1. See for example: Fardon et al., NATURE, 139, 589 (1937); Studies Institutum Divi Thomce, 2, 39 (1938) and 2, 233 (1939); Loof-Bourow et al., NATURE, 142, 573 (1938); 143, 725 and 144, 553 (1939); Studies Inst. Divi ThomÅ", 2, 137 (1938); 2, 155 (1939): Arch, exptl. Zellforsch., 22, 607 (1939); Biochem. J., 34, 432 (1940) and 35, 603 (1941); Cook et al., Atti X° congr. intern, chim., 5, 26 (1939); Biochem. J., 34, 1580 (1940).
2. We are greatly indebted to Dr. Florence Meier Chase of the Smithsonian Institution, Washington, D.C., for the algal cultures.