OF EXPERIMENTAL WORK 221 



Chemical composition of shell oi^ Arbacia lixula (Terentieva, 1932; tabulation by 

 Vinogradov, 1953, p. 252). 



CaCOg 90.08 % of ash residue 



MgCOs 7-72 



CaS04 2.20 



Chemical composition of plates of Echinus esculentus (Biitschli, 1908, p. 81 ; tabulated 

 by Vinogradov, 1953, p. 252; also in Grasse's Traiti de ^oologie, 1948, vol. 1 1, p. 8). 

 CaCOg (calcite) 86.40 89.64 % of ash residue 



MgCOg 8.53 8.84 



Phosphate 0.08 0.08 



CaS04 + 2H2O 1.70 1.40 



SiOj 0.04 0.04 



Organic material 0.03 



Chemical composition of other Echinoid skeletons and skeletal parts (Tabulation 

 by Vinegradov, 1953, p. 252, 255 etc.). 



Red pigment (echinochrome) in shell of Arbacia is present as a Ca salt or adsorbed 

 on CaCO., (Ball, see under Echinochrome) ; as a Ca salt in S. purpuratus (Tyler, 

 1939)- 



SODIUM 



Amount in Egg. — 1.301 mg. Na per 10' eggs (10* eggs = 0.124 S"^- dry weight), or 

 0.056 millimoles (Page, 1927b). 



Amount in Sea Water. — At Woods Hole. 8.80 gm. per liter at 20 ""C. (Page, 1927c, 

 1928). 



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

 Howard, 193 1). 



NaCl Isotonic. — With sea water at Woods Hole is 0.53 M (M. B. L. Chemical 

 Room) . 



Toxicity. — NaCl more toxic than KCl. Delays or prevents cleavage (Loeb, 1900 a, 

 R. S. Lillie, 1910, 1911a, b, 1912; Page, 1924, 1929b; Chambers and Chambers, 

 1938; et al.). Toxic effects counteracted by CaClg and MgClg (Mathews, 1905; R. S. 

 Lillie, 191 1 a, b, 191 2) ; also by some anaesthetics (R. S. Lillie, 19 12). 



Surface Precipitation Reaction. — Prevented by NaCl; prevents breakdown of pigment 

 granules by Ca (Heilbrunn, 1928, p. 229). 



Surface Potential of Egg. — (Dan, 1936). 



Cytolysis. — Caused by NaCl (E. N. Harvey, 1910c; Loeb and Wasteneys, 1910; 

 Loeb, 1913 a, p. 180; R. S. Lillie, 191 2; Heilbrunn, 1928, p. 251 ; Mazia, 1933; Dan, 

 1936; et al.). 



Jelly. — NaCl (0.54 M) dissolves jelly and causes agglutination of eggs; prevented 

 by CaCl,. (R. S. Lillie, 192 1). 



Colorless Amoebocytes of Body Fluid. Dissolved by NaCl (Mathews, 1900). 



Fertilized Egg. — When NaCl added to sea water, nuclear division without cell 

 division (Loeb, 1892, 1895b, 1900a, etc.). Also astrospheres (Morgan, 1899). 



Respiration. — Increase (Mitchell and McClendon, 191 1; McClendon and Mit- 

 chell, 1912; Heilbrunn, 1943, p. 455; but see Loeb and Wasteneys, 1910). 



Permeability. — Increase, as indicated by dissolving of pigment granules in the order 

 of: NaCl < NaBr < NaNOg < NaCNS < Nal ; also toxic and effective as parthe- 

 nogenetic agents in this order. Na salts more effective (and more toxic) than K salts. 

 Increased permeability can be antagonized by CaCl 2 and MgCl, and some anaes- 

 thetics (R. S. Lillie, 1910, 1911a, b. 191 2; McCutcheon and Lucke, 1928: also 

 Heilbrunn, 1943, p. 142). 



