1. The organism of Trench Fever is present in the “whole blood.”

2. The evidence seems to be in favour of the organism being an extra-corpuscular rather than an intra-corpuscular parasite.

3. The smallest quantity of whole blood which has given rise to the disease was 0.5 c.c.

4. The blood is infective from the first day of the disease, and in one case was found to be still infective after 443 days.

5. The microscopical examination of the blood has not up to the present revealed the organism or at least has not differentiated it from other granules present in blood.

6. There is some evidence that the organism may leave the body in the sputum and urine, but the chief and only way which has any practical significance is by means of a blood-sucking insect, the louse.

7. There is no evidence that infection takes place through food, drink or air, but only by inoculation of the organism by means of this insect.

8. The chief method of infection is not, as might be expected, by the bite of the louse, but by the infected excreta of the louse being brought in contact with an abraded surface of the skin.

9. After a louse has fed on a case of Trench Fever, five to nine days elapse before the excreta become infective.

10. If lice are fed on a case for some time a high percentage of the lice become infective.

11. There is no transmission of the organism of Trench Fever from infected lice through the egg to their offspring.

12. The tenth of a milligram of excreta has been found sufficient to set up the disease.

13. The organism of Trench Fever retains its virulence in louse excreta for at least four months.

14. The virulence of lice excreta is lost by exposure to dry heat of 100°C. for 20 minutes; to moist heat of 60°C. for a similar time.

15. It is doubtful if any of the laboratory animals are susceptible to Trench Fever.

16. It would appear that most men are susceptible to the disease, only a very few individuals having been found apparently naturally immune.

17. One attack seems to produce only a partial and limited immunity.

18. In regard to the etiology of Trench Fever there is strong evidence that the Rickettsia-like bodies found in infected louse excreta are the micro organisms of the disease, but as they have never been cultivated outside the body the final proof is still wanting.

19. The organism cannot be said to be a filter-passer; the evidence would seem to be more in favour of its being a small body such as the so-called Rickettsia.