Joshua Lederberg

This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it.This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. To ensure a quality reading experience, this work has been proofread and republished using a format that seamlessly blends the original graphical elements with text in an easy-to-read typeface.We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.

This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it.This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. To ensure a quality reading experience, this work has been proofread and republished using a format that seamlessly blends the original graphical elements with text in an easy-to-read typeface.We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.

"Cancer viruses" have played a paradoxical role in the history of cancer research. Discovered in 1911 by Peyton Rous (1) at the Rockefeller Institute, they were largely ignored for several decades. Witness his eventual recognition for a Nobel Prize, but not until 1966-setting an all time record for latency, and testimony to one more advantage of longevity. In the 1950s, another Rockefeller Nobelist, Wendell Stanley, spearheaded a campaign to focus attention on viruses as etiological agents in cancer, his plat­ form having been the chemical characterization of the tobacco mosaic virus as a pure protein-correction, ribonucleoprotein-in 1935 (2). This doctrine was a centerpiece of the U.S. National Cancer Crusade of 1971: if human cancers were caused by viruses, the central task was to isolate them and prepare vaccines for immunization. At that point, many observers felt that perhaps too much attention was being devoted to cancer viruses. It was problematic whether viruses played an etiological role in more than a handful of human cancers.