OF EXPERIMENTAL WORK 169 



Fertilization. — Eggs can be fertilized while in KCN (Blumenthal, 1927, 1928; Just, 

 1928 a; A. Scott, 1950). Effect on fertilization membrane (Just, 1928 a). 



Development. — Of fertilized eggs continues slightly in KCN (Heilbrunn, 1920 a; 

 Blumenthal, 1928, 1930; Just, 1928 a). 



Cleavage. — a. Arrest. Effective concentration to arrest cleavage in Arbacia punctulata 

 according to different observers: 

 M/ 1 0,000 KCN (Lyon, 1902). 

 Few drops of i/io % NaCN to 50 cc sea water (Loeb and Wasteneys, 1911a, 



Loeb, 1913 a, p. 26. 

 M/8,000 KCN (R. S. Lillie, 1914b). 

 0.000,625% KCN (Heilbrunn, 1920 a). 



N/i,ooo KCN, least concentration used (Blumenthal, 1928). 

 5 X 10-5 M KCN (M. M. Brooks, 1933). 

 1.6 X 10-* M KCN (Clowes and Krahl, 1940). 

 1.5 X 10-5 M HCN (Robbie, 1946b). 



5 X 10-2 M NaCN; very slow in lo"* M NaCN (A. Scott, 1950). 

 io~* to lO"* M cyanide agreed upon by all methods; the required concentra- 

 tion depends on the pH (Krahl, 1950). 

 b. Acceleration in very weak concentrations of KCN, M/ 1,000,000; delay if stronger 



than 4 M/ 1, 000, 000 (Lyon, 1902). 

 Cytology. — Of KCN treated eggs (Blumenthal, 1930, with photographs; A.Scott, 



1950)- 



Rhythms. — In mitotic cycle of sensitivity to cyanide (Lyon, 1902; Mathews, 1906a; 

 Heilbrunn, 1920 a; Just, 1928 a; Clowes and Krahl, 1934 b, 1935; Krahl, 1950; 

 Runnstrom, 1935 a). No phase sensitivity (Blumenthal, 1930; A. Scott, 1950). 



Later Stages. — Of development to plutei as affected by cyanide (Lyon, 1902 ; Child, 

 1916a, b, 1 94 1, p. 199, axial gradients and differential inhibition). 



Cilia of Blastulae and Plutei. — Paralyzed by KCN, recovery in sea water (Lyon, 

 1902). 



Recovery. — Delay in cleavage after return to sea water depends on concentration 

 of KCN and is independent of length of exposure (Blumenthal, 1928, 1930; Brinley, 

 1930). Cleavage inhibition caused by KCN is reversed by addition of ATP (Barnett, 



•953)- 



Prolongation oJLije of Unfertilized Eggs. — With N/ 1 000 KCN from one day (at 20 °C) 

 to 7 days (Loeb and Lewis, 1902; Loeb, 1913a, Chapt. X, 1915a; etc.) But Gorham 

 and Tower (1902) think this is due to killing of bacteria among the eggs by KCN; 

 this was answered by Loeb (191 1). The same question is discussed by Tyler, Ricci, 

 and Horowitz (1938) for ethyl alcohol. 



Salts and Cyanides. — Sodium cyanide prevents toxic action of salts etc. (Loeb, 

 1 9 10). M/iooo KCN decreases toxicity of Na salt, increases toxicity of K salt (R. S. 

 Lillie, 1912). 



Temperature and KCN. — More effective at higher temperatures Korr, 1937). 



Oxygen Tension and KCN. — Greater inhibition at low tensions (Robbie, 1946 b). 



Injection. — M/ioo KCN into fertilized eggs does not delay cleavage, but immersion 

 in this does delay it (Brinley, 1930). 



Methyl Cyanide. — Acts differently from KCN (Blumenthal 1928, 1930). 



Measurements. — Of cyanides (Robbie, 1946a). 



Respiration. — Reduced, with cleavage arrest. See Respiration A IV 4. First shown 

 by Warburg (1910) for P. lividus with N/ 10,000 NaCN which arrested cleavage and 

 reduced respiration to 20 % of normal. First shown for Arbacia punctulata by Loeb and 

 Wasteneys (1911a) with a few drops of 1/10% NaCN to 50 cc. sea water which 

 reduced respiration to J or ^ normal. Later data of Korr (1937) : 2.5 X io~' M KCN 



