S. E. Luria's autobiography adds another gem to the Sloan Foundation series which includes Freeman Dyson's Disturbing the Universe and Hendrik Casimir's Haphazard Reality. The molecular biologist and Nobel laureate writes with a crispness and concision that mirrors his outlook and his work. He is proud of ""reductionist"" science; he is committed to a life of reason, to socialist ideals and political action. Early on, he confides also, he committed himself to acquiring a musical education and, later, to learning and appreciating ""modern"" poets. All this is told in chapters that compartmentalize the life: the developing years as a Jew in a modest Turin household in pre-fascist Italy; the scientific achievements; the teaching career; the marriage, emotional life, political activities. Luria set out to study medicine, but a fascination with physics led to Fermi in Rome, and then to a stint at the Pasteur Institute and the study of genes as molecules--a fanciful idea in the Thirties. World War II found him in New York and subsequently at Bloomington, Indiana. (He now heads MIT's Center for Cancer Research.) The slot machine and the broken test tube of the title were both scientific turning points. In the first instance, Luria made an intuitive leap while watching a slot machine at a college dance. He had been speculating about a problem dividing biologists: did the viruses that infected bacteria (""phages"") induce some bacteria to become resistant, or was resistance the result of a random bacterial mutation? If the latter, then an experiment could be set up that would show certain cultures of bacteria infected by phage to be ""jackpots"" with numerous resistant colonies, while others would be duds. So it was. The broken test tube was indeed an accident, but one that resolved yet another mystifying question: why did some bacteria infected by phage die, without phage progeny showing up in the culture dish? (The bacteria produced enzymes, it turned out, that attacked the phage DNA: the bacteria were still killed, but the phage would not reproduce in that bacteria or in related strains. When Luria's test tube broke, he borrowed a colleague's that contained bacteria of an unrelated strain; the enzyme-modified phage grew happily in this strain--thus demonstrating the new phenomena of ""restriction"" and ""modification."") Luria's chapters on molecular biology and its shapers are fine additions to the genre; the fascination of the book, however, is in the man. Gratuitous remarks on biography-writing apart, he presents himself with forthright honesty and integrity--unexpectedly disclosing, at the end, that he suffered years of depressive episodes prior to drug treatment. A remarkable life--short on humor, perhaps, but abundant in courage and conviction.