OF EXPERIMENTAL WORK 



175 



and by Cornman (1941) for A. punctulata. See Hartmann, Schartau, and Wallenfels 

 (1940). 



Fertilization. — Inhibited by echinochrome from red amoebocytes; has no effect on 

 cleavage if eggs exposed after fertiHzation ; binds calcium ; causes agglutination of 

 sperm (Couillard, 1952). Allee et al. (1942) also found no effect on cleavage. 



For release. — Of echinochrome from chromatophores, see under Chromatophores. 



Other Species (additional) and General References 



Baldwin, 1952, p. 184 General. 



Fox, 1953. Biochromes. 



Fox and Scheer, 1941. Pacific coast forms. 



Goodwin, Lederer, and Musago, 1951. Spinochromes, nomenclature. 



Goodwin and Srisukh, 1950. E. esculentus, P. lividus, 5 pigments. 



Goodwin and Srisukh, 1951. Echinocardium cordatum, echinochrome almost absent. 



Krahl, 1950. Review. 



Lederer, 1940. Review. 



ECTOPLASMIC LAYER 



See Hyaline Layer 



ELECTRICAL PROPERTIES AND EFFECTS 



L Electrical properties of eggs. 



A. Membrane capacity and internal resistance (From Cole's 1941 Table in 

 Tabulae Biologicae, vol. 19, Part II, p. 25). 



Internal Resistance 

 ohm/cm^ 



90 (Cole, 1928) 



186 (Cole and Cole, 1936; 

 186 Cole, 1937, 1938) 



147 (Cole and Spencer, 1938) 

 180 



180 (Cole and Curtis, 1938) 

 210 



125 (Cole and Curtis, 1938) 

 125 



360-775 (Cole and Curtis, 1938) 



B. Surface charge; Zeta potential (Dan, 1933; see also 193 1). 

 Unfertilized eggs with jelly — 34.1 ± 0.47 millivolts 

 Unfertilized eggs without jelly — 30.3 ± 0.47 millivolts 

 Fertilized eggs without jelly — 28.7 ± 0.42 millivolts 

 Unfertilized eggs without jelly, in dead sperm suspension —26.7 ± 0.56 



millivolts 

 Cleaving eggs without jelly — 27.2 millivolts 



