The big, green silkworms crawling around the Harvard laboratory of Assistant Professor (of zoology) Carroll Milton Williams look like normal specimens, but when Professor Williams tests them with a Geiger counter, they make it rattle like a cornpopper. The caterpillars are radioactive. Soon they will spin cocoons of radioactive silk and will eventually emerge, if not disturbed, as radioactive moths.
Professor Williams and his associate, Paul Charles Zamecnik, Harvard associate in medicine, have a serious purpose. They are trying to study the structure of protein, the basic substance of living creatures. Fibroin, the principal constituent of silk, is a protein. Scientists know...