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As most of you know, one of the duties of the President of the American Society of Tropical Medicine and Hygiene specified by the by-laws is the presentation of an address at the annual meeting. I do not know what type of address those responsible for this provision had in mind, but a review of previous presidential addresses reveals a wide variety both of philosophical and scientific topics. Since I do not feel competent to address you on a philosophical subject, I have chosen to review a scientific topic which has been of interest to me during the past few years. In making this choice, I know that the subject matter will be of relatively little interest to those of you in other fields and for this I apologize. I shall illustrate later, however, that the topic I have chosen is especially appropriate for the site of our gathering this year and for the bicentennial which our joint meeting commemorates.
Léon Rosen (Sun,) studied this question.