Bibliographical noteFunding Information:
The authors are indebted to Dr. Lee Vernon of Microbiological Associates for electron microscopic examination of chicken embryo tissues, and Mrs. Cecile Willems and Miss Eileen Boszko for excellent technical assistance. These studies were supported in part by contract PH-70-206% and NIH-NCI-71-2174 of the Special Cancer Virus Program, National Cancer Institute, Bethesda, MD 20014, and by Grant NP-271 of the American Cancer Society. This is publication No. 1423 of the Cancer Commission of Harvard University.