OF EXPERIMENTAL WORK l6l 



Lindahl, ig^2 c.Psammeckinus mkrotuberculatus, fine colored picture, p. 330; probably Ps. 



miliaris is the same. 

 Linderstrom-Lang, 1938-1939. Ps. miliaris, diagram. 

 Monne, 1944 b. Echinocardium caudatum, Ps. miliaris. 



See under Centrifuged Eggs, Part III, Chapter lyd, p. 127. 



CLEAVAGE, ACCELERATION 



Many of the substances listed under Cleavage are treated more fully 

 under Respiration 



Acetyl Choline. — Acceleration in low concentrations, inhibition in high (Balzer and 

 Villee, 1951; Villee and Villee, 1952. 



Alcohols. — Slight acceleration (Blumenthal, 1928); in low concentrations (Water- 

 man, 1936). 



Alkali. — Slightly alkaline sea water accelerates cleavage i^ or 2 cc. of i /lo-normal 

 NaOH to loo cc. sea water (Loeb, 1898, but see 1913 a, p. 35). Also see Glaser 

 (1914b) and Medes (1917). Acceleration at pH 8.2 to 9.2, maximum at 8.8. Delayat 

 pH 9.4 (Smith and Clowes, 1924c). For Echinus esculentus see B. Moore, Roaf and 

 Whitley (1905). 



Calcium-free Sea Water. — Accelerates cleavage; excess Ca delays cleavage (Shapiro, 

 1 941; Scott and Pollen, 1951). 



Carcinogenic Hydrocarbons. — (Choleic acid compounds). Acceleration of cleavage 

 (Keltch, Krahl, and Clowes, 1937). Retarded and atypical cleavage (Lucke, Parpart, 

 and Ricca, 1941). 



Copper Chloride. — Acceleration in very dilute CuClj, lO"^^ M (Finkel, Allee, and 

 Garner, 1942; Allee, Finkel, et al., 1942). See under Delay. 



Crowding. — Early cleavages accelerated if eggs moderately dense, delayed if very 

 dense (Allee and Evans, 1937 a, b, c). For S. drdbachiensis see Frank and Kurepina 

 (1930); for P. lividus see Maxia (1933); for Anthocidaris crassispina, Pseudocentrotus 

 depressus, S. pulcherrimus see Sugiyama (i938e). 



Cyanide, Potassium. — Accelerates cleavage in very weak concentrations, io~® M; 

 arrests cleavage in stronger concentrations, io~* M to lo"* M (Lyon, 1902). See 

 under Delay and Cyanides. 



Cystin. — Acceleration of cleavage and development (Mathews, 1909); not con- 

 firmed by King (191 2). 



Egg Extracts. — "Homotypic extracts.'" Some accelerate cleavage, some do not (Allee, 

 Finkel, et al., 1942). Acceleration if fats removed (Peebles, 1929). 



Heat. — Cleavage accelerated as temperature is raised up to about 31° C. (Loeb 

 and Wasteneys, 1911a; Loeb, 1913a, p. 32; Loeb and Chamberlain, 191 5; Hoadley 

 and Brill, 1937). See Tables 3 and 4. Highest temperature permitting cleavage is 

 about 28 °C. ; killed at 32° C. (E. B. H.). For Ps. microtuberculatus and Sphaerechinus 

 granularis see Peter (1905). For P. lividus see Ephrussi (1933); for S. purpuratus, 

 Lytechinus anamesus and Dendraster excentricus see Tyler (1936 a, b). See under Delay. 

 Hydrogen Ion Concentration. — See below under pH. 



Hypotonic Sea Water. — 94-98 %. Accelerates first cleavage 5 % of normal time 

 (Cornman, 1943). 



Mechanical Shocks and Vibrations. — Accelerate cleavage (Meltzer, 1903; Mathews 

 and Whitcher, 1903). Whitney (1906) thinks this is due to rise in temperature. 

 Shaking accelerated cleavage in A. lixula also (Lyon 1903). 



Methylene Blue. — Cleavage accelerated with 5 x lO"* %, retarded with 5 X lO"* % 

 (M. M. Brooks, 1933, 1943). Shapiro (1948a) finds delay; also Clowes and Krahl 

 (1936a). See Krahl (1950, Tables VIII and IX). See under Delay. 



Oxygen Lack, Partial. — May accelerate cleavage (Loeb, 1895a, 1905 translation). 



