OF EXPERIMENTAL WORK 2O9 



5 °C. (Just, 1939 b, p. 202). Excess sperm (F. R. Lillie, 1919, p. 260; J. M. Clark, 1936). 

 But Just (1928a) thinks not. At pH 7.4-6.8, none at 7.4-9.8 (Clowes and Smith, 

 1923, Smith and Clowes, i924d; J. M. Clark, 1936) ; A. Scott, 1946). Organic acids; 

 aspartic (King, 1912); butyric (Just, 1939b, p. 202). SH-reagent, p-chloromercuri- 

 benzoate (Runnstrom and Kriszat, 1952a). Substances used by Hertwigs (1887): 

 chloral hydrate 0.2 %; cocaine hydrochloride 0.025%; nicotine i drop to 200 cc; 

 morphine sulphate 0.6%; strychnine sulphate 0.1%; quinine sulphate 0.05%, 

 (J. M. Clark, 1936). Salts of Na, K, Ca, Mg (J. M. Clark, 1936). Fat solvents, alcohol, 

 ether, chloroform, ethyl urethane (J. M. Clark, 1936). Cleavage of polyspermic eggs 

 (Scott, 1946). 



Other Species (additional) 



Baltzer, 1908. Paracentrotus lividus, Psammechinus microtuberculatus. 



Brachet, 1922. P. lividus, during, maturation. 



Bury, 1 91 3. P. lividus, Ps. microtuberculatus, cold. 



Ishida and Nakano, : 950. Strongylocentrotus pukherrimus, fertilization after parthenogenesis. 



Rothschild, 19533. P. lividus, nicotine; 1954, Quart. Rev. Biol. 29: 332-342. 



Rothschild and Swann, 1950, 1951. Ps. miliaris, nicotine. 



Runnstrom and Monne, 1945 a. Ps. miliaris, Brissopsis lyrifera, during maturation. 



Sugiyama, 1947, 1951. S. pukherrimus etc., after refer tilization. 



Wilson and Mathews, 1895. Lytechinus variegatus. 



POTASSIUM 



Amount in Egg. — 2.445 mg. potassium per 10* eggs (10® eggs = o. 1 24 gm. dry weight) 

 or 0.063 millimoles (Page, 1927b). 



Amount in Sea Water. — At Woods Hole. 0.412 gm. per liter at 20 "C. (Page, 1927c). 



K : Na in Eggs. — As 1.90 : i ; in sea water K : Na as 0.0213 : i (Blanchard per 

 Howard, 1 93 1 ) . Twenty times as much K in eggs as in sea water ; about same amount 

 in unfertilized and fertilized eggs (Shapiro and Davson, 1941). 



KCl Isotonic. — With sea water at Woods Hole is 0.53 M (M.. 3. L. Chemical Room). 



Loss of K. — By eggs in sea water and accumulation of K in sea water with excess K, 

 (Shapiro and Davson, 1941). 



Uptake. — And loss of K^^ ^y unfertilized and fertilized eggs (E. L. Chambers, 

 White, Jeung, and S. C. Brooks, 1948; E. L. Chambers, 1949; Chambers and 

 Chambers, 1949) ; also for S. purpuratus. 



Replacement. — Of K ion by rubidium and cesium, but not by thorium and uranium 

 (R. F. Loeb, 1920). 



Chemical Character. — And physiological action of potassium ion (J. Loeb, 1920). 



Toxicity. — KCl less than NaCl (Loeb, 1900a; R. S. Lillie, 19 10, 1911a, b, 191 2; 

 Page, 1924, 1929 b; Chambers and Chambers, 1938; et al.). For toxicity on Arbacia 

 eggs. Page (1929b) arranges cations thus: Li > Na > Mg or Ca > K > Rb > Cs, 

 used as chlorides. Toxic effect can be counteracted by CaClg and MgClj and certain 

 anaesthetics (R. S. Lillie, 1911b, 191 2). 



Isotonic K CI has little effect on unfertilized eggs, and only in susceptible periods on 

 fertilized eggs; also for other K salts and for S. purpuratus (Chambers and Chambers, 



1938, 1949)- 



Pigment Granules. — In unfertilized egg are not affected by isotonic KCl; in fer- 

 tilized egg they break down after monaster stage (Churney and Moser, 1940). 

 Isotonic KCl prevents action of Ca on pigment granules which causes them to 

 break down in the surface precipitation reaction (Heilbrunn, 1928, p. 230). 



Hyaline Layer. — Absent in isotonic KCl (Chambers and Chambers, 1949). 



Sperm. — Immobilised in KCl at pH 6.0 (Chambers and Chambers, 1949). 



