1. B. dysenteriae of Flexner has been found in the stools of 17 out 19 cases of asylum dysentery; no evidence of the presence of the Shiga type was obtained.

2. In 18 cases examined one week to 14 months after an attack of dysentery, B. dysenteriae was found only once (3 weeks).

3. No evidence has been obtained of the presence of B. dysenteriae the faeces of ward contacts (26 cases) with either normal or diarrhoeic stools.

4. The fermentative reactions of B. dysenteriae of Flexner towards maltose and cane-sugar are variable.

By means of a method introduced by one of us (Wilson, 1907), a bacillus closely resembling B. faecalis alkaligenes was recently isolated from Belfast tap water. This bacillus, for the purposes of this paper, will be spoken of as B. Grosvenor, it having been attained from a house in Grosvenor Road. We find that emulsions of this bacillus are agglutinated, often in high dilutions, by the blood serum from practically every case of the cerebro-spinal meningitis at present existing in epidemic form in Belfast.

Bile salt media have been in use since 1900, and during the seven years which have elapsed it has been shown that B. typhosus, B. enteritidis (Gaertner), B. coli communis and similar organisms grow on these media just as well as on any other nutrient media. At 37°C. the growth of most of the organisms of the air and soil is inhibited by bile salt media.

These media can therefore be used with confidence for the isolation of B. typhosus and other intestinal organisms.

(1) Morphologically and culturally the Bacillus pseudotuberculosis rodentium (Pfeiffer) bears a strong resemblance to B. pestis.

(2) The filtrate from an autolysed agar culture of B. pseudotuberculosis rodentium (Pfeiffer) and a similar filtrate from a B. pestis culture both gave a precipitin reaction with pest serum.

(3) It has been found possible to immunise both guinea-pigs and rats against plague by means of inoculations of cultures of B. pseudotuberculosis rodentium (Pfeiffer), and this immunity lasted in many cases at least six months.

1. The time in which an animal or man exposed to compressed air becomes saturated with nitrogen varies in different parts of the body from a few minutes to several hours. The progress of saturation follows in general the line of a logarithmic curve and is approximately complete in about five hours in man and in a goat in about three hours.

2. The curve of desaturation after decompression is the same as that of saturation, provided no bubbles have formed.

3. Those parts of the body which saturate and desaturate slowly are of great importance in reference to the production of symptoms after decompression.

4. No symptoms are produced by rapid decompression from an excess pressure of 15 pounds, or a little more, to atmospheric pressure, i.e. from two atmospheres absolute to one. In the same way it is safe to quickly reduce the absolute pressure to one-half in any part of the pressure scale up to at least about seven atmospheres: e.g. from six atmospheres (75 pounds in excess) to three (30 pounds), or from four atmospheres to two.

5. Decompression is not safe if the pressure of nitrogen inside the body becomes much more than twice that of the atmospheric nitrogen.

6. In decompressing men or animals from high pressures the first part should consist in rapidly halving the absolute pressure: subsequently the rate of decompression must become slower and slower, so that the nitrogen pressure in no part of the body ever become more than about twice that of the air. A safe rate of decompression can be calculated with considerable accuracy.

7. Uniform decompression has to be extremely slow to attain the same results. It fails because it increases the duration of exposure to high pressure (a great disadvantage in diving work), and makes no use of the possibility of using a considerable difference in the partial pressure of nitrogen within and without the body to hasten the desaturation of the tissues. It is needlessly slow at the beginning and usually dangerously quick near the end.

8. Decompression of men fully saturated at very high pressures must in any case be of very long duration: and to avoid these long decompressions the time of exposure to such pressures must be strictly limited. Tables are given indicating the appropriate mode and duration of decompression after various periods of exposure at pressures up to 90 pounds in excess of atmospheric pressure.

9. Numerous experiments on goats and men are detailed in proof of these principles.

10. The susceptibility of different animals to compressed-air illness increases in general with their size owing to the corresponding diminution in their rates of circulation.

11. The average respiratory exchange of goats is about two-thirds more than that of man; they produce about 0·8 gram. of CO2 per hour per kilogramme of body weight.

12. The mass of the blood in goats is six and a half or seven and a half per cent. of the “clean” body weight.

13. The individual variation among goats in their susceptibility to caisson disease is very large. There is no evidence that this depends directly on sex, size or blood-volume: there is some evidence that fatness and activity of respiratory exchange are important factors.

14. Death is nearly always due to pulmonary air-embolism, and paralysis to blockage of vessels in the spinal cord by air. The cause of “bends” remains undetermined; there are reasons for supposing that in at least many cases they are due to bubbles in the synovial fluid of the joints.

15. In our experiments bubbles were found post-mortem most freely in the blood, fat and synovial fluid; they were not uncommon in the substance of the spinal cord, but otherwise were very rarely found in the solid tissues.