1. Aoyama, Y.: Jap. J. exp. Med.29, 535?545 (1959).
2. Bell, A. G., andD. G. Baker: Exp. Cell Res.38, 144?152 (1965).
3. Defendi, V., J. Lehman, andP. Kraemer: Virology19, 592?598 (1963).
4. Diamandopoulos, G. Th., andJ. F. Enders: Unpublished data.
5. Enders, J. F.: The Harvey Lectures, Series 59, p. 115?153, Academic Press, Inc., New York (1965).