OF EXPERIMENTAL WORK I55 



ARTIFICIAL PARTHENOGENESIS 



See Parthenogenesis 



Amount in egg. — 1.90 mg Ca per 10® eggs (10® eggs = 0.124 g"^- ^^'"y weight) or 0.047 

 millimols (Page, 1927b). 



Total Ca is about 0.3 mg. per cc. eggs; same in unfertiHzed and fertilized eggs. Ex- 

 changeable Ca per cell is 19.2 X lO""® mg. The concentration of free Ca in the unfer- 

 tilized egg is of the order of 0.0005 M and increases by o.ooi M on fertilization; 

 bound Ca decreases on fertilization by about 15%. Ca release on fertilization and 

 cytolysis (Mazia, 1933, 1937, 1940; Heilbrunn, Mazia, and Steinbach, 1934). 



Sea water. — At Woods Hole contains 0.428 gm. Ca per liter at 20° C. (Page, 

 1927c, 1928). 



Perivisceral Fluid. — Contains 0.395 mg./cc. of Ca as against 0.41 mg./cc. in sea 

 water (Schechter, 1937, from analysis by Mazia). 



CaCl^- — Isotonic with sea water at Woods Hole is 0.30 M (M. B. L. Chemical 

 room) usually given as 0.34 M. 



Radioactive Ca (Ca*^). — Accumulated only by eggs with jelly coats and for only 

 six hours after fertilization (Rudenberg, 1953). 



Surface Precipitation Reaction. — With breakdown of pigment granules; calcium 

 necessary (Heilbrunn, 1928, Chapt. 13; 1930, 1943, p. 86; 1952, p. 102; Costello, 

 1932; et al.). Effect of anaesthetics (Mg and ether) on surface precipitation reaction 

 (Heilbrunn, 1934). For other references to calcium and breakdown of pigment 

 granules see Gross (1951); and of other granules (yolk) see Costello (1932) and 

 (cortical) see Moser (1939 a, b). 



Vitelline membrane. — Made brittle by Ca (Heilbrunn, 1928, p. 149; Chambers, 

 1944, 1949, 1950; see Kopac, 1940 a). 



Surface potential of egg. — Effect of Ca (Dan, 1936). 



Hyaline la jier.— hack of calcium prevents formation of, or causes dissolution of, 

 hyaline layer of fertilized egg so that blastomeres fall apart. First described by Herbst in 

 1900 in Echinus microtuberculatus and subsequently by many others. Effect of lack of 

 Ca on hyaline layer in Arbacia punctulata and other species described by E. B. 

 Harvey (1933 b, 1934). See Hyaline Layer. (Plate XVI, Photograph 9). 



Jelly. — Dissolves in Ca-free sea water (E. B. H.). 



Ca Necessary for Fertilization. — No fertilization membrane is formed if fertilized in 

 Ca-free sea water though sperm are motile (Loeb, 1915a; Glaser, 191 5; E. B. H. 

 unpub. ; also Monroy, 1 949 for Psammechinus microtuberculatus) . But see Shapiro ( 1 941 ) . 



Cleavage. — Addition of calcium (3 times amount in artificial sea water) delays 

 cleavage, lack of calcium accelerates cleavage (Shapiro, 1941). Delay and arrest 

 with calcium (Schechter, 1937). Effect on furrowing (Scott and Pollen, 195 1). 



Effect on Cytolysis. — CaClj prevents cytolysis (R. S. Lillie, 1911a, b, 1912; Page, 

 1924; Schechter, 1936). When used for a long time, CaClg causes cytolysis (Heil- 

 brunn, 1928, p. 147). 



Antagonism. -^Cz. counteracts NaCl and other Na and K salts (Loeb, 1900a; 

 Mathews, 1905; R. S. Lillie, 191 1 a, b, 1912, 1914a; McCutcheon and Lucke, 1928; 

 Heilbrunn, 1943, p. 463). Ca antagonises Mg (Heilbrunn, 1934). 



Respiration. — For other species (Hultin and Vasseur, see list below). 



Permeability to water. — Decreased by isotonic CaClj (R. S. Lillie, 19 10; McCut- 

 cheon and Lucke, 1928; Luck6 and McCutcheon, 1929, 1932) ; no effect on fertilized 

 eggs (R. S. Lillie, 1918 b). Permeability to ethylene glycol not significantly changed 

 by Ca (Stewart and Jacobs, 1936). 



Viscosity. — Decreased by isotonic CaClg (Heilbrunn, 1923, 1928, p. 146, 232; 



