Two generations of spore research: from father to son.

Harlyn O. Halvorson has played an active and defining role in the field of microbiology for more than 40 years. In this article, he reminisces on the major influence that his father, H. Orin Halvorson, had in the direction of his professional life. The two H.O. Halvorson's, often confused in the literature, became one of the only two father and son pairs to head the American Society for Microbiology in 1954 and 1977, respectively. Major scientists of the era, their research and their collaborations, are remembered in relation to their main works. Harlyn O. Halvorson's interest in bacterial and yeast spores, and especially spore germination in bacilli, is the highlight of this memoir. His scientific research thrusts, leadership at Marine Biological laboratories, Woods Hole, NACSEX (North American-Cuban Scientific Exchange) and elsewhere, his dedication to advanced students and numerous other endeavors, both scientific and political, are told here.