OF EXPERIMENTAL WORK 203 



Liquid removed with pipette from perivitelline space by Chambers causing col- 

 lapse of membrane (Garrey, 1919). Fine suspension of carbon in sea water injected 

 in perivitelline space (Chambers, 1942). 



Electrical Properties .—Bears positive charge (McClendon, 1910b, 1912b, 1914a). 



Other Species (additional) 



Gray, 1927 b. E. esculentus, Psammechinus miliaris. 

 Hiramoto, 1954. Hemicentrotus ( Strongylocentrotus ) pulcherrimus. 

 Hobson, 1927. E. esculentus, Ps. miliaris. 

 Mitchison and Swann, 1953. Ps. miliaris, colloid. 



PERMEABILITY 



A. Unfertilized Egg. — 



/. Penetration of water; osmotic properties. Change in size in hypo- and hyper- 

 tonic sea water (Sollman, 1904b; R. S. Lillie, 1910-1918; Loeb, 1913a, p. 61; 

 Lucke, et al. including McCutcheon, Hartline, Larrabee, Ricca, Parpart, 1926- 

 1951 ; Northrop, 1927; Jacobs, 1933a, b, c; Stewart and Jacobs, 1936; E. B. Haivey, 

 1943. See Table 12; Shapiro, 1948 b, et al. Reviews by Luck^ and McCutcheon, 

 1932; Luck^, 1940; Wilbrandt, 1941 in Tabulae Biologicae, Vol. 19 (Pt. 2), pp. 371- 

 389 for tables. See Plate XIV. 



Equilibrium size given by (V„ — b)P„ = (V^^ — b)P,^, where V„ = volume in 

 sea water, P^ = osmotic pressure sea water, W^^. = volume in concentrated or 

 diluted sea water, P,^, = osmotic pressure in concentrated or diluted sea water, 

 b = osmotically inactive material (Lucke and McCutcheon, 1932; Lucke, 1940). 

 Complete recovery on return to sea water. Temperature has no effect on equilibrium 

 (Lucke, 1935). 



Osmotically inactive material b, 6-20 %, average 12 % (McCutcheon, Lucke, and 

 Hartline, 1931; Lucke, Larrabee, and Hartline, 1935). Increase on fertilization 

 (Shapiro, 1948 b). 



Rate of water penetration. Permeability to water is defined as: 



dV 



''J = kA(P-P,;;, 



where dV/dt = rate of change in volume, A = surface area, P = osmotic pressure 

 at time t, P^^. = osmotic pressure within egg or of solution with which cell is in 

 equilibrium, and k the permeability constant. For integrated equations and discus- 

 sion of derivation see Lucke and McCutcheon, 1932, Lucke, 1940. 



Endosmosis and exosmosis. For water entering eggs at 20 °C., k = 0.087 (x' per jj.^ 

 surface per atmosphere difference of pressure per minute ; for water leaving eggs, 

 k = 0.141 (x^. At 15 °C., k = 0.05 — 0.06 for endosmosis and 0.07-0.08 for exos- 

 mosis. Values are independent of osmotic pressure but depend on kind and propor- 

 tions of salt in medium, injury, narcotics, temperature, etc. (Lucke, Hartline, and 

 McCutcheon, 193 1). At 22 'C. by diffraction method of study, k = 0.106 for endos- 

 mosis and 0.127 for exosmosis (Lucke, Larrabee, and Hartline, 1935) ; also Stewart 

 and Jacobs, 1936. 



2. Penetration of heavy water same as water (Luck^ and E. N. Harvey, 1935)- 



3. Penetration of non-electrolytes. Permeability to a solute (S) may be defined as 



kA(Cs-|) 



dS , . /^ S 

 dt 



where dS/dt = rate of change of amount of solute; A = surface area; Cs = external 

 concentration; V = volume of the egg., k = number of moles that will penetrate 



