the susceptiblity to pollution that a fairly large number of the animals must be examined. The labour of the analyses is therefore so great that the development of some simple routine test for faecal contamination is most desirable. Since most desirable. Since most natural shellfish layings are situated within the “sewage zone”, and therefore contain B. coli, quantitative results are essential.

(4) There are considerable differences in practial routine work in regard to the methods of isolation of intestinal organisms from shellfish; and aslo with respect to the number and nature of the reactions necessary for the identification of B. coli. It is desirable that some generally recognised series of tests should be uniformly adopted by bacteriologists engaged in such work. Further, different micro-organisms, possibly of varying degrees of significance as indicators of faecal contamination, may have been confused. There is possibly some variation in cultural characters in B. coli, and investigation of this variability is desirable. Investigation of the changes in cultural reactions undergone by intestinal organisms when entering the sea, or the tissues of marine shellfish, is also very desirable.

(5) Remedial measures other than the simple closure of a contaminated laying might be suggested. It is possible to subject the shellfish to treatment which will cause them to clean themselves of contained sewage bacteria. The source of the pollution may be removed; and sterilisation of the shellfish may be practised.

It is generally conceded that there is no one circumstance associated with occupation which has a more baneful influence upon health than the protracted inhalation of dust.

At the commencement of this paper it was pointed out that anthrax has been associated with the manipulation of hair and other raw animal materials for at least a century and a half, but that it has only been studies from an industrial point of view during the last 30 years, with the result that in 1895 cases of anthrax, occurring in workshops and factories, became notifiable. From that time to the end of 1907, over 500 cases have been brought to the notice of the Home Office. Beside these cases of industrial anthrax many others arise, chiefly from contact with animals or animal carcases affected with anthrax; these are not notifiable in this country.

The proportion of industrial to non-industrial cases of anthrax is about 4 to 3.

An analysis of cases of anthrax notified between 1898 and 1907 shows:

(1) A progressive increase in the number of cases in the woollen and worsted-industries, probably due to the increased use of dangerous classes of wool.

(2) A progressive increase in the rate of mortality, due to the larger number of internal cases among manipulators of wool.

(3) A lower rate of mortality among workers on horsehair and bristles than in other industries.

(4) A high rate of mortality in the group of miscellaneous industries in which anthrax is not usually suspected, the diagnosis being then made too late for effective treatment.

In order to make an early diagnosis it is essential for anthrax to be suspected from the nature of the employment.

Among bristle and horsehair workers:

(1) Anthrax is more fatal to the women than to the men.

(2) The occupational risk is greater for the men than for the women, because the former are more often employed in the earlier, more dangerous manipulations.

(3) The occupational risk is greater and the mortality higher among the manipulators of horsehair than in brushmaking.

(4) Horsehair is from 8 to 10 times as likely to give risk to cases of anthrax as are bristles, and the risk of infection is greatest from Chinese, Russian and Siberian raw materials; this is confirmed by actual experience not only in this country but abroad.

(5) The risk to workers on horsehair is greater than the risk to workers on wool.

The nature of the lesion varies considerably with the industry, inhalation of spores being uncommon in any but the woollen industry, though internal cases undoubtedly occur among horsehair manipulators. This is not surprising as many of the processes in these industries are similar.

The position of the pustule varies slightly with the occupation; for example, pustules on the neck are most frequent among hide and skin workers, due to the frequent carrying of skins on the shoulder. Malignant pustule is most common on the exposed parts, and to the latter those less frequently washed, as the neck and face. The infection is in most cases by the nails, which harbour the dust containing anthrax spores.

In agricultural cases lesions on the upper extremity are most common.

The mortality varies with the situation. Difficulty of operation, frequent absence of the diagnostic signs of local necrosis, looseness of the cellular tissues increase the mortality.

In all countries except Great Britain agricultural anthrax is the most common, and consequently there is a close relation between the number of cases of human and animal anthrax.

Variations in the prevalence and mortality of anthrax among human beings occur in different countries, and may to some extent be accounted for by natural constitution and environment.

There has been a progressive increase of cases in Italy, but a decrease of the death-rate, roughly corresponding to the introduction of Sclavo's serum treatment.

French statistics, as do the English, emphasize the greater risk to horsehair workers, though the risk and mortality in Great Britain compare very favourably with those in Franch, and still more so with those in Germany.

The danger of infection from anthrax in the manipulations of animal hair and bristles depends on the origin, king and cleanliness of the materials, and the processes they have to undergo.

Bristles as imported vary immensely, some being well cleansed and prepared, others in an extremely dirty state, but they are always in a far more prepared state than the horsehair.

The long tail horsehair, being more valuable, is better cleansed and less likely to cause infection than the shorter mane horsehair.

Cases of anthrax occur in practically all the processes to which hair is subjected from its time of arrival even to the finished products. Further, incidence is greatest among workers in short hair as brush-makers, and in the earlier processes, i.e. when the hair is in a less prepared state.

Infection may be carried in clothes or nails to people outside by workers.

Anthrax spores may retain their vitality for years on hair and other materials.

The dangerous classes of hair are very generally used. This is not so in the woollen and worsted trades.

Anthrax is common among animals all over Europe and Asia, and in most countries there is an increased incidence during the hot summer months. It is probable that in certain districts special conditions exist which make them permanent centres of anthrax infection. Here too hides and hair from contact with the soil may possibly become infected without the animals actually contracting anthrax.

In several former experiments by Bulloch and Craw (1906), Bulloch, Craw and Atkin (1908), and Craw (1908), we determined the relative efficiency of various filters in keeping back micro-organisms. The filters tested were the Doulton (“white” and “brown”), the Chamberland (“F” and “B”), the Berkefeld, and the Slack and Brownlow. Our methods of experimentation embraced filtration of cultures of microbes in bouillon, and the filtration of tap water under constant and variable pressures. The net result was that all the Slack and Brownlow, and nine out of ten of the Berkefeld filters employed gave contaminated filtrates within 15 minutes of the time the filtration experiment was commenced. Seven out of the ten Doulton “white” filters gave sterile filtrates for at least three days.

During the year 1904, a year which included four months of hot summer weather, the mortality among infants under one year old in England and Wales was 145.3 per 1000 births. Of this mortality 21.8% died of diarrhoeal diseases and 31.5% from wasting diseases.

In previous papers Professor Symmers and myself have called attention to the presence of agglutinins for the typhoid bacillus, the colon bacillus, and a bacillus of the alcaligenes class in the blood serum of patients suffering from cerebro-spinal fever from whose lumbar puncture fluid and in some cases from whose blood the Micrococcus intracellularis meningitidis (Weichselbaum) had been cultivated.