Some unknown episodes in the history of population dynamics concerning the logistic law: the lesson of the great epidemiologists.

The author discusses the work of "the two great epidemiologists R. Ross and A. G. McKendrick. This talk is basically devoted to their 'lesson' about logistic theory and it is organised as follows: section 2 is devoted to McKendrick's [1911] contribution to the growth of microorganism populations, a paper which was not widely acclaimed, but which marks the first experimental laboratory verification of the logistic law. Section 3 is also devoted to McKendrick and to the way he repeatedly derived the logistic equation as a model for 'simple epidemics'. Finally, in section 4, we present Ross's 'A priori pathometry' theory that really emphasizes...the role played by the logistic law as the 'first principle' of the mathematical epidemiology."