. The American Arbacia and other sea urchins. Sea urchins; Arbacia punctulata; Sea urchins -- Embryos; Biology -- Research. OF EXPERIMENTAL WORK I77 The classification is based on Sumner and Somer's book on Enzymes (1953) Proteolytic Proteolytic enzyme in granules of unfertilized egg (A. A. Woodward, Jr., 1949). Peptidase in matrix not in granules (Holter, 1936, 1949). Trypsin and chymotrypsin. In Psammechinus miliaris and Echinocardium cordatum, dissolve the vitelline membrane of the unfertilized egg, so that when fertilized, no fertilization membrane is formed, but the egg develops (Monne an
. The American Arbacia and other sea urchins. Sea urchins; Arbacia punctulata; Sea urchins -- Embryos; Biology -- Research. OF EXPERIMENTAL WORK I77 The classification is based on Sumner and Somer's book on Enzymes (1953) Proteolytic Proteolytic enzyme in granules of unfertilized egg (A. A. Woodward, Jr., 1949). Peptidase in matrix not in granules (Holter, 1936, 1949). Trypsin and chymotrypsin. In Psammechinus miliaris and Echinocardium cordatum, dissolve the vitelline membrane of the unfertilized egg, so that when fertilized, no fertilization membrane is formed, but the egg develops (Monne and Broman, 1944; Runnstrom, 1948a). Trypsin was used for A. punctulata by Runnstrom in 1950 and by Dan and Mazia in 1951 as the best method of obtaining fertilized eggs without fertilization membranes. Dan used 4 mg. crystalline trypsin in 100 cc. sea water for 10 minutes. Effect on membrane was first observed by Kunitz in 1932 (See A. R. Moore, 1949 a, footnote p. 243; 1949 b, footnote p. 207). Papain dissolves hyaline layer of developing eggs; no effect of ficin or trypsin (Northrop, 1947; E. B. H.). See under Hyaline Layer. "Hatching enzyme", a protease (Sugawara, 1943 a) dissolves fertilization mem- brane of normal blastulae, \n S. pulcherrimus (Ishida, 1936; Sugawara, 1943 a, b). In A. punctulata (Kopac, 1941). For earlier work on other forms, especially Ascidians, see Berrill (1929). Autolysis. See Lyon and Shackell (1910a). In sperm and egg extracts. Negative results (Gies, 1901). See Loeb (190I; 1913 a, chapter 19; older references given here). Also see Rothschild, 1952. Nucleases Polynucleotidase; localized in nucleus of egg, also in sperm; present in white half-egg, not in red half (Mazia, 1941). Withdrawn by Mazia in 1950. Ribonuclease, RNase. Drop in activity after fertilization which is maintained 20 hours (Bernstein, 1949; Krahl, 1950). Desoxyribonuclease, DNase. In eggs, half-eggs and sperm; not restricted to nuc- leus but distributed in cytoplasm in unf
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