1. Lycke, E.: Arch. ges. Virusforsch.8, 267 (1958).
2. A review is presented byS. Gard andO. Maaloe in The Viruses volume 1 p. 359?427, Acad. Press. Inc. London (1959).
3. Lund, E., andE. Lycke: Acta Microbiologica Scand. in press.
4. Reed, L., andH. Muench: Am. J. Hyg.27, 493 (1938).
5. Bonnier, G., andO. Tedin: Biologisk variationsanalys, first edition, Stockholm (1940).