OF EXPERIMENTAL WORK l8l 



enzyme" (Kopac, 1941a); see Part II; Chapter 14a, blaspula. (7) Isosmotic KCl 

 while membrane is elevating, 1.5 minutes after insemination (Kopac, 1940a; 

 Chambers, 1942, 1944). (8) i.o M urea while membrane is elevating (Chambers, 

 1940, 1942; Kopac, 1940 a, 1943; Moser, 1940; A. R. Moore, 1930 a for Strongylo- 

 centrotus purpuratus) . (9) 4 mg. crystalline trypsin in 100 cc. sea water for 10 minutes, 

 or O.I % noncrystalline trypsin of Merck, as membrane is elevating (Dan, 1951 

 unpub. ; see Runnstrom and co-workers for other species, especially Runnstrom, 

 1948 a). See under Vitelline Membrane. 



A method for removing fertilization membranes from large quantities of eggs by 

 bolting silk has been described by Lindahl and Lundin (1948) for Paracentrotus lividus. 



Effect of Ageing or Repeated washings. — Membrane retarded or prevented (E. N. 

 Harvey, 19 14, after 52 hours; Goldforb, 1918a, b, after 42 hours; F. R. Lillie, 19 14, 

 after 11 to 33 washings) . 



Effect of Calcium-free Sea Water. — As medium. No membrane is formed and there 

 is no cleavage though sperm are active (Loeb, 1915a; E. B. H. unpub.). Also for 

 Ps. microtuberculatus (Monroy, 1949). 



Calcium. — In medium not necessary for hardening of membrane (Chambers, 



1942)- 



Effect of Heparin. — No membrane formed (C. V. Harding, 195 1). 



Effect of lodosobenzoic Acid. — And cytoplasmic fraction. Membrane thicker and 

 change of birefringence ; hatching inhibited, membranes do not dissolve (Monroy 

 and Runnstrom, 1952; Runnstrom and Kriszat, 1952 a, c). Effect of other SH- 

 reagents (Runnstrom and Kriszat, 1952 a). 



Effect of Electric Current. — On fertilized egg. Fertilization membrane nearer the 

 egg at anode (McClendon, 1910b, 1914a; Dan, 1933). 



Effect of Ultraviolet "Blitz'''. — On unfertilized egg. Fertilization membrane forms 

 on one side only (E. N. Harvey, 1942). See Spikes (1944) ior Lytechinus pictus. 



In centrifuged eggs and fractions . — Membrane thinner at centripetal pole of whole 

 egg and white halves ; very thin on clear quarters and breaks at oil cap if fertilized 

 immediately after centrifuging. Thicker and closely investing on red half, mitochon- 

 drial quarter and pigment quarter (E. B. Harvey, 1933 b, 1940 c, 1946). 



Other Species and General References 



Carter, 1924. Sphaerechinus granularis . 



Chase, 1935. Strongylocentrotus purpuratus, Dendraster excentricus . 



Endo, 1952. Japanese species. 



Gray, 1922. Ps. miliaris. 



Hobson, 1932 a. Ps. miliaris. 



Hyman, 1923. S. purpuratus, S.franciscanus. 



Just, 1 91 9. Echinarachnius parma. 



Just, 1939 b. The Biology of the Cell Surface. General. 



F. R. Lillie, 1919. Problems of Fertilization. General. 



F. R. Lillie and Just, 1924. Fertilization in Cowdry's General Cytology. 



Loeb, 1912 a. The Mechanistic Conception of Life. 



Loeb, 1913 a. Artificial Parthenogenesis and Fertilization. 



Loeb, 1 916. The Organism as a Whole. 



A. R. Moore, 1930a, b; 1949a, b; 1951a. S. purpuratus, Dendraster excentricus. 



Monroy, 1949. Psammechinus microtuberculatus. Other references may be found in review by 



Runnstrom 1949 a. 

 Motomura, 1934a, 1941b, 1950c. S. pulcherrimus, etc. 

 Runnstrom, 1949a, b, c; 1952a, b. General. Other references to Runnstrom, Monroy, and 



co-workers may be found especially in 1949 a. 



