In a recent publication1 I described a gas analysis apparatus suitable for rapid and accurate laboratory work. This apparatus is, however, somewhat cumbrous, and cannot easily be conveyed from place to place, as is very often required in investigations relating to questions of hygiene. It also occupies a good deal of working space in a laboratory, as it cannot be moved from its place without a good deal of trouble. On the other hand the already existing forms of portable gas analysis apparatus for technical work are too inaccurate for many of the requirements of work in hygiene and physiology. I have therefore designed an apparatus with a view to meeting these defects as far as possible2.

In the samples of “blown” preserve tins examined by me, organisms of an intestinal type were present, which on reinoculation into sound tins gave rise to a gaseous decomposition.

No toxic symptoms were produced on feeding guinea-pigs with the contents of the “blown” tins.

Animals protected from fleas by means of a sufficiently broad layer of “tangle-foot” and placed in plague-infected houses do not contract plague, but the control animals, not so protected, on several occasions (24 per cent.) developed the disease. Out of 247 fleas caught on the “tangle-foot,” 60 p.c. were human, 34 p.c. were rat and 6 p.c. were cat fleas. Plague-like bacilli were demonstrated in the stomach contents of one out of 85 human fleas dissected, and of 23 out of 77 rat fleas.

In the present paper we describe the results of further investigations on the morphology and staining characters of Piroplasma canis, as well as a large number of observations on the living parasites. Our previous papers (1905) contained the results of studies preliminary to the investigation of the life-history of the parasite, but further work was unavoidably interrupted owing to the difficulties attending this form of research—we unaccountably failed to transmit the disease after several passages through dogs, and met with great difficulties in rearing progeny from infected ticks. Consequently the observations had to be discontinued until, after several failures, infected ticks (Haemaphysalis leachi) capable of transmitting the disease, had been received from South Africa through the kindness of Mr C. P. Lounsbury, Government Entomologist, Cape Colony. With this fresh strain of the disease we have succeeded in demonstrating various points in the morphology of the parasite which have hitherto escaped observation, and have worked out its method of multiplication in the living blood. Further studies have also been made on the vitality of the parasite outside the body in culture fluids, but these and other studies on the cycle of development within the tick are reserved for future communications.

1. Cultures of Gärtner's bacillus grown on broth do not excrete any large amount of toxin into the fluid medium.

2. Suspension in broth made from ordinary agar cultures and killed by means of heat (30 mins. at 60°C.) are fairly toxic.

3. The most toxic preparations were obtained by autolysis of the bacilli, especially in the presence of toluol.

4. Cultures grown on agar and killed by means of chloroform vapour lose their toxicity to a considerable extent.

5. Autolysis takes place best in the presence of distilled water or of normal saline.

6. Autolysed material sterilised by heat is more toxic than the filtrate obtained from the same digest.

7. Shaking the bottles during the process of autolysis increases the yield of toxic substances.

8. Gärtner toxin withstands heating to 100°C. for 30 mins.

9. Paratyphoid B. bacillus cultures on autolysis yield a filtrate quite as toxic as those from the Gärtner bacillus itself.

10. Paratyphoid toxin is also heat resistant (100° for 30 mins.).

11. A colon bacillus gave a toxin which was fatal to mice. It was not heat resistant.

12. Feeding experiments with Gärtner-infected meat, both cooked and uncooked, proved successful.

13. So far as the present experiments go the connection between virulence and toxicity does not appear to be very definite.

14. The Gärtner bacillus contains a toxin of the endotoxin type as is shown in comparing results 1 and 3. This toxin gives rise to very definite clinical symptoms of which the gluing together of the eyelids and the prolonged narcosis before death are the most notable. The post-mortem signs have much in common with those arising from other intestinal intoxications.

The undoubted fact that milk may act as a vehicle for the transmission of a number of diseases has directed considerable attention to the Bacteriological and Public Health aspects of milk. Yet it cannot be said, tuberculosis excepted, that the bacteriological examination of milk has afforded in the past much assistance in the prevention of disease, while only very occasionally has a subsequent examination served to elucidate the cause and origin of a milk-spread epidemic. A survey of the literature of the subject will show that although extensive work has been carried out upon the bacteriology of milk, the subject is so large and many-sided that what is known is but an insignificant proportion of what requires to be ascertained. A great deal of the work done has been in relation to tuberculosis. Almost all the milk examinations have been carried out with mixed milk samples, and not with quite fresh milk from individual cows.

It is usually accepted that in precipitin reactions a definite quantity of precipitin interacts with a definite quantity of homologous proteid, and further that in ordinary circumstances the interacting quantities combine to give rise to a precipitate, the precipitum. From this it follows that, if a known weight of serum containing precipitin be allowed to react with various weights of homologous proteid and if the quantities of proteid be sufficiently varied, certain reactions will be completed and others will be incomplete. The addition of precipitin and of homologous proteid to the superfluid of each reaction will determine the presence of excess of precipitin or of homologous proteid in such fluid. Conversely, if a known weight of the homologous proteid be allowed to interact with various weights of serum containing precipitin, it will be possible to determine in a similar manner those reactions which have been completed and those in which the homologous proteid or the precipitin is in excess. If the first stated proposition be correct, the results of these two series should coincide. A definite weight of serum containing precipitin should interact with a definite weight of proteid to from the precipitum.

Ceratophyllus fasciatus1 is the flea usually found on Mus decumanus in Great Britain, and this is also the case, apparently, throughout Northern and Central Europe. The common house mouse, Mus musculus, occasionally harbours this parasite also, though its usual flea is Ctenopsylla musculi.

Since it would hardly be possible to conceive a more complex medium for the conveyance of disease than cows' milk, the solution of the problems connected with the origin and source of epidemic diarrhoea is not materially advanced by the general recognition of the fact that in the majority of fatal cases, cows' milk is the vehicle of infection.

In the light of the controversy which is beginning to be waged in connection with Schaudinn's researches into the life-history of Halteridium noctuae, and especially in view of the papers by Prof. Ross which have been appearing in this Journal, the accompanying illustrations are likely to be of interest. They represent forms of parasite which I have found in the alimentary tract of the flea, Pulex cleopatrae Roths. and possibly other species, when searching for a cycle of development for Haemogregarina balfouri Laveran in that insect which, along with mites, infests the Sudan jerboa (Jaculus gordoni). The illustrations were prepared by Mr Richard Muir from drawings which I made in Khartoum.

The key to the anatomy of the mouthparts of the flea and to the understanding of the mechanism of blood sucking is the recognition of the pricking epipharynx and of the hypopharynx with its salivary pumping apparatus. In general it may be stated that the epipharynx makes a way through the skin for the mandibles, that the mandibles enlarge and lacerate the hole thus bored and convey into it the salivary secretion which is pumped, by means of the salivary pump, down the salivary canal contained in them, and that the aspiratory pharynx aspirates blood from the now congested wound along the blood channel formed by the approximation of the epipharynx and the two mandibles. The whole complex of parts is adapted to form two channels, an effluent along which saliva is pumped down and an affluent along which blood is pumped up.

Many investigations relating to Hygiene and Public Health, possessing permanent scientific value, appear in Annual Reports of Medical Officers of Health, Blue Books and other Publications of Official Bodies within the British Empire. These are not easily available and as a rule no record of them, appears in scientific journals or in an accessible form; consequently much valuable work is lost sight of. To obviate this difficulty the Editors of the “Journal of Hygiene” propose to publish from time to time abstracts of such publications, or parts of them, as appear of sufficient permanent interest. They will be glad to receive copies of official Reports coming under the above description.

1. A mixture of serum and its anti-serum has the property of fixing or deviating complement and thus interfering with haemolysis. In this there is a close analogy to the fixation of complements by cellreceptors in association with immune-bodies.

2. A large number of different complements may be fixed by the same combination of serum and anti-serum: some complements however may not be fixed.

3. The amount of homologous serum necessary to produce a distinct deviation of complement is extremely small—·000,01 c.c. and even less: as a rule it is many times less than the amount necessary to give a visible precipitate with the anti-serum.

4. When a precipitate forms, the deviating substance is present in the precipitate and may be so exclusively: precipitation is however not essential, as the deviation phenomenon may be given by an anti-serum without the formation of a precipitate.

5. The precipitin and deviation tests give results which are in great part in accord as regards specificity.

6. For any given amount of anti-serum there is an optimum amount of homologous serum which gives maximum deviation of complement: above as well as below the optimum the deviation diminishes.

7. The deviation phenomenon produces an effect similar to an “anti-complement” action and the views generally held with regard to anti-complements require revision. It is however still left an open question whether true anti-complements exist.

For some years past a careful record has been kept of the method of feeding, not only of all children dying of epidemic diarrhoea, but also of all babies under one year of age in the houses of the working classes, which are visited year by year in the course of routine house-to-house inspections by the sanitary inspectors in my department. It is impossible to ask the necessary questions at every house, but in most houses information has been given without difficulty, and it may be taken as certain that the 1259 babies living in 10,308 houses who are classified in the first four columns of Table I belong approximately to the same social stratum as the 121 babies dying from diarrhoea who are classified in the four last columins of the same table.

1. Twenty-six passages from rat to rat have been effected without recourse to artificial media. The time taken was 89 days.

2. Our results furnish no evidence that the virulence of the bacillus used for the passages undergoes any alteration.

3. The experiment gives evidence of the varying susceptibility to plague of the Bombay rat.

In the month of June, 1905, no fewer than 99,518 natives were employed on mines and works in the labour districts of the Witwatersrand, and the neighbouring mining areas of Klerksdorp, Heidelberg, and Vereeniging. In addition to these there were also working on the gold mines over 45,000 Chinese labourers. This vast industrial army is recruited from many and in great measure from very distant sources. Of the natives employed during the year ending June, 1905, the whole of British South Africa furnished only just over 32%: less than 2% came from British Central Africa: 60% were drawn from the Southern Portuguese East Coast provinces; and 3.6% from the Portuguese provinces north of latitude 22°. German South-West Africa contributed under 1%, but this area has latterly ceased to be a source of supply.

In 1898 I published1 a brief account of certain amœbulæ and flagellulæ found by me during the previous year in mosquitoes near and in Ootacamund, India. Similar parasites were frequently observed by me subsequently in various species of Culicina, especially in C. fatigans Wiedemann, and once in an Anophelina. Since then what appear to be the same, or at least closely allied, organisms have been described as occurring in Anophelina by Chatterjee, Stephens and Christophers, and L´ger, the last of whom named them Chrithidia fasciculata. Their habitat appears to be principally the intestinal cavity of the larva, pupa and imago. Many of them (as still well shown in an unstained preparation of my own made in Calcutta in 1899) have a considerable resemblance to trypanosomes—a resemblance which appears to be further suggested by the stained preparations of Léger, Christophers, and Stephens.

The experiments here recorded are not sufficiently numerous to justify any decided opinions as to the value of the tests with these various substances in differentiating certain bacilli which very closely resemble the diphtheria bacillus. They show, however, that most of the diphtheria-like organisms tested produce less acid than the diphtheria bacillus. Hofmann's bacillus and a diphtheria-like bacillus from the normal ear can be easily differentiated, since they from no acid. Any bacillus which acts on mannite or saccharose could also be easily differentiated.