The following contains a preliminary account of the work on the Etiology and Pathology of Trench Fever which has been done at the Lister Institute in connection with the War Office Committee on Trench Fever under the Chairmanship of Major-General Sir David Bruce, F.R.S. A first account from the Clinical side has been published in a paper by Major Byam, R.A.M.C., and his colleagues at the New End Military Hospital, Hampstead, and read before the Society for Tropical Medicine and Hygiene in May of last year. We have been mainly dependent for our material on Major Byam and the rest of the Medical Staff of the New End Hospital and are very much indebted to them for their help and courtesy. We are under an especial obligation to Lieut. Ll. Lloyd, R.A.M.C., who has carried out that part of the entomological work done at the Hospital, taking immense pains in supervision and in obtaining the material which we required.

The etiology of tetanus and gas gangrene presents a biological problem of an unusual nature. When the organisms which cause these diseases are deprived of toxin, by washing in tap-water saline or by washing and then heating, they are non-pathogenic to laboratory animals. In a recent investigation of the problem we have shown that soluble ionisable calcium salts enable detoxicated B. tetani, B. Welchii, B. oedematiens and vibrion septique to exert their pathogenic powers. We concluded that calcium owes this property to its local action on the tissues.

The action of univalent and bivalent salts on bacteria in affeting the conductivity of thick emulsions of the meningococcus and B. coli demonstrates the important fact, that they alter the conductivity of these germs in the living condition, in a very definite manner. In this alteration, the predominant part is played by the cat-ion.

All monovalent cat-ions, with the exception of the H-ion, such as those of Na, K, Li, Rb, produce a rapid increase in conductivity or a fall in resistance. In its early stages this increase in conductivity is readily reversible in these solutions. If allowed to follow its due course, however, it leads finally to death in about two hours, when the bacterial cells no longer offer any resistance to the passage of the ions. The conductivity of the emulsion then becomes that of the fluid in which the emulsion has been suspended.

Bivalent cat-ions and the H-ion, on the other hand, at first produce a slight fall in conductivity or an increase in resistance, followed, swecondly, by an irreversible increase in conductivity which is slow and gradual resulting finally in death after 48 or more hours. This is shown by the car-ions of Ca, Sr, Ba, and Cd.

In a balanced solution such as sea-water, blood plasma, Ringer's solution, van't Hoff's solution, where a certain quantity of CaCl2 antagonises a larger amount of NaCl and KCl, the conductivity of bacterial emulsions undergoes no change, but remains constant.

Dead in distinction to living bacteria offer little resistance to the passage of ions of a solution. It would seem the relativity high resistance of the bacterial cell is due to some condition present in the living and absent in the dead state.

It has been shown by experiments on animals that the condition of increased conductivity of the cell is coupled with a loss of virulence in the case of some pathogenic bacteria. It is not clear from these experiments if this is due to the actual death of the germs in a monovalent salt solution, or to a detoxicating action of these solutions on the germs. It would seem there is some evidence for believing that the latter takes place, as the lost lethal power returns in the presence of a small trace of Ca. In bivalent salt solutions no loss of toxicity takes place. It has been pointed out that the action of monovalent and bivalent salts on bacteria offers a new explanation of certain experiments with gas gangrene organisms, where it is at present considered that the action of the salts are on the tissues of the animal and not on the bacteria.

Owing to some regrettable slips in the arithmetical work of the paper dealing with eye colour and intelligence recently published in this Journal several of the constants are inaccurate. The whole of the calculations have now been re-worked and the correct values are given below. I have incorporated some fresh material, the analysis of which somewhat strengthens the conclusions already published.

The Harbour of Poole lies a few miles to the West of Bournemouth. It has an area approximately of 10,000 acres, but there is only a very narrow passage between its waters and the open sea. The width of this bottle-neck entrance is about 250 yards. The last published Admiralty chart gives the rate of the incoming tide through this narrow entrance at 3¼ knots, and of the outgoing tide at 4 knots. The local opinion is that these official rates err on the moderate side. The rapid ebb and flow of the tides has an influence in the bacteriology of the oysters within the harbour.