Resume and Discussion of Experimental Findings
The principal positive result of the work has been the experimental reproduction of the lesion produced by the black-fly in characteristic histological detail by the use of preserved flies. The experimental lesions not only reproduced the pathological pictures, but followed a clinical course, which in local symptomatology especially, tallied closely with that of the bite. This the writer interprets as satisfactory evidence that the lesion is not produced by any living infective agent. The experiments performed do not identify the nature of the toxic agent. Tentatively they seem to bring out, however, the following characteristics.
1. The product of alcoholic extraction of flies do not contain the toxic agent.
2. The toxic agent is not inactivated by alcohol.
3. The toxic agent is not destroyed by drying fixed flies.
4. The toxic agent is not affected by glycerin, but is, if anything, more active in pastes made from the ground fly and glycerin, than in the ground flies as such.
5. The toxic agent is rendered inactive or destroyed by hydrochloric acid in a concentration of 0.25%.
6. The toxic agent is most abundant in the region of the anatomical structures connected with the biting and salivary apparatus (head and thorax).
7. The toxic agent is not affected by a 0.5% solution of sodium bicarbonate.
8. The toxic agent is not affected by exposure to dry heat at 100° C. for two hours.