OF EXPERIMENTAL WORK I99 



Harvey, and Hollaender, 1937; HoUaender, 1938; Moser, 1939b; E. N. Har- 

 vey, 1942). 



8. X-rays (E. B. Harvey unpub. ; negative, Richards, 19 15). 



b. Chemical. 



<r^ I. Oxygen lack or diminished oxygen (Mathews, 1900; McClendon, 1909b, 

 1910b). 



,-^. Hypertonic sea water, by evaporation (S.J. Hunter, 1901, 1903; Greely, 

 1903; McClendon, 1909 b, 1910 b; Glaser, 1913; Just, 1928 c; E. B. Harvey, 

 1936, 1940c). 



3. Hypotonic sea water or distilled water (McClendon, 1909b, 1910b; 

 "i^^er, 1913; Just, 1928a, 1939a, p. 45, distilled water 15 seconds; 1939b, 



p. 233; Heilbrunn, 1928, p. 261; E. B. Harvey, 1940 c). 



4. Salts. 



NaCl (Morgan, 1898, 1899, 1900a, b; Loeb, 1900b, 1901, 1913a, p. 60, etc.; 

 Greeley, 1903; McClendon, 1909b, 1910b; Heilbrunn, 1915a, 1928, p. 261; 

 C. R. Moore, 191 7; Just, 1922 a I, 1939a, b, p. 224; E. B. Harvey, 1936, 1940c; 

 et al.). 



NaCl, NaBr, NaNOa, Nal, NaCNS (R. S. Lillie; 1910, 1911b). 

 Na2S04 (Just, 1929a). 



KCl (Morgan, 1899, 1900b; Loeb, 1900a, b, 1901, 1913a, p. 60, etc.; Just, 

 1922a I, 1939a, b, p. 224; E. B. Harvey, 1936). 

 KI, KCNS (R. S. Lillie, 1910, 1911b). 

 — J^CaClj (Loeb, 1900a, 1913a, p. 59, etc.; Hollingsworth, 1941). 



'^MgClg (Morgan, 1899, 1900 a, b; Loeb, 1899, 1900 a, b, 1901, 1913 a, p. 57, 

 etc.; Greeley, 1903; Hollingsworth, 1941 ; et al.). 

 BaClj (Just, 1929 a; Hollingsworth, 1941). 

 SrClg (Hollingsworth, 1941; see Heilbrunn, 1915a). 

 HgClg (F. R. Lillie, 1921b; Hoadley, 1923, 1930; Heilbrunn, i925d). 



5. Acids. 



HCl, HNO3, feeble; H2SO4, negative (Loeb, 1900a, 1901, 1913a, p. 57, 138). 

 CO2 (McClendon, 1909b, 1910b; McClendon and Mitchel, 191 2; Jacobs, 

 1922). 



Acetic acid (McClendon, 1909b, 1910b; D. Harding, 1951). 

 Lactic, phosphoric, butyric acids and injury substances (D. Harding, 1951). 

 ■--^Butyric acid, alone. Fertilization membrane only (Loeb, 1913a, p. 71, 1915a; 

 F. R. Lillie, 1914; Heilbrunn, 1915a; C. R. Moore, 19 16; Just, 1939b, p. 222). 

 2-cell (A. R. Moore, 191 5). Et al. 

 <^Butyric acid + hypertonic sea water, Loeb's double method (Loeb, 1913 a, 

 p. 71, 1916, p. 99: 50 cc. sea water +2 cc. N/io butyric acid for 2-4 min.; 

 sea water 10-15 min.; 50 cc. sea water +8 cc. 2^ m NaCl for 17^— 22^^ min.; 

 sea water; at 23 °C.) Heilbrunn (1915a, p. 170) advises only ^ min. in 50 cc. 

 sea water + 2.8 cc. N/io butyric, then hypertonic sea water. This method has 

 been used by Just (1939b, p. 222) and many others, but hypertonic sea water 

 alone is much simpler and gives good results. 



Many other fatty acids have been used by Loeb (1913a, pp. 67, 134, 185) for 

 Strongylocentrotus purpuratus, and would probably work for Arbacia. 



6. Alkalis and amines. 



NaOH, KOH, NH4OH (Loeb, 1900a, 1913a, p. 57; McClendon, 1909b, 

 1910b); membranes form in solutions more alkaline than pH 9.0 (Smith and 

 Clowes, 1924b). NH4OH (weak base) better than NaOH, KOH or tetraethyl- 

 ammonium hydroxide (strong bases) (Loeb, 1912 b, 1913a, p. 147). 

 Amines (butylamine, benzylamine, protamine (Loeb, 1913 a, p. 149). 



7. Fat solvents, esters and narcotics. 



Toluol (Heilbrunn, 1915a, 1928, p. 261; Heilbrunn and Young, 1930; 



