Many of the original research and survey monographs in pure and applied mathematics published by Birkhäuser in recent decades have been groundbreaking and have come to be regarded as foundational to the subject. Through the MBC Series, a select number of these modern classics, entirely uncorrected, are being re-released in paperback (and as eBooks) to ensure that these treasures remain accessible to new generations of students, scholars, and researchers.

The antimicrobial activity of ofloxacin was tested against 15 standard strains and 37 clinical and environmental strains of Legionella pneumophila by agar dilution susceptibility studies with a new growth medium. The ofloxacin MICs were inoculum dependent and ranged from 0.03 to 0.125 ,ug/ml. The antibacterial activities of other agents tested relative to ofloxacin were rifampin > ofioxacin > josamycin > pipemidic acid. Ofloxacin, at concentrations equal to or greater than 0.05 ,ug/ml, inhibited the growth of L. pneumophila grown in human monocytes. The therapeutic efficacy of ofloxacin in experimental guinea pig L. pneumophila pneumonia was greater than that observed with erythromycin or josamycin therapy; it was less effective than was rifampin. Ofloxacin was very active against intracellular L. pneumophila in these experiments and should be studied in the therapy of human Legionnaires disease.

A time reversion of a Markov process was discussed by Kolmogoroff for Markov chains in 1936 [6] and for a diffusion in 1937 [7]. He described it as a process having an adjoint transition probability. Although his treatment is purely analytical, in his case if the process Xt has an invariant distribution, the reversed process zt = x-t is the process with the adjoint transition probability.In this discussion, however, it is very restrictive that the initial distribution of the process must be an invariant measure.On the other hand, the adjoint (or dual) process of a Markov process can be defined with respect to any sub-invariant (or excessive) measure, and this was done by Nelson [15] and Hunt [3]. Ever since the notion of the adjoint processes has an important role in the theory of Markov processes (cf. e.g. also proved that for Markov processes obtained by killing, the reversed processes from the killing times have temporal homogeneity.The purpose of this paper is to prove that the reversed processes from appropriate random times {L times cf. § 2) preserve temporally homogeneous

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