222 ALPHABETICAL COMPILATION 



Viscosity. — NaCl increases viscosity in the order: KCI > NaCl > sea water > 

 MgClj > CaClj (E. B. Harvey, 1945). Heilbrunn gives the same order except that 

 KCI and NaCl are reversed (Heilbrunn, 1923, 1928, p. 146, 1943, p. 81). 



Breaking with Centrifugal Force. — Break more readily than in sea water in the order 

 of increasing viscosity (reverse order of stratification), that is, the most viscous (least 

 stratified) break most readily (E. B. Harvey, 1945). 



Parthenogenetic Agent. — NaCl added to sea water ; first used by Morgan (1898, 1899, 

 1900a, b, etc.); subsequently by Loeb, R. S. Lillie, and many others. NaOH has 

 also been used (Loeb, 1913 a, p. 148). 



The best parthenogenetic agent for Arbacia punctulata is: 30 gm. NaCl to one liter 

 of sea water for 20 minutes, then sea water. Or increase the salt content of sea water 

 by boiling to half its volume, leave eggs in this solution for 20 minutes, then sea 

 water (E. B. Harvey, 1936). Results vary with different batches of eggs, and one can 

 vary the solution and time slightly. 



Other Species and General References 



Bialaszewicz, 1927, 1929. A. lixula, P. lividus; electrolytes in eggs. 



Harvey, E. B., 1938 a. Parthenogenetic agent in Naples sea urchins. 



Heilbrunn, 1952. General Physiology, p. 519. 



Herbst, 1904. Sahs necessary for development. 



Loeb, 1913 a. Artificial Parthenogenesis. S. purpuratus, S. franciscanus, especially. 



Malm and Wachtmeister, 1950. Ps. miliaris, S. drobachiensis, amount Na in unfertilized and 



fertilized eggs. 

 Morgan, 1896. Sphaerechiniis granularis, astrospheres. 

 Robertson, 1939; Robertson and Webb, 1939; Webb, 1939. Inorganic composition of sea 



water and body fluids. 

 Rothschild and Barnes, 1953. P. lividus, inorganic constituents of egg; table of salts and 



species. 



SPECIFIC GRAVITY 



See Density 



SURFACE FORCES 



See Tension at the Surface 



SURFACE TENSION 



See Tension at the Surface 



TENSION AT THE SURFACE 



Surface Tension, Surface Forces 



Unfertilized Egg. — 0.2 dyne /cm., by centrifuge method (E. N. Harvey, 1931 c, 1932 a, 

 t>) 1937; 1938). 0.08 dyne/cm., by compression method; internal pressure 40 dynes/ 

 cm. 2 (Cole; 1932). Agreement with Harvey and Cole, by stretching (Norris, 1939). 



Fertilized Egg. — (Without fertilization membrane). Same as unfertilized till just 

 before cleavage, then increase. 0.03-0.05 dyne/cm. (for eggs late in season) (Cole 

 and Michaelis, 1932). 



Cleaving Egg. — 0.09 dyne/cm.; 62 dynes/cm.^ excess internal pressure when one 

 of two blastomeres is punctured (Sichel and Burton, 1936). 



Fertilization Membrane. — Formation due to lowered surface tension (Heilbrunn, 

 I9i3> igjSa, 1924a, 1925^)- 



Cytolysis. — Due to lowering of surface tension of plasma membrane (Heilbrunn, 

 1915a). 



